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34 | Topics covered: Exceptions to Lewis structure rules; Ionic bonds
Instructor: Catherine Drennan, Elizabeth Vogel Taylor
Lecture Notes (PDF - 1.1MB)
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PROFESSOR: OK, let's get started here. Go ahead and take 10 more seconds on the clicker question, which probably looks all too familiar at this point, if you went to recitation yesterday. All right, and let's see how we do here.
OK. So, let's talk about this for one second. So what we're asking here, if we can settle down and listen up, is which equations can be used if we're talking about converting wavelength to energy for an electron. Remember, the key word here is electron. This might look familiar to the first part of problem one on the exam, and problem one on the exam is what tended to be the huge problem on the exam. I think over 2/3 of you decided on the exam to use this first equation, e equals h c over wavelength.
So I just want to reiterate one more time, why can we not use this equation if we're talking about an electron? C. OK, good, good, I'm hearing it. So the answer is c. What you need to do is you need to ask yourself if you're trying to convert from wavelength to energy for an electron, and you are tempted, because we are all tempted to use this equation, and if you were tempted, say, does an electron travel at the speed of light? And if the answer is no, an electron does not travel at the speed of light, light travels at the speed of light, then you want to stay away from using this equation. And I know how tempting it is to do that, but we have other equations we can use -- the DeBroglie wavelength, and this is just a combination of energy equals 1/2 m v squared, and the definition of momentum, so we can combine those things to get it.
You might be wondering why I'm telling you this now, you've already -- if you've lost points on that, lost the points on it, and what I'm saying to you is if there are parts of exam 1 that you did not do well on, you will have a chance to show us again that you now understand that material on the final. One quarter of the final is going to be exam 1 material, and what that means is when we look at your grade at the end of the semester, and we take a look at what you got on exam 1, and you're right at that borderline, and we say well, what happened, did they understand more at the end of the semester, did the concepts kind of solidify over the semester? And if they did and if you showed us that they did, then you're going to get bumped up into that next grade category.
So keep that in mind as you're reviewing the exam, sometimes if things don't go as well as you want them to, the temptation is just to put that exam away forever and ever. But the reality is that new material builds on that material, and specifically exam 1 a, question 1 a that deals with converting wavelength to energy for an electron. I really want you guys know this and to understand it, so I can guarantee you that you will see this on the final. Specifically, question 1, part a. You will see something very, very similar to this on the final. If you are thinking about 1 thing to go back and study on exam 1, 1 a is a really good choice for that. This is important to me, so you're going to see it on the final.
So if you have friends that aren't here, you might want to mention it to them, or maybe not, maybe this is your reward for coming to class, which is fine with me as well.
All right. So I want to talk a little bit about exam 1. I know most you picked up your examine in recitation. If you didn't, any extra exams can be picked up in the Chemistry Education office, that's room 2204.
So, the class average for the exam was a 68%, which is actually a strong, solid average for an exam 1 grade in the fall semester of 511-1. What we typically see is something right in this range, either ranging from the 50's for an exam 1 average to occasionally getting into the 70's, but most commonly what we've seen for exam 1 averages is 60, 61 -- those low 60's. So in many ways, seeing this 68 here, this is a great sign that we are off to a good start for this semester. And I do want to address, because I know many of you, this is only your second exam at MIT, and perhaps you've never gotten an exam back that didn't start with a 90 or start with an 80 in terms of the grades. So one thing you need to keep in mind is don't just look at the number grade. The reason that we give you these letters grade categories is that you can understand what it actually means, what your exam score actually says in terms of how we perceive you as understanding the material.
So, for example, and this is the same categories that were shared in recitation, so I apologize for repeating, but I know sometimes when you get an exam back, no more information comes into your head except obsessing over the exam, so I'm just going to say it one more time, and that is between 88 and 100, so that's 20% of you got an A. This is just absolutely fantastic, you really nailed this very hard material and these hard questions on the exam where you had to both use equations and solve problems, but also understand the concept in order to get yourself started on solving the problem.
The same with the B, the B range was between 69 and 87 -- anywhere in between those ranges, you've got a B, some sort of B on the exam. So again, if you're in the A or the B category here, this is really something to be proud of, you really earned these grades. You know these exams, our 511-1 exams, we're not giving you points here, there are no give me, easy points, you earned every single one of these points. So, A and B here, these are refrigerator-worthy grades, hang those up in your dorm. This is something to feel good about.
All right. So, for those of you that got between a 51 and a 68, this is somewhere in the C range. For some people, they feel comfortable being in the C range, other people really do not like being in this range. We understand that, there is plenty of room up there with the A's and the B's. You are welcome to come up to these higher ranges starting with the next exam. And what I want to tell you if you are in the C range, and this is not a place that you want to be in, anyone that's got below the class average, so below a 68 -- or a 68 or below, is eligible for free tutoring, and I put the website on the front page of your notes. This means you get a one-on-one tutor paid for by the Chemistry Department to help you if it's concepts you're not quite up on, if it's exam strategy that you need to work on more. Whatever it is that you need to work on, we want to help you get there.
So, if you have a grade that you're not happy with, that you're feeling upset or discouraged about, please, I'm happy to talk to all of you about your grades individually. You can come talk to me, bring your exam, and we'll go over what the strategy should be in terms of you succeeding on the next exam. You can do the same thing with all of your TAs are more than happy to meet with each and every one of you. And then in addition to that, we can set you up with a tutor if you are in the C range or below, in terms of this first exam.
All right. So 44 to 50, this is going to be in the D range. And then anything below a 44 is going to be failing on this exam. And also keep in mind, for those of you that are freshman, you need at least a C to pass the class. So, if you did get a D or an F on the first exam, you are going to need to really evaluate why that happened and make some changes, and we're absolutely here to help you do that. So the real key is identifying where the problem is -- is it with understanding the concepts, are you in a study group that's dragging you along but you're not understanding? Do you kind of panic when you get in the exam? There are all sorts of scenarios we can talk about and we want to talk about them with you.
Seriously, even if we had a huge range in this exam from 17 to 100, if you're sitting there and you're the 17, and actually there's more than 1 so don't feel alone, if you're a 17 or you're a 20, it's not time to give up, it's not time to drop the class and say I'm no good at chemistry, I can't do this. You still can, this is your first couple of exams, certainly your first in this class, potentially one of your first at MIT, so there's tons of room to improve from here on out. This is only 100 points out of 750. So, the same thing goes if you did really well, you still have 650 other points that you need to deal with. So, make sure you don't just rest on your high score from this first exam.
So, OK, so that's pretty much what I wanted to say about the exam, and in terms of there's tons of resources if things didn't work out quite as you wanted. If you feel upset in any way, please come and talk to me. We want you to love chemistry and feel good about your ability to do it. Nobody get into MIT by mistake, so you all deserve to be sitting here, and you all can pass this class and do well in it, so we can help you get there no matter what. You all absolutely can do this.
And then one more time, to reiterate, in case anyone missed it, 1 a, make sure you understand that, I feel like that's important. And actually all of 1 -- I really feel like the photoelectric effect is important for understanding all of these energy concepts. So, as you go on in this class, make sure you don't go on before you go back and make sure you understand that problem.
All right, so let's move on to material for exam 2 now, and we're already three lectures into exam 2 material. And I do want to say that in terms of 511-1, what tends to happen is the exam scores go up and up and up, in terms of as we go from exam 1, to exam 2, to exam 3. One of these reasons is we are building on material, the other reason is you'll be shocked at how much better you are at taking an exam just a few weeks from now. So this will be on, starting with the Lewis structures, so go back in your notes -- if this doesn't sound familiar, if you spent too much time -- or not too much time, spent a lot of time studying exam 1 and didn't move on here.
Today we're going to talk about the breakdown of the octet rule. Cases where we don't have eight electrons around our Lewis structures, then we'll move on to talking about ionic bonds. We had already talked about covalent bonds, and then we talked about Lewis structures, which describe the electron configuration in covalent bonds. So now let's think about the other extreme of ionic bonds, and then we'll talk about polar covalent bonds to end, if we get there or will start with that in class on Monday.
Also, public service announcement for all of you, voter registration in Massachusetts, which is where we are, is on Monday, the deadline if you want to register to vote. There's some websites up there that can guide you through registering and also can guide you through, if you need an absentee ballot for your home state. And I actually saw, and I saw a 5.111 student manning, there's some booths around MIT that will register you or get you an absentee ballot. So, the deadline's coming soon, so patriotic duty, I need to remind you of that as your chemistry teacher -- chemistry issues are important in politics as well. So make sure you get registered to vote.
I just remembered one more announcement, too, that I did want to mention, some of you may have friends in 511-2 and have heard their class average for exam 1. And I want to tell you, this happens every year, their average was 15 points higher than our average. Last year, their average was 15 points higher than our average. This is for exam 1. This is what tends to happen to 511-2 grades as the exam goes on. This is what happens to 511-1. You guys are in a good spot. Also, I want to point out that what's not important is just that number grade, but also the letter that goes with it.
So, for example, if you got a 69 in this class on this exam, that's a B minus. If you got a 69 on your exam in 511-2, that's a D, you didn't pass the exam. So keep that in mind when your friend might have gotten a higher number grade than you and you know you understand the similar material just as well. Similarly, an 80 in this class on the exam was a B plus, a very high B. An 80 in that class is going to be a C. So, just don't worry so much about exactly where that average lies, you really want to think about what the letter grade means. OK, I've said enough. I just -- I hate to see people discouraged, and I know that a few people have been feeling discouraged, so that's my long-winded explanation of exam 1 grades.
All right. So, let's move on with life though, so talking about the breakdown of the octet rule. The first example where we're going to see a breakdown is any time we have an odd number of valence electrons. This is probably the easiest to explain and to think about, because if we have an odd number that means that we can't have our octet rule, because our octet rule works by pairing electrons. And if we have an odd number, we automatically have an odd electron out.
So, if we look at an example, the methyl radical, we can first think about how we draw the Lewis structure -- we draw the skeletal structure here. And then what we're going to do is add up our valence electrons -- we have 3 times 1 for the hydrogen atoms, carbon has 4 valence electrons, so we have a total of 7. If we want to fill all of our valence shells in each of these atoms, we're going to need a total of 14 electrons. So, what we see we're left with is that we have 7 bonding electrons. So we can fill in 6 of those straightforward here, because we know that we need to make 3 different bonds. And now we're left over with 1 electron, we can't make a bond.
So, what we'll do is carbon does not have an octet yet. We can't get it one, but we can do the best we can and help it out with adding that extra electron onto the carbon atom, so that at least we're getting as close as possible to filling our octets.
This is what we call a radical species or a free radical. Free radical or radical species is essentially any type of a molecule that has this unpaired electron on one of the atoms. This might look really strange, we're used to seeing octets. But you'll realize, if you calculate the formal charge on this molecule, that it's not the worst situation ever for carbon. At least it's formal charge is zero, even if it doesn't have -- it would rather have an extra bond and have a full octet. But it's not the worst scenario that we can imagine. But still, radicals tend to be incredibly reactive because they do want to fill that octet.
So, what happens when you have a radical is it tends to react with the first thing that it runs into, especially highly reactive radicals that are not stabilized in some other way, which you'll tend to talk about it organic chemistry -- how you can stabilize radicals.
So the term free radical should sound familiar to you, whether you've heard it in chemistry before, or you haven't heard it in chemistry, but maybe have heard it, I don't know, commercials for facial products or other things. People like to talk about free radicals, and they're sort of the hero that gets rid of free radicals, which are antioxidants. So you hear in a lot of different creams or products or vitamins that they have antioxidants in them, which get rid of free radicals. The reason you would want to get rid of free radicals is that free radicals can damage DNA, so they're incredibly reactive. It makes sense that if they hit a strand of DNA, they're going to react with the DNA, you end up breaking the strands of DNA and causing DNA damage.
So, this is actually what happens in aging because we have a lot of free radicals in our body. We can introduce them artificially, for example, cigarette smoke has a lot of really dangerous free radicals that get into the cells in your lungs, which damage your lung DNA, which can cause lung cancer. But also, all of us are living and breathing, which means we're having metabolism go on in our body, which means that as we use oxygen and as we metabolize our food, we are actually producing free radicals as well. So it's kind of a paradox because we need them because they are a natural by-product of these important processes, but then they can go on and damage cells, which is what kind of is causing aging and can lead to cancer.
We have enzymes in our body that repair damage that is done by free radicals, that will put the strands of DNA back together. And we also have antioxidants in our body. So, you might know that, for example, very brightly colored fruit is full of antioxidants, they're full of chemicals that will neutralize free radicals. Lots of vitamins are also antioxidants, so we have vitamin A on the top there and vitamin E.
So, the most common thing we think of when we think of free radicals is very reactive, bad for your body, causes DNA damage. But the reality is that free radicals are also essential for life. So this is kind of interesting to think about. And, for example, certain enzymes or proteins actually use free radicals in order to carry out the reactions that they carry out in your body. So, for example, this is a picture or a snapshot of a protein, this is a crystal structure of ribonucleotide reductase is what it's called. It's an enzyme that catalyzes the reaction of an essential step in both DNA synthesis and also DNA repair, and it requires having radicals within its active site in order to carry out the chemistry.
So, this is kind of a neat paradox, because radicals damage DNA, but in order to repair your DNA, you need certain enzymes, and those enzymes require different types of free radicals. So, free radicals are definitely very interesting, and once we get -- or hopefully you will get into organic chemistry at some point and get to really think about what they do in terms of a radical mechanism.
We can think about radicals that are also more stable, so let's do another example with the molecule nitric acid. So we can again, draw the skeleton here, and just by looking at it we might not know it's a radical, but as we start to count valence electrons, we should be able to figure it out very quickly, because what we have is 11 valence electrons. We need 16 electrons to have full octets. So, we're left with 5 bonding electrons. We put a double bond in between our nitrogen and our oxygen, so what we're left over with is this single bonding electron, and we'll put that on the nitrogen here. And I'll explain why we put it on the nitrogen and not the oxygen in just a minute.
But what we find is then once we fill in the rest of the valence electrons in terms of lone pairs, this is the structure that we get. And if you add up all of the formal charges on the nitrogen and on the oxygen, what you'll see is they're both 0. So if you happen to try drawing this structure and you put the lone pair on oxygen and then you figured out the formal charge and saw that you had a split charge, a plus 1 and a minus 1, the first thing you might want to try is putting it on the other atom, and once you did that you'd see that you had a better structure with no formal charge.
I have to mention what nitric oxide does, because it's a very interesting molecule. Don't get it confused with nitrous oxide, which is happy gas, that's n o 2. This is nitric oxide, and it's actually much more interesting than nitrous oxide. It's a signaling molecule in your body, it's one of the very few signaling molecules that is a gas, and obviously, it's also a radical. What happens with n o is that it's produced in the endothelium of your blood vessels, so the inner lining of your blood vessels, and it signals for smooth muscle that line your blood vessels to relax, which causes vasodilation , and by vasodilation, I just mean a widening of the blood vessels. So, n o signals for your blood vessels to get wider and allow more blood to flow through. And if you think about what consequences this could have, in terms of places where they have high altitude, so they have lower oxygen levels, do you think that they produce more or less and n o their body? More? Yeah, it turns out they do produce more. The reason they produce more is that they want to have more blood flowing through their veins so that they can get more oxygenated blood into different parts of their body.
N o is also a target in the pharmaceutical industry. A very famous one that became famous I guess over 10 years ago now, and this is from a drug that actually targets one of n o's receptors, and this drug has the net effect of vasodilation or widening of blood vessels in a certain area in the body. So this is viagra, some of you may be familiar, I think everyone's heard of viagra. Now you know how viagra works. Viagra breaks down, or it inhibits the breakdown of n o's binding partner in just certain areas, not everywhere in your body. So, in those areas, what happens is you get more n o signaling, you get more vasodilation, you get increased blood flow. So that's a little bit of pharmacology for you here today.
All right, so let's talk about one more example in terms of the breakdown of the octet rule with radicals. Let's think about molecular oxygen. So let's go ahead and quickly draw this Lewis structure. We have o 2. The second thing we need to do is figure out valence electrons. 6 plus 6, so we would expect to see 12. For a complete octet we would need 8 electrons each, so 16. So in terms of bonding electrons, what we have is 4 bonding electrons. So, we can go ahead and fill those in as a double bond between the two oxygens.
So, what we end up having left, and this would be step six then because five was just filling in that, is 12 minus 4, so we have 8 lone pair electrons left. So we can just fill it in to our oxygens like this.
All right, so using everything we've learned about Lewis structures, we here have the structure of molecular oxygen. And I just want to point out for anyone that gets confused, when we talk about oxygen as an atom, that's o, but molecular oxygen is actually o 2, the same for molecular hydrogen, for example.
All right, so let's look at what the actual Lewis structure is for molecular oxygen, and it turns out that actually we don't have a double bond, we have a single bond, and we have two radicals. And any time we have two radicals, we talk about what's called a biradical. And while using this exception to the Lewis structure rule, to the octet rule for odd numbers of valence electrons can clue us into the fact that we have a radical, there's really no way for us to use Lewis structures to predict when we have a biradical, right, because we would just predict that we would get this Lewis structure here.
So, when I first introduced Lewis structures, I said these are great, they're really easy to use and they work about 90% of the time. This falls into that 10% that Lewis structures don't work for us. It turns out, in order to understand that this is the electron configuration for o 2, we need to use something called molecular orbital theory, and just wait till next Wednesday and we will tell you what that is, and we will, in fact, use it for oxygen. But until that point, I'll just tell you that molecular orbital theory takes into account quantum mechanics, which Lewis theory does not. So that's why, in fact, there are those 10% of cases that Lewis structures don't work for.
All right, the second case of exceptions to the octet rule are when we have octet deficient molecules. So basically, this means we're going to have a molecule that's stable, even though it doesn't have a complete octet. And these tend to happen in group 13 molecules, and actually happen almost exclusively in group 13 molecules, specifically with boron and aluminum. So, any time you see a Lewis structure with boron or aluminum, you want to just remember that I should look out to make sure that these might have an incomplete octet, so look out for that when you see those atoms.
So, let's look at b f 3 as our example here. And what we see for b f 3 is the number of valence electrons that we have are 24, because the valence number of electrons for boron is 3, and then 3 times 7 for each fluorine. For total filled octets we need 32, so that means we need 8 bonding electrons. So, let's assign two to each bond here, and then we're going to have two extra bonding electrons, so let's just arbitrarily pick a fluorine to give a double bond to. And then we can fill in the lone pair electrons, we have 16 left over. So thinking about what the formal charge is, if we want to figure out the formal charge for the boron here, what we're talking about is the valence number for boron, which is 3, minus because there are no lone pairs, minus 1/2 of 8 because there are eight shared electrons. We get a formal charge of minus 1.
What is our formal charge since we learned this on Monday for thinking about the double bonded fluorine in boron? So, look at your notes and look at the fluorine that has a double bond with it, and I want you to go ahead and tell me what that formal charge should be.
All right, let's take 10 more seconds on that. OK, so 49%. So, let's go look back at the notes, we'll talk about why about 50% of you are right, and 50% need to review, which I totally understand you haven't had time to do yet, your formal charge rules from Monday's class, there were other things going on. But let's talk about how we figure out formal charge. Formal charge is just the number of valence electrons you have. So fluorine has 7. You should be able to look at a periodic table and see that fluorine has seven. What we subtract from that is the number of lone pair electrons, and there are four lone pair electrons on this double bonded fluorine, so it's minus 4. Then we subtract 1/2 of the shared electrons. Well we have a double bond with boron here, so we have a total of 4 shared electrons. And when we do the subtraction here, what we end up with is a formal charge plus 1 on the double bonded fluorine.
Without even doing a calculation, what do you think that the formal charge should be on you single bonded fluorines? Good. OK, it should be and it is 0. The reason it's zero in terms of calculating it is 7 minus 6 lone pair electrons minus 1/2 half of 2 shared electrons is 0. The reason that you all told me, I think, and I hope, is that you know that the formal charge on individual atoms has to equal the total charge on the molecule. So if we already have a minus 1 and a plus 1, and we know we have no charge in the molecule, and we only have one type of atom left to talk about, that formal charge had better be 0.
OK. So this looks pretty good in terms of a Lewis structure, we figured out our formal charges. These also look pretty good, too, we don't have too much charge separation. But what actually it turns out is that if you experimentally look at what type of bonds you have, it turns out that all three of the b f bonds are equal in length, and they all have a length that would correspond to a single bond. So, experimentally, we know we have to throw out this Lewis structure here, we have some more information, let's think about how this could happen.
So this could happen, for example, is if we take this two of the electrons that are in the b f double bond and we put it right on to the fluorine here, so now we have all single bonds. And let's think about what the formal charge situation would be in this case here. What happens here is now we would have a formal charge of on the boron, we'd have a formal charge of on all of the fluorine molecules as well. So, it turns out that actually looking at formal charge, even though the first case didn't look too bad, this case actually looks a lot better. We have absolutely no formal charge separation whatsoever. It turns out again, boron and aluminum, those are the two that you want to look out for. They can be perfectly happy without a full octet, they're perfectly happy with 6 instead of 8 in terms of electrons in their valence shell. So that is our exception the number two.
We have one more exception and this is a valence shell expansion, and this can be the hardest to look out for, students tend to forget to look for this one, but it's very important as well, because there are a lot of structures that are affected for this . And this is only applicable if we're talking about a central atom that has an n value or a principle quantum number that's equal to or greater than three. What happens when we have n that's equal to or greater to three, is that now, in addition to s orbitals and p orbitals, what else do we have available to us? D orbitals, great. So what we see is we have some empty d orbitals, which means that we can have more than eight electrons that fit around that central atom.
If you're looking to see if this is going to happen, do you think this would happen with a large or small central atom? So think of it in terms of just fitting. We've got to fit more than 8 electrons around here. Yeah, so it's going to be, we need to have a large central atom in order for this to take place. Literally, we just need to fit everything around is probably the easiest way to think about it. And what happens is it also tends to have small atoms that it's bonded to. Again, just think of it in terms of all fitting in there.
So, let's take an example p c l 5. The first example is the more straightforward example, because let's start to draw the Lewis structure, and what we see is that phosphorous has five chlorines around it. So we already know if we want to form five bonds we've broken our octet rule. But let's go through and figure this out and see how that happens.
What we know is we need 40 valence electrons, we have those -- 5 from the phosphorous, and we have 7 from each of the chlorine atoms. If we were to fill out all of those octets, that would be 48 electrons. So what we end up with when we do our Lewis structure calculation is that we only have 8 bonding electrons available to us. So we can fill those in between the phosphorous and the chlorine, those 8 bonding electrons.
So, this is obviously a problem. To make 5 p c l bonds we need 10 shared electrons, and we know that that's the situation because it's called p c l 5 and not p c l 4, so we can go right ahead and add in that extra electron pair. So we've used up 10 for bonding, so that means what we have left is 30 lone pair electrons, and I would not recommend filling all of these in your notes right now, you can go back and do that, but just know the rest end up filling up the octets for all of the chlorines.
So, in this first case where you actually need to make more than for bonds, you will immediately know you need to use this exception to the Lewis structure octet rule, but sometimes it won't be as obvious. So, let's look at c r o 4, the 2 minus version here, so a chromate ion, and if we draw the skeletal structure, we have four things that the chromate needs to bond to.
So, let's do the Lewis structure again. When we figure out the valence electrons, we have total, we have 6 from the chromium, we have 6 from each of the different oxygens, and where did this 2 come from? Yup, the negative charge. So, remember, we have 2 extra electrons hanging out in our molecule, so we need to include those. We have a total of 32. 40 are needed to fill up octets. So again, we have 8 bonding electrons available, so we can go ahead and fill these in between each of the bonds. What happens is that we then have 24 lone pair electrons left, and we can fill those in like this. And the problem comes now when we figure out the formal charge.
So, when we do that what we find is that the chromium has a formal charge of plus 1, and that each of the oxygens has a total charge of minus 1. So we actually have a bit of charge separation here. Without even doing a calculation, what is the total charge of these that are added up? OK, it's minus 2, that's right. We know that the total charge of each of the formal charges has to add up to minus 2, because that's the charge in our molecule. We can also just calculate it -- the chromate gives us a plus 2, then we have 4 times minus 1 for each of the oxygens, so we have a minus 2.
So, we have some charge separation here, and in some cases, if we're not at n equals 3 or higher, there's really nothing we can do about it, this would be the best structure we can do. But since we have these d orbitals available, we can use them, and it turns out that experimentally this is what's found, that the length and the strength are not single bonds, but they're actually something between a single bond and a double bond.
So how do we get a 1 and 1/2 bond, for example, what's the term that let's us do that? Resonance. That's right. So that's exactly what's happening here. So, if we went ahead and drew this structure here where we have now two double bonds and two single bonds, that would be in resonance with another structure where we have two double bonds instead to these two oxygens, and now, single bonds to these two oxygens. We can actually also have several other resonance structures as well. Remember, the definition of a resonance structure is where all the atoms stay the same, but what we can do is move around the electrons -- we're moving around those extra two electrons that can be in double bonds.
So, why don't you tell me how many other resonance structures you would expect to see for this chromate ion? All right, let's take 10 more seconds on this.
All right. This is good. I know this is a real split response, but the right answer is the one that is indicated in the graph here that it's four. This takes a little bit of time to get used to thinking about all the different Lewis structures you can have. So, you guys should all go back home if you can't see it immediately right now and try drawing out those four other Lewis structures, for chromate, there are four others. You'll probably get a chance to literally do this example in recitation where you draw out all four, but it's even better to make sure you understand it before you get to that point. So, we can go back to the class notes.
So it turns out there's four other Lewis structures, so basically just think about all the other different combinations where you can have single and double bonds, and when you draw those out, you end up with four. So, for every single one of these Lewis structures, we could figure out what the formal charges are, and what we would find is that it's on the chromium, it's for the double bonded oxygens, and it's going to be negative 1 for the single bonded oxygens.
So, what you can see is that in this situation, we end up having less formal charge separation, and that's what we're looking for, that's the more stable structure. So any time you can have an expanded octet -- an expanded valence shell, where you have n is equal to or greater than 3, and by expanding and adding more electrons into that valence shell, you lower the charge separation, you want to do that.
I also want to point out, I basically said there's 6 different ways we can draw this in terms of drawing all the resonance structures. You might be wondering if you have to figure out the formal charge for each structure individually, and the answer is no, you can pick any single structure and the formal charges will work out the same. So, for example, if you pick this structure and your friend picks this structure, you'll both get the right answer that there's just the negative 1 on the oxygens and no other formal charges in the molecule.
All right. So those are the end of our exceptions to the octet rule for Lewis structures, that's everything we're going to say about Lewis structures. And remember, that when we talk about Lewis structures, what they tell us is the electron configuration in covalent bonds, so that valence shell electron configuration. So we talked a lot about covalent bonds before we got into Lewis structures, and then how to represent covalent bonds by Lewis structures.
So now I'll say a little bit about ionic bonds, which are the other extreme, and when you have an ionic bond, what you have now is a complete transfer of either one or many electrons between two atoms. So the key word for covalent bond was electron sharing, the key word for ionic bonds is electron transfer. And the bonding between the two atoms ends up resulting from an attraction that we're very familiar with, which is the Coulomb or the electrostatic attraction between the negatively charged and the positively charged ions.
So let's take an example. The easiest one to think about is where we have a negative 1 and a positive 1 ion. So this is salt, n a c l -- actually lots of things are call salt, but this is what we think of a table salt. So, let's think about what we have to do if we want the form sodium chloride from the neutral sodium and chlorine atoms. So, the first thing that we're going to need to do is we need to convert sodium into sodium plus.
What does this process look like to you? Is this one of those periodic trends, perhaps? Can anyone name what we're looking at here? Exactly, ionization energy. So, if we're going to talk about the energy difference here, what we're going to be talking about is the ionization energy, or the energy it takes to rip off an electron from sodium in order to form the sodium plus ion. So, we can just put right here, that's 494 kilojoules per mole.
The next thing that we want to look at is chlorine, so in terms of chlorine we need to go to chlorine minus, so we actually need to add an electron. This is actually the reverse of one of the periodic trends we talked about. Which trend is that this is the reverse of? Electron affinity, right. Because if we go backwards we're saying how badly does chlorine want to grab an electron? Chlorine wants to do this very badly, and it turns out the electron affinity for chlorine is huge, it's 349 kilojoules per mole, but remember, we're going in reverse, so we need to talk about it as negative 349 kilojoules per mole.
So if we talk about the sum of what's happening here, what we need to do is think about going from the neutrals to the ions, so we can just add those two energies together, and what we end up with is plus 145 kilojoules per mole, in order to go from neutral sodium in chlorine to the ions.
So, the problem here is that we have to actually put energy into our system, so this doesn't seem favorable, right. What's favorable is when we actually get energy out and our energy gets lower, but what we're saying here is that we actually need to put in energy. So another way to say this is this process actually requires energy. It does not emit energy, it does not give off excess energy, it requires energy.
So, we need to think about how can we solve this problem in terms of thinking about ionic bonds, and the answer is Coulomb attraction. So there's one more force that we need to talk about, and that is when we talk about the attraction between the negatively and the positively charged ions, such that we form sodium chloride. So this process here has a delta energy, a change in energy of negative 589 kilojoules per mole. So that's huge, we're giving off a lot of energy by this attraction. So if we add up the net energy for all of this process, all we need to do is add negative 589 to plus 145. So what we end up getting is the net energy change is going to be negative 444 kilojoules per mole, so you can see that, in fact, it is very favorable for neutral sodium and neutral chloride to form sodium chloride in an ionic bond. And the net increase then, is a decrease in energy.
So, I just gave you the number in terms of what that Coulomb potential would be in attraction, but we can I easily calculate it as well using this equation here where the energy is equal to the charge on each of the ions, and this is just multiplied by the value of charge for an electron divided by 4 pi epsilon nought times r, are r is just the distance in terms of the bond length we could talk about.
So, let's calculate and make sure that I didn't tell you a false number here. Let's say we do the calculation with the bond length that we've looked up, which is 2 . 3 6 angstroms for the bond length between sodium and chloride. So we should be able to figure out the Coulombic attraction for this.
So, if we talk about the energy of attraction, we need to multiply plus 1, that's the charge on the sodium, times minus 1, the charge on the chlorine, times the charge in an electron, 1 . 6 2 times 10 the negative 19 Coulombs, and that's all divided by 4 pi, and then I've written out epsilon nought in your notes, so I won't write it on the board. And then r, so r is going to be 2 . 3 6 and times -- what is angstrom, everyone? Yup, 10 to the negative 10. So 10 to the negative 10 meters. So, if we do this calculation here, what we end up with is negative 9.774 times 10 to the negative 19 joules.
So that's what we have in terms of our energy. That does not look the same as what we saw -- yup, do you have a question?
PROFESSOR: OK. Luckily, although, I did not write it in my own notes, I did it when I put in my calculator, thank you. So you need to square this value here and then you should get this value right here, negative 9.77.
All right, so what we need to do though is convert from joules into kilojoules per mole, because that's what we were using. So if we multiply that number there by kilojoules per mole -- or excuse me, first kilojoules per joule, so we have 1,000 joules in every kilojoule. And then we multiply that by Avagadro's number, 6.022 times 10 to the 23 per mole. What we end up with is negative 589 kilojoules per mole. So this is that same Coulombic attraction that we saw in the first place.
So, notice that you will naturally get out a negative charge here, remember negative means an attractive force in this case, because you have the plus and the minus 1 in here. So we should be able to easily do that calculation, and what we end up getting matches up with what I just told you, luckily, and thank you for catching the square, that's an important part in getting the right answer. So, experimentally then, what we find is that the change in energy for this reaction is negative 444 kilojoules per mole.
If we look experimentally what we see, it's actually a little bit different, it's negative 411 kilojoules per mole. So, in terms of this class, this is the method that we're going to use, and we're going to say this gets us close enough such that we can make comparisons and have a meaningful conversations about different types of ionic bonds and the attraction between them.
But let's think about where this discrepancy comes from, and before I do that I want to point out, one term we use a lot is change in energy for a reaction where, for example, you break a bond. Remember that the negative of the change in energy is what's called delta e sub d. We first saw this when we first introduced the idea of covalent bonds. Do you remember what this term here means, delta e sub d? A little bit and some no's, which this was pre-exam, I understand, you still need to review those notes, it's dissociation energy. So you get a negative energy out by breaking the bond. The dissociation energy means how much energy that bond is worth in terms of strength, so it's the opposite of the energy you get out of breaking the bond -- or excuse me, the energy that you get out of forming the bond. It's the amount of energy you need to put in to break the bond is dissociation energy. It takes this much energy to dissociate your bond, excuse me.
All right. So, let's take a look here at our predictions, so I just put them both ways so we don't get confused. The dissociation energy is 444. The change in energy for forming the bond is negative 444. We made the following approximations, which explain why, in fact, we got a different experimental energy, if we look at that.
The first thing is that we ignored any repulsive interactions. If you think about salt, it's not just two single atoms that you are talking about. It's actually in a whole network or whole lattice of other molecules, so you actually have some other chlorines around that are going to be having repulsive interactions with our chlorine that we're talking about. We're going to ignore those, make the approximation that those don't matter, at this point, in these calculations. And the result for that is that we end up with a larger dissociation energy than the experimental value. That's because the bond is going to be a little bit more broken than it was in our calculation, because we do have these repulsive interactions.
The other thing that we did is that we treated both sodium and the chlorine as point charges. And this is what actually allowed us to make this calculation and calculate the Coulomb potential so easily, we just treated them as if they're point charges. We're ignoring quantum mechanics in this -- this is sort of the class where we ignore quantum mechanics, we ignored it for Lewis structures, we're ignoring it here. We will be back to paying a lot of attention to quantum mechanics in lecture 14 when we talk about MO theory, but for now, these are approximations, these are models where we don't take it into consideration. And I think you'll agree that we come reasonably close such that we'll be able to make comparisons between different kinds of ionic bonds.
All right. So, the last thing I want to introduce today is talking about polar covalent bonds. We've now covered the two extremes. One extreme is complete total electron sharing -- if we have a perfectly covalent bond, we have perfect sharing. The other is electron transfer in terms of ionic bonds. So when we talk about a polar covalent bond, what we're now talking about is an unequal sharing of electrons between two atoms.
So, this is essentially something we've seen before, we just never formally talked about what we would call it. This is any time you have a bond forming between two non-metals that have different electronegativities, so, for example, hydrogen choride, h c l. The electronegativity for hydrogen is 2.2, for chlorine it's 3.2. And in general, what we say is we consider a difference in terms of a first approximation if the difference in electronegativity is more than 0. 5, so this is on the Pauling electronegativity scale. So what we end up having is we sort of have a kind of, and what we call it is a partial negative charge on the chlorine, and a partial positive charge in the hydrogen. The reason we have that is because the chlorine's more electronegative, it wants to pull more of that shared electron density to itself. If it has more electron density, it's going to have a little bit of a negative charge and the hydrogen's going to be left with a little bit of a positive charge.
So, we can compare this, for example to, molecular hydrogen where they're going to have that complete sharing, so there's not going to be a delta plus or a delta minus, delta is going to be equal to zero on each of the atoms. They are completely sharing their electrons.
And we can also explain this in another way by talking about a dipole moment where we have a charged distribution that results in this dipole, this electric dipole. And we talk about this using the term mu, which is a measurement of what the dipole is. A dipole is always written in terms of writing an arrow from the positive charge to the negative charge. In chemistry, we are always incredibly interested in what the electrons are doing, so we tend to pay attention to them in terms of arrows. Oh, the electrons are going over to the chlorine, so we're going to draw our arrow toward the chlorine atom.
So, we measure this here, so mu is equal to q times r, the distance between the two. And q, that charge is just equal to the partial negative or the partial positive times the charge on the electron. So this is measured in Coulomb meters, you won't ever see a measurement of electronegativity in Coulomb meters -- we tend to talk about it in terms of debye or 1 d, or sometimes there's no units at all, so the d is just assumed, and it's because 1 debye is just equal to this very tiny number of Coulomb meters and it's a lot easier to work with debye's here.
So, when we talk about polar molecules, we can actually extend our idea of talking about polar bonds to talking about polar molecules. So, actually let's start with that on Monday. So everyone have a great weekend. | http://ocw.mit.edu/courses/chemistry/5-111-principles-of-chemical-science-fall-2008/video-lectures/lecture-12/ | 13 |
17 | CHALCOLITHIC ERA in Persia. Chalcolithic (< Gk. khalkos “copper” + lithos “stone”) is a term adopted for the Near East early in this century as part of an attempt to refine the framework of cultural developmental “stages” (Paleolithic, Mesolithic, Neolithic, Bronze, and Iron Ages) and used by students of western European prehistory (E. F. Henrickson,1983, pp. 68-79). In Near Eastern archeology it now generally refers to the “evolutionary” interval between two “revolutionary” eras of cultural development: the Neolithic (ca. 10,000-5500 b.c.e., but varying from area to area), during which techniques of food production and permanent village settlement were established in the highlands and adjacent regions, and the Bronze Age (ca. 3500-1500 b.c.e., also varying with the area), during which the first cities and state organizations arose.
Although archeologists have devoted less attention to the Chalcolithic, it was an era of fundamental economic, social, political, and cultural development, made possible by the economic advances of the Neolithic and providing in turn the essential basis for the innovations of the Bronze Age. The era can be divided into three general phases, Early, Middle, and Late Chalcolithic, approximately equivalent respectively to the Early, Middle, and Late Village periods identified by Frank Hole (1987a; 1987b; for more detailed discussion of the internal chronology of the Persian Chalcolithic, see Voigt; idem and Dyson). Those aspects most directly attested by archeological evidence (primarily demographic and economic) will be emphasized here, with some attention to less clearly identifiable social, political, and ideological trends. Persia is essentially a vast desert plateau surrounded by discontinuous habitable areas, limited in size and ecologically and geographically diverse, few of them archeologically well known, especially in the eastern half of the country. The evidence is highly uneven and drawn primarily from surveys and excavations in western and southwestern Persia.
Settlement patterns. It is remarkable that in so geographically diverse and discontinuous a country a single distinctive pattern of settlement development characterized the Chalcolithic era in most of the agriculturally exploitable highland valleys and lowland plains that have been surveyed. During the early phase most habitable areas were sparsely settled; small, undifferentiated village sites were located near streams or springs. This pattern was essentially an extension of the prevailing Neolithic settlement pattern and in a few areas (e.g., northwestern Iran; Swiny) appears to have continued throughout the Chalcolithic. In the great majority of the arable mountain valleys and lowland plains, however, it developed in several significant ways through the Middle and Late Chalcolithic. The number of villages increased substantially (in many areas strikingly so) at the end of the Early and especially in the Middle Chalcolithic; then, in the Late Chalcolithic the trend was abruptly reversed, and the number of permanent settlements had dropped precipitously by the end of the era. On the Susiana plain, an eastern extension of the Mesopotamian lowlands in southwestern Persia, Hole (1987a, p. 42) recorded sixteen sites of the Early (= Susiana a) and eighty-six of the Middle Chalcolithic (= Susiana d). In the Late Chalcolithic the number declined to fifty-eight (= early Susa A), then thirty-one (= later Susa A), and finally eighteen (= terminal Susa A). In the much smaller and slightly higher adjacent Deh Luran (Dehlorān) plain the pattern was similar but developed somewhat earlier. Fewer than ten settlement sites were recorded from the early phase of Early Chalcolithic (Chogha Mami Transitional phase 5, Sabz phase 8), approximately twenty from the later Early and early Middle Chalcolithic (Khazineh [Ḵazīna] phase 20, Mehmeh 18), and a steady decline through later Middle and Late Chalcolithic, with only a few permanent settlements by the end of the era (Bayat 14, Farukh [Farroḵ] 12, Susa A 5, Sargarab [Sargarāb]/Terminal Susa A 2; Hole, 1987a; idem, 1987b, p. 100). The best survey data available from southern Persia come from the Marvdašt plain in the broad Kor river drainage basin (Sumner, 1972; idem, 1977) and the smaller Fasā and Dārāb plains (Hole, 1987a, pp. 52-55; idem, 1987b, p. 101). In all three areas the overall settlement pattern was the same: The number of villages increased gradually through the Neolithic and the Early Chalcolithic to an impressive peak in the Middle Chalcolithic Bakun (Bakūn) period (e.g., 146 sites in the Kor river basin), only to drop off dramatically during the Late Chalcolithic and Bronze Age levels. In a survey of the Rūd-e Gošk (Kūšk) near Tepe Yahya (Yaḥyā) Martha Prickett (1976; 1986) found a similar pattern, with the peak in the Yahya VA phase and the sharp drop immediately afterward in the Aliabad (ʿAlīābād) phase (both Late Chalcolithic). In the central Zagros highlands of western Persia the three most comprehensively surveyed valleys revealed a generally similar settlement pattern, though the timing of the peak differed somewhat. In the Māhīdašt, one of the broadest and richest stretches of arable level land in the Zagros, alluviation has added as much as 10m to the late prehistoric land surface, and many Chalcolithic sites are undoubtedly still buried (Brookes et al.). Nevertheless, the number of known villages shows a marked increase from the Neolithic (ten in Sarāb) to the Early Chalcolithic; an abrupt and complete change in the ceramic assemblage, with the appearance at seventy sites of J ware, showing definite generic influence of Halaf (Ḥalaf) pottery in neighboring Mesopotamia (See ceramics iv. the chalcolithic period in the zagros), suggests that the increase may have been caused by an influx of people from the north and west. In the Middle Chalcolithic the number of sites at which black-on-buff and related monochrome-painted wares were found rose sharply to a prehistoric peak of 134. A small number of sites yielded pottery from the purely highland Dalma (Dalmā) tradition, indicating another source of external cultural influence (E. F. Henrickson, 1986; idem, 1990; idem and Vitali). Some degree of indirect outside influence from the Ubaid (ʿObayd) culture of lowland Mesopotamia is also apparent in several of the locally made monochrome-painted wares (E. F. Henrickson, 1986; idem, 1990). In the Late Chalcolithic the flourishing village life in the Māhīdašt seems to have declined; only a handful of sites have yielded pottery characteristic of this period (E. F. Henrickson, 1983, chap. 6; idem, 1985b). Either the settled population dropped considerably at this time, owing to emigration, increased mortality, or adoption of a more mobile and less archeologically visible life style like pastoralism, or the monochrome-painted buff-ceramic tradition persisted until the end of the Chalcolithic. Definitive answers await further investigations in the field. In the Kangāvar valley, 100 km east of the Māhīdašt on the great road to Khorasan, the pattern was noticeably different from that in the western and southern Zagros. The number of villages rose from a single Neolithic example, Shahnabad (Šahnābād) on mound C at Seh Gabi (Se Gābī; McDonald) to twenty in the early Middle Chalcolithic (Dalma phase), located almost exclusively near the streams crossing the central valley floor. All these villages were small, typically covering about 0.5 ha. In the Middle and early Late Chalcolithic the number and location of sites remained relatively stable (seventeen in the Seh Gabi phase, twenty-three contemporary with Godin [Gowdīn] VII), even though the ceramics and other aspects of material culture changed abruptly between these two phases. This stability probably reflects a similar stability in subsistence strategy, as well as greater isolation from external cultural influences. Only toward the end of the Late Chalcolithic was there a notable increase in the number of villages (thirty-nine sites contemporary with Godin VI). The delayed and less marked population increase in Kangāvar, anomalous compared to most well-surveyed areas of western Persia, may have resulted from the cooler, drier climate, established from both ancient and modern ecological data and from the marked clustering of sites on the valley floor near sources of irrigation water (E. F. Henrickson, 1983, pp. 9-36, 466-68). Sociopolitical developments and external connections with the lowlands may also have accounted for a local increase or influx of population during the Godin VI period (E. F. Henrickson, forthcoming; Weiss and Young). The smaller and more marginal Holaylān valley south of the Māhīdašt has been more intensively surveyed. Permanent settlement peaked there in the Middle Chalcolithic; subsistence strategies appear to have become more diversified in the Late Chalcolithic, followed by a marked decline in preserved sites of all types. Peder Mortensen (1974; 1976) found three cave sites, one open-air site, and five village settlements dating to the Neolithic, reflecting a diverse and not completely sedentary system in which both the valley floor and the surrounding hills were exploited economically. Neither J nor Dalma wares were found that far south, and the developments in the Early and early Middle Chalcolithic are thus unclear. Eleven sites with Middle Chalcolithic black-on-buff pottery resembling Seh Gabi painted and Māhīdašt black-on-buff wares were recorded, all on the valley floor (Mortensen, 1976, fig. 11). By the early Late Chalcolithic settlement had again been diversified to include two open-air and two village sites in the hills, as well as seven villages on the valley floor, all yielding ceramics related to generic Susa A wares, including black-on-red; the number of sites remained quite stable (Mortensen, 1976, fig. 13, legend erroneously exchanged with that of fig. 12). The sharp decline in settlement occurred later; only two villages on the valley floor, two cave sites, and two open-air camps, all yielding ceramics related to those of Sargarab and Godin VI, are known (Mortensen, 1976, fig. 12), suggesting a destabilization of village life and a concomitant increase in pastoralism in this area, as in others where the same general pattern has been observed (E. F. Henrickson, 1985a).
Modest settlement hierarchies seem to have developed in some highland valleys during the Chalcolithic, though such geological processes as alluviation and water and wind erosion have undoubtedly obscured the evidence in some areas. Normally a few larger villages seem to have grown up among a preponderance of small villages. In the Māhīdašt the average size of sites without heavy overburden was 1.6 ha in the Early and just over 1 ha in the Middle Chalcolithic, but several sites covering more than 3 ha existed in both phases (E. F. Henrickson, 1983, pp. 458-60). Nothing more is known about these sites, as none have been excavated. Tepe Giyan (Gīān) in the Nehāvand valley was a relatively large highland site (in the 3-ha range) from Early Chalcolithic times; seals and copper objects were found there (Contenau and Ghirshman; Hole, 1987a, pp. 87-89). At Godin Tepe, a small town in the Bronze Age (R. Henrickson, 1984), the Chalcolithic is buried under deep Bronze and Iron Age overburden, and it is not known how large or important it was in relation to the rest of Kangāvar during most of that era (Young, 1969; idem and Levine). During the Late Chalcolithic, however, an oval enclosure (Godin V) was located there, the seat of an enclave of people from the lowlands apparently involved in long-distance commodity exchange, contemporary with the latter part of the prosperous period VI occupation at Godin and in Kangāvar generally (Weiss and Young; Levine and Young). Elsewhere in the central Zagros, especially in northeastern Luristan, several large and strategically located Late Chalcolithic sites developed just at the time when the number of smaller settlements was abruptly declining (Goff, 1966; idem, 1971). In the southwestern lowlands of Ḵūzestān the evolution of a settlement hierarchy progressed farther than anywhere else in Chalcolithic Persia. In Dehlorān two settlement centers grew up. In the Farukh phase of the Middle Chalcolithic Farukhabad (Farroḵābād), estimated to have originally covered approximately 2 ha, contained at least one thick-walled, elaborately bonded brick building, constructed on a low platform (Wright, 1981, pp. 19-21), and in the Susa A period of the Late Chalcolithic the large site of Mussian (Mūsīān; Gautier and Lamprey dominated Dehlorān. Farther south, on the Susiana plain, two “primate” settlement centers developed during the Chalcolithic. Chogha Mish (Čoḡā Mīš, q.v.) in the east flourished in the Middle Chalcolithic, when the number of sites on the plain reached its peak; it covered an area of 11 ha and included domestic architecture and at least one large, thick-walled monumental public building with buttresses, containing many small rooms, including a pottery storeroom and a possible flint-working room (Delougaz; Delougaz and Kantor, 1972; idem, 1975; Kantor, 1976a; idem, 1976b). The contemporaneous settlement at Jaffarabad (Jaʿfarābād) was a specialized pottery-manufacturing site with many kilns (Dollfus, 1975). After the demise of Chogha Mish the settlement on the acropolis at Susa in western Susiana gained prominence, developing into the most impressive Chalcolithic center yet known in Persia, with an area of approximately 20 ha. The high platform was about 70 m2 and stood more than 10 m high. Its brick facing was adorned with rows of inset ceramic “nails,” cylinders with flaring heads (Canal, 1978a; idem, 1978b). Fragmentary architectural remains atop the platform suggest storage rooms and a larger structure that may have been a temple (Steve and Gasche) but the evidence for its function is inconclusive (Pollock). Beside one corner of the terrace was a mortuary structure analogous to a mass mausoleum (de Morgan; de Mecquenem; Canal, 1978a), containing an unknown number of burials, recently estimated at 1,000-2,000 (Hole, 1987a, pp. 41-42; idem, 1990). This burial facility was apparently not intended only for the elite: Only some of the burials were in brick-lined tombs, and a wide range of grave goods were included with individual bodies, from ordinary cooking pots to luxury objects, particularly eggshell-thin Susa A fine painted-ware goblets and copper axes (Canal, 1978a; Hole, 1983). The acropolis at Susa was thus a unique multipurpose Chalcolithic settlement and ceremonial center, a focal point for the region. It may not have had a large resident population, but it nevertheless served a series of complex centralizing sociopolitical functions, presumably both religious and secular. Centers like Chogha Mish and Susa, like the late Ubaid center at Eridu, presaged the rise of the first true cities in the Mesopotamian lowlands in the subsequent Uruk period.
Strategies for subsistence. Irrigation appears to have been utilized throughout the arable highland valleys and lowland plains of Persia for the first time during the Middle Chalcolithic. The best-documented area is Dehlorān, where careful collection and interpretation of botanical, settlement, and geomorphological data by several different expeditions have resulted in an unusually clear picture both of flourishing irrigation agriculture and the subsequent abuse of the land and decline of permanent agricultural settlement in the Late Chalcolithic (Hole, Flannery, and Neely; Hole, 1977; Wright, 1975). Direct botanical evidence of Chalcolithic irrigation is not as rich for other sites in Persia, but in surveys of the Māhīdašt (Levine, 1974; idem, 1976; idem and McDonald), Kangāvar (Young, 1974), Susiana (Hole, 1987a; idem, 1987b), Kāna-Mīrzā (Zagarell), the Kor river basin (Sumner, 1983), and elsewhere linear alignment of contemporaneous sites along ancient watercourses provides strong indirect evidence. In the Rūd-e Gošk survey Prickett (1976) also noted a strong association between many Middle Chalcolithic (Yahya VB and VA) sites, on one hand, and alluvial fans and ancient terraces used for flood irrigation. Of course, not all Middle Chalcolithic villages required irrigation; many were located in areas with sufficient rainfall for dry farming.
In the western highlands there is strong evidence of specialized mobile pastoralism, apparently distinct from settled village farming, during the Middle and especially the Late Chalcolithic (E. F. Henrickson, 1985a). It includes the isolated Paṛčīna and Hakalān cemeteries in the Pošt-e Kūh, located far from any ancient village site (Vanden Berghe, 1973; idem, 1974; idem, 1975a; idem, 1975b; idem, forthcoming); an increased number of open-air and cave sites located near sometimes seasonal sources of fresh water, in Holaylān, Ḵorramābād (Wright et al.), the Pošt-e Kūh (Kalleh Nissar [Kalla-Nesār]; Vanden Berghe, 1973), the hinterlands south and east of Susiana, including Īza and Qaḷʿa-ye Tal (Wright, 1987), and the Baḵtīārī region (Zagarell); and the appearance of at least one distinctive pottery type, black-on-red ware, which was widely but sparsely distributed in Luristan, Ḵūzestān, and adjacent areas, probably carried by mobile pastoralists (E. F. Henrickson, 1985a). The pervasive Late Chalcolithic decline in the number of villages provides indirect support for the hypothesis of increased diversification and mobility in subsistence strategies. In areas like the Kor river basin, where this decline appears to have been more gradual, many of the remaining sites are adjacent to natural grazing land, suggesting increased reliance on herding even among villagers (Hole, 1987a, pp. 54-55). Some degree of ecological or climatic deterioration may have contributed to this shift in certain areas, and political and economic pressures from the adjacent lowlands may also have increased (Lees and Bates; Bates and Lees; Adams; E. F. Henrickson, 1985a).
Crafts and “trade.” The Chalcolithic era was distinguished from other eras of prehistory by the variety of painted pottery that was produced, most of it utilitarian and probably made in village homes or by part-time potters who did not earn their livelihoods entirely from their craft. With a few notable exceptions, each highland valley system and lowland plain produced a distinctive ceramic assemblage over time; although there was some resemblance to pottery from nearby areas, typically each assemblage was recognizable as the work of a separate community, with different approaches and expectations. Technical and aesthetic quality, though variable, tended to improve over time, culminating in the Bakun painted ware of the Middle Chalcolithic and the Susa A fine ware of the Late Chalcolithic. Both were produced in prosperous and heavily populated areas during phases in which village settlement had reached or just passed its prehistoric zenith and pronounced settlement hierarchies had developed; their demise was associated with the subsequent rapid decline in permanent village settlement. Both were of extremely fine buff fabric without inclusions, skillfully decorated with a variety of standardized geometric patterns in dark paint; each, however, was characterized by a unique “grammar,” “syntax,” and symbolic “semantics” of design (Hole, 1984). It is not yet clear, however, that either or both of these wares resulted from occupational specialization. Archeological evidence for specialized ceramic production in the Persian Chalcolithic is extremely rare. At Tal-e Bakun, the type site for Bakun painted ware, one Middle Chalcolithic residential area of twelve buildings was excavated (Langsdorff and McCown). Several appear to have been potters’ workshops, in which work tables with nearby clay supplies and storage boxes for ash temper were found. In addition, three large kilns were associated with this group of houses (Langsdorff and McCown, pp. 8-15, figs. 2, 4). Hole (1987b, p. 86) has pointed out that the published plans imply that only one of the kilns was in use at any one lime, which suggests specialized production, most likely of Bakun painted ware, perhaps partially for export: The ware was quite widespread in the Kor river basin and adjacent areas of southern Persia. The technical prowess and artistic sophistication involved are arguments for specialized production, possibly involving full-time artisans. From Susa itself there is no direct evidence of specialized ceramic production in the Susa A period, but many of the sites surveyed in Susiana have yielded remains of kilns and many wasters, evidence of widespread localized pottery production in Middle and Late Chalcolithic times. Although some excavated sites have also revealed houses with kilns (e.g., Tepe Bendebal [Band-e Bāll]; Dollfus, 1983), only one is known to have been devoted exclusively to ceramic production: Middle Chalcolithic (Chogha Mish phase) Jaffarabad (Dollfus, 1975). As with Bakun painted ware, however, the exceptionally high technical and aesthetic quality of Susa A fine ware strongly suggests production by full-time specialists at Susa itself and perhaps at other sites as well.
Wide geographic distribution of a distinctive ware or pottery style does not automatically indicate a centralized network of commodity distribution. The absence of efficient transportation in the Chalcolithic, especially in the highlands, must have precluded Systematic, high-volume ceramic exchange, even between the few relatively highly organized centers. For example, in the early Middle Chalcolithic the full Dalma ceramic assemblage, characterized by painted and impressed wares, was remarkably widespread, dominating the Soldūz-Ošnū area of Azerbaijan and the Kangāvar and Nehāvand valleys of northeastern Luristan. The latter ware also occurred in conjunction with Dalma plain red-slipped ware in the Māhīdašt. This distribution pattern was almost certainly not the result of organized long-distance trade in Dalma pottery, which was not a “luxury” ware and was far too heavy and bulky to have been transported economically through the Zagros mountains, especially in the absence of wheeled vehicles and beasts of burden. Furthermore, Dalma settlement data reveal a strictly village economy with no sociopolitical or economic settlement hierarchy. The wide distribution of the pottery must therefore be explained sociologically, rather than economically, as reflecting the distribution of a people, probably a kin-based ethnic group that may have shared a common dialect or religion and produced a distinctive utilitarian pottery, as well as other visible but perishable items of material culture; these items would have served as group markers, analogous to the distinctive dress and rug patterns of today’s Zagros Kurds (E. F. Henrickson and Vitali). Similar situations in the Early Chalcolithic include the spread of Chogha Mami (Čoḡā Māmī) transitional pottery from eastern Mesopotamia into Dehlorān (Hole, 1977) and probably the appearance of J ware in the Māhīdašt (Levine and McDonald). Any pottery “exchange” over a considerable distance was probably a coincidental result of contact for other reasons; late Middle Chalcolithic-Late Chalcolithic black-on-red ware is a good example (E. F. Henrickson, 1985a). In other instances “related” pottery assemblages from adjacent areas are not identical, which implies that, instead of actual movement of vessels, indirect “exchange” took place involving assimilation of selected elements from an external ceramic style into local tradition. One example is the diluted and locally “edited” influence of Ubaid ceramics on otherwise diverse highland Māhīdašt pottery (E. F. Henrickson, 1983; idem, 1986; idem, 1990) in the Middle and Late Chalcolithic. In the eastern central Zagros and adjacent plateau area a different ceramic tradition, labeled Godin VI in the mountains and Sialk (Sīalk) III/6-7 (Ghirshman, 1938) and Ghabristan (Qabrestān) IV (Majidzadeh, 1976; idem, 1977; idem, 1978; idem, 1981) farther east, developed in the Late Chalcolithic. Other archeological evidence suggests that this particular phenomenon may have coincided with an attempt at organizing a regional economic or sociopolitical entity (E. F. Henrickson, forthcoming). The broad distribution of these distinctive ceramics, taken together with glyptic evidence (E. F. Henrickson, 1988) and the remains in several eastern Luristan valleys of large settlements (Goff, 1971), at least one of which permitted the apparently peaceful establishment of a lowland trading enclave in its midst (Weiss and Young), supports an economic explanation.
The special cases of Susa A fine and Bakun painted ware have been discussed above; as true “art” wares, they are probably the best candidates for medium- to long-distance ceramic exchange in Iranian Chalcolithic, but available data are inconclusive, and strictly local production (probably by specialists at a few sites in each area) cannot be ruled out.
There are almost no archeological data for craft production other than ceramics in Chalcolithic Persia.
Only a few widely scattered examples of copper, stone, and glyptic work have been excavated. There are a number of sources for copper (q.v.) in central Persia, but copper processing is known from only one site of this period, Tal-i Iblis (Tal-e Eblīs) near Kermān (Caldwell, 1967; idem and Shahmirzadi). In Iblis I (Early Chalcolithic) and II (late Middle-Late Chalcolithic) hundreds of slag-stained crucible fragments were recovered, along with chunks of slag and rejected copper ore. Although the accompanying ceramics do not reflect outside contact, the presence of large quantities of pyrometallurgical debris and the remote location near copper sources strongly suggest that the site was established specifically to process locally mined copper ore in quantity for export (Caldwell, p. 34). Sialk, from which copper artifacts were recovered in various Chalcolithic levels (Ghirshman, 1938), was also located in a copper-bearing area, near Kāšān; there is no known direct evidence of copper processing at the site, but cast copper tools and ornaments (e.g., round-sectioned pins) were found (Ghirshman, 1938, pl. LXXXIV). In Chalcolithic Giyan V, west of Sialk in northeastern Luristan, copper objects included borers, small spirals, tubes, rectangular-sectioned pins, and a rectangular axe (Contenau and Ghirshman, pp. 16-45, 64ff.). Only a few other sites have yielded copper objects, including the axes from burial hoards at Susa. Copper thus seems to have been a rare and presumably expensive material throughout the Persian Chalcolithic. Direct, unequivocal evidence for other craft production and exchange (e.g., stone, glyptic, and textile work) is either rare or lacking altogether, though scattered small finds from various houses and graves suggest at least a low level of such craft activity in certain areas during certain phases. The exception is obsidian, which was obtained from Anatolian sources in small quantities throughout the Neolithic and Chalcolithic (see Hole, 1987b, pp. 86-87).
Burial practices. Outside the realm of economics and subsistence available archeological data and their interpretation are extremely problematic. The only evidence consists of sparse and unevenly preserved burials and associated structures and goods (for detailed discussion, see Hole, 1987b; idem, 1990). In the Early Chalcolithic all known highland and lowland burials (fewer than a dozen, from three sites: Seh Gabi, Jaffarabad, and Chogha Mish) are of infants or children, who were deposited under the floors of houses, a possible indication of family continuity and settlement stability. As in the Neolithic, grave goods were limited to a few modest personal items, mainly pots and simple jewelry, suggesting a relatively egalitarian society. These data reflect continuation of the predominant Neolithic pattern in southwestern Persia and in lowland Mesopotamia as well. Burying customs for adults are unknown; the burials must have been extramural, but no Early Chalcolithic cemetery has been identified. In the northern and central Zagros the Early Chalcolithic pattern continued to evolve in the next phase. At Dalma Tepe, Seh Gabi, and Kozagaran (Kūzagarān) children were buried under house floors but were first placed in pots or bowls. In contrast, a completely new burial form developed in Ḵūzestān. At Jaffarabad, Chogha Mish, Jowi (Jovī), and Bendebal infants (and a very few adults out of a relatively large sample) have been found in brick tombs outside the houses. Grave goods still consisted of a few simple utilitarian objects, primarily pots, with nothing to indicate differences in status. In the Pošt-e Kūh just north of Dehlorān abundant data have been recovered from almost 200 stone-lined tomb burials, mostly of adults, in the two pastoralist cemeteries, Parchineh and Hakalan. These cemeteries appear to reflect the adoption of lowland burial customs in the outer ranges of the Zagros, lending support to speculation about migration routes between the two areas and interaction between pastoralists and villagers. Grave goods were limited almost entirely to utilitarian ceramics and a few stone tools, weapons, and pieces of jewelry, insufficient to suggest significant differences in status.
The Late Chalcolithic burial sample is very small, except for the large mortuary at Susa. The few known burials were all of children or infants and generally continued the two Middle Chalcolithic patterns: Those from Seh Gabi and Giyan in the central highlands were in jars or pots without burial goods, though architectural context was unclear at both sites. Two infant burials from lowland Jaffarabad were in mat-lined mud “boxes,” accompanied only by pottery and a single seal; it is impossible to interpret this one instance as a status item. Although the large Susa A burial facility appears to have been unique in Chalcolithic Persia, it nevertheless reflected the Middle-Late Chalcolithic lowland custom of burial in brick tombs, demonstrating a formal standardization in the treatment of the dead: one corpse to a tomb, supine in an extended position. Grave goods were much more elaborate than elsewhere, but, with a few striking exceptions (hoards of copper objects), they, too, seem to have been standardized, consisting primarily of ceramics vessels ranging in quality from utilitarian “cooking pots” to distinctive Susa A fine painted goblets (often in the same tombs). The absence of an excavation record for this part of Susa is frustrating, but, even though the size and architectural elaboration of the site are evidence of its function as a regional center, the burials do not seem to reflect a society in which status differences were structurally the most important; rather, an emphasis on the unity of the regional “community” is suggested. It is possible, however, that only individuals or families of high status were buried at Susa and that the majority of those in the economic “sustaining area” were buried elsewhere, probably near their own homes. If so, then the simple fact of burial at the regional center, rather than elaborate individual tombs or grave goods, would have been the primary mark of high status. The rest of the population of Chalcolithic Persia seems to have lived in egalitarian villages or pastoral groups. Larger local settlement centers, involving development of sociopolitical and economic differences in status, were clearly the exception.
R. M. Adams, “The Mesopotamian Social Landscape. A View from the Frontier,” in C. B. Moore, ed., Reconstructing Complex Societies, Cambridge, Mass., 1974, pp. 1-20.
F. Bagherzadeh, ed., Proceedings of the IInd Annual Symposium on Archaeological Research in Iran, Tehran, 1974.
Idem, ed., Proceedings of the IIIrd Annual Symposium on Archaeological Research in Iran, Tehran, 1975.
Idem, ed., Proceedings of the IVth Annual Symposium on Archaeological Research in Iran, Tehran, 1976.
D. G. Bates and S. H. Lees, “The Role of Exchange in Productive Specialization,” American Anthropologist 79/4, 1977, pp. 824-41.
I. A. Brookes, L. D. Levine, and R. Dennell, “Alluvial Sequence in Central West Iran and Implications for Archaeological Survey,” Journal of Field Archaeology 9, 1982, pp. 285-99.
J. R. Caldwell, ed., Investigations at Tall-i Iblis, Illinois State Museum Preliminary Report 9, Springfield, Ill., 1967.
Idem and S. M. Shahmirzadi, Tal-i Iblis. The Kerman Range and the Beginnings of Smelting, Illinois State Museum Preliminary Report 7, Springfield, Ill., 1966.
D. Canal, “La haute terrasse de l’Acropole de Suse,” Paléorient 4, 1978a, pp. 39-46.
Idem, “La terrasse haute de l’Acropole de Suse,” CDAFI 9, 1978b, pp. 11-55.
G. Contenau and R. Ghirshman, Fouilles du Tépé Giyan près de Néhavend, 1931, 1932, Paris, 1935.
P. Delougaz, “The Prehistoric Architecture at Choga Mish,” in The Memorial Volume of the VIth International Congress of Iranian Art and Archaeology, Oxford, 1972, Tehran, 1976, pp. 31-48.
Idem and H. Kantor, “New Evidence for the Prehistoric and Protoliterate Culture Development of Khuzestan,” in The Memorial Volume of the Vth International Congress of Iranian Art and Archaeology, Tehran, 1972, pp. 14-33.
Idem, “The 1973-74 Excavations at Coqa Mis,” in Bagherzadeh, ed., 1975, pp. 93-102.
G. Dollfus, “Les fouilles à Djaffarabad de 1972 à 1974.
Djaffarabad periodes I et II,” CDAFI 5, 1975, pp. 11-220.
Idem, “Djowi et Bendebal. Deux villages de la plaine centrale du Khuzistan (Iran),” CDAFI 13, 1983, pp. 17-275.
J. E. Gautier and G. Lampre, “Fouilles de Moussian,” MDAFP 8, 1905, pp. 59-149.
R. Ghirshman, Fouilles de Sialk près de Kashan, 1933, 1934, 1937 I, Paris, 1938.
C. Goff, New Evidence of Cultural Development in Luristan in the Late 2nd and Early First Millennium, Ph.D. diss., University of London, 1966.
Idem, “Luristan before the Iron Age,” Iran 9, 1971, pp. 131-52.
E. F. Henrickson, Ceramic Styles and Cultural Interaction in the Early and Middle Chalcolithic of the Central Zagros, Iran, Ph.D. diss., University of Toronto, 1983.
Idem, “The Early Development of Pastoralism in the Central Zagros Highlands (Luristan),” Iranica Antiqua 20, 1985a, pp. 1-42.
Idem, “An Updated Chronology of the Early and Middle Chalcolithic of the Central Zagros Highlands, Western Iran,” Iran 23, 1985b, pp. 63-108.
Idem, “Ceramic Evidence for Cultural Interaction between Chalcolithic Mesopotamia and Western Iran,” in W. D. Kingery, ed., Technology and Style. Ceramics and Civilization II, Columbus, Oh., 1986, pp. 87-133.
Idem, “Chalcolithic Seals and Sealings from Seh Gabi, Central Western Iran,” Iranica Antiqua 23, 1988, pp. 1-19.
Idem, “Stylistic Similarity and Cultural Interaction between the ʿUbaid Tradition and the Central Zagros Highlands,” in E. F. Henricksen and I. Thuesen, eds., 1990, pp. 368-402.
Idem, “The Outer Limits. Settlement and Economic Strategies in the Zagros Highlands during the Uruk Era,” in G. Stein and M. Rothman, eds., Chiefdoms and Early States in the Near East. The Organizational Dynamics of Complexity, Albuquerque, forthcoming.
Idem and I. Thuesen, eds., Upon This Foundation. The ʿUbaid Reconsidered, Copenhagen, Carsten Niebuhr Institute Publication 8, 1990.
Idem and V. Vitali, “The Dalma Tradition. Prehistoric Interregional Cultural Integration in Highland Western Iran,” Paléorient 13/2, 1987, pp. 37-46.
R. C. Henrickson, Godin III, Godin Tepe, and Central Western Iran, Ph.D. diss., University of Toronto, 1984.
F. Hole, Studies in the Archaeological History of the Deh Luran Plain. The Excavation of Chogha Sefid, The University of Michigan Museum of Anthropology Memoirs 9, Ann Arbor, Mich., 1977.
Idem, “Symbols of Religion and Social Organization at Susa,” in L. Braidwood et al., eds., The Hilly Flanks and Beyond. Essays on the Prehistory of Southwestern Asia, The University of Chicago Oriental Institute Studies in Ancient Oriental Civilization 36, Chicago, 1983, pp. 233-84.
Idem, “Analysis of Structure and Design in Prehistoric Ceramics,” World Archaeology, 15/3, 1984, pp. 326-47.
Idem, “Archaeology of the Village Period,” in F. Hole, ed., 1987a, pp. 29-78.
Idem, “Settlement and Society in the Village Period,” in F. Hole, ed., 1987b, pp. 79-106.
Idem, “Patterns of Burial in the Fifth Millennium,” in E. F. Henricksen and I. Thuesen, eds. (forthcoming).
Idem, ed., The Archaeology of Western Iran. Settlement and Society from Prehistory to the Islamic Conquest, Washington, D.C., 1987.
F. Hole, K. V. Flannery, and J. A. Neely, Prehistory and Human Ecology of the Deh Luran Plain, The University of Michigan Museum of Anthropology Memoirs 1, Ann Arbor, Mich., 1969.
H. Kantor, “The Excavations at Coqa Mish, 1974-75,” in Bagherzadeh, ed., 1976a, pp. 23-41.
Idem, “Prehistoric Cultures at Choga Mish and Boneh Fazili (Khuzistan),” in Memorial Volume of the VIth International Congress on Iranian Art and Archaeology, Oxford, 1972, Tehran, 1976b, pp. 177-94.
A. Langsdorff and D. E. McCown, Tal-i Bakun A, The University of Chicago Oriental Institute Publications 59, Chicago, 1942.
S. H. Lees and D. G. Bates, “The Origins of Specialized Pastoralism. A Systemic Model,” American Antiquity 39, 1974, pp. 187-93.
L. D. Levine, “Archaeological Investigations in the Mahidasht, Western Iran, 1975,” Paléorient 2/2, 1974, pp. 487-90.
Idem, “Survey in the Province of Kermanshahan 1975.
Mahidasht in the Prehistoric and Early Historic Periods,” in Bagherzadeh, ed., 1976, pp. 284-97.
Idem and M. M. A. McDonald, “The Neolithic and Chalcolithic Periods in the Mahidasht,” Iran 15, 1977, pp. 39-50.
L. D. Levine and T. C. Young, Jr., “A Summary of the Ceramic Assemblages of the Central Western Zagros from the Middle Neolithic to the Late Third Millennium B.C.,” in J. L. Huot, ed., Préhistoire de la Mésopotamie. La Mésopotamie préhistorique et l’exploration récente du Djebel Hamrin, Paris, 1987, pp. 15-53.
M. M. A. McDonald, An Examination of Mid-Holocene Settlement Patterns in the Central Zagros Region of Western Iran, Ph.D. diss., University of Toronto, 1979.
Y. Majidzadeh, The Early Prehistoric Cultures of the Central Plateau of Iran. An Archaeological History of Its Development during the Fifth and Fourth Millennia B.C., Ph.D. diss., The University of Chicago, 1976.
Idem, “Excavations in Tepe Ghabristan. The First Two Seasons, 1970 and 1971,” Marlik 2, 1977, pp. 45-61.
Idem, “Corrections of the Chronology for the Sialk III Period on the Basis of the Pottery Sequence at Tepe Ghabristan,” Iran 16, 1978, pp. 93-101.
Idem, “Sialk III and the Pottery Sequence at Tepe Ghabristan,” Iran 19, 1981, pp. 141-46.
R. de Mecquenem, “Fouilles préhistoriques en Asie occidentale. 1931-1934,” l’Anthropologie 45, 1935, pp. 93-104.
J. de Morgan, “Observations sur les couches profondes de l’Acropole de Suse,” MDP 13, 1912, pp. 1-25.
P. Mortensen, “A Survey of Prehistoric Settlements in Northern Luristan,” Acta Archaeologica 45, 1974, pp. 1-47.
Idem, “Chalcolithic Settlements in the Holailan Valley,” in Bagherzadeh, ed.,1976, pp. 42-62.
S. Pollock, “Power Politics in the Susa A Period,” in E. F. Henricksen and I. Thuesen, eds. (forthcoming).
M. E. Prickett, “Tepe Yahya Project. Upper Rud-i Gushk Survey,” Iran 14, 1976, pp. 175-76.
Idem, Man, Land, and Water. Settlement Distribution and the Development of Irrigation Agriculture in the Upper Rud-i Gushk Drainage, Southeastern Iran, Ph.D. diss., Harvard University, 1986.
M. J. Steve and H. Gasche, L’Acropole de Suse, MDAFI 46, 1971.
W. Sumner, Cultural Development in the Kur River Basin, Iran. An Archaeological Analysis of Settlement Patterns, Ph.D. diss., University of Pennsylvania, Philadelphia, 1972.
Idem, “Early Settlements in Fars Province, Iran,” in L. D. Levine and T. C. Young, Jr., eds., Mountains and Lowlands. Essays in the Archaeology of Greater Mesopotamia, Malibu, Calif., 1977, pp. 291-305.
S. Swiny, “Survey in Northwest Iran, 1971,” East and West 25/1-2, 1975, pp. 77-96.
L. Vanden Berghe, “Excavations in Luristan. Kalleh Nissar,” Bulletin of the Asia Institute of Pahlavi University 3, 1973a, pp. 25-56.
Idem, “Le Luristan avant l’Age du Bronze. Le nécropole du Hakalan,” Archaeologia 57, 1973b, pp. 49-58.
Idem, “Le Lorestan avant l’Age du Bronze. La nécropole de Hakalan,” in Bagherzadeh, ed., 1974, pp. 66-79.
Idem, “Fouilles au Lorestan, la nécropole de Dum Gar Parchineh,” in Bagherzadeh, 1975a, pp. 45-62.
Idem, “La nécropole de Dum Gar Parchinah,” Archaeologia 79, 1975b, pp. 46-61. Idem, Mission
Archéologique dons le Pusht-i Kuh, Luristan. IXe Campagne 1973. La nécropole de Dum Gar Parchinah (Rapport préliminaire), 2 vols., forthcoming.
M. Voigt, “Relative and Absolute Chronologies for Iran between 6500 and 3500 cal. B. C.,” in O. Aurenche, J. Evin, and F. Hours, eds., Chronologies in the Near East. Relative Chronologies and Absolute Chronology. 16,000-4,000 B.P., British Archaeological Reports International Series 379, Oxford, 1987, pp. 615-46.
Idem and R. H. Dyson, Jr., “The Chronology of Iran, ca. 8000-2000 B.C.,” in R. W. Ehrich, ed., Chronologies in Old World Archaeology, Chicago, forthcoming.
H. Weiss and T. C. Young, Jr., “The Merchants of Susa. Godin V and Plateau-Lowland Relations in the Late Fourth Millennium B.C.,” Iran 13, 1975, pp. 1-18.
H. T. Wright, An Early Town on the Deh Luran Plain. Excavations at Tepe Farukhabad, The University of Michigan Museum of Anthropology Memoirs 13, Ann Arbor, Mich., 1981.
Idem, “The Susiana Hinterlands during the Era of Primary State Formation,” in F. Hole, ed., 1987, pp. 141-56.
Idem et al., “Early Fourth Millennium Developments in Southwestern Iran,” Iran 13, 1975, pp. 129-48.
T. C. Young, Jr., Excavations at Godin Tepe, Royal Ontario Museum Art and Archaeology Occasional Papers 17, Toronto, 1969.
Idem, “An Archaeological Survey in Kangavar Valley,” in Bagherzadeh, ed., 1975, pp. 23-30.
Idem and L. D. Levine, Excavations at the Godin Project. Second Progress Report, Royal Ontario Museum Art and Archaeology Occasional Papers 26, Toronto, 1974.
A. Zagarell, The Prehistory of the Northeast Baḫtiyari Mountains, Iran, TAVO, Beihefte B42, Wiesbaden, 1982.
(Elizabeth F. Henrickson)
Originally Published: December 15, 1991
Last Updated: October 13, 2011
This article is available in print.
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16 | distribution of wealth and incomeArticle Free Pass
distribution of wealth and income, the way in which the wealth and income of a nation are divided among its population, or the way in which the wealth and income of the world are divided among nations. Such patterns of distribution are discerned and studied by various statistical means, all of which are based on data of varying degrees of reliability.
Wealth is an accumulated store of possessions and financial claims. It may be given a monetary value if prices can be determined for each of the possessions; this process can be difficult when the possessions are such that they are not likely to be offered for sale. Income is a net total of the flow of payments received in a given time period. Some countries collect statistics on wealth from legally required evaluations of the estates of deceased persons, which may or may not be indicative of what is possessed by the living. In many countries, annual tax statements that measure income provide more or less reliable information. Differences in definitions of income—whether, for example, income should include payments that are transfers rather than the result of productive activity, or capital gains or losses that change the value of an individual’s wealth—make comparisons difficult.
In order to classify patterns of national wealth and income, a basis of classification must be determined. One classification system categorizes wealth and income on the basis of the ownership of factors of production: labour, land, capital, and, occasionally, entrepreneurship, whose respective forms of income are labeled wages, rent, interest, and profit. Personal distribution statistics, usually developed from tax reports, categorize wealth and income on a per capita basis.
Gross national income (GNI) per capita provides a rough measure of annual national income per person in different countries. Countries that have a sizable modern industrial sector have a much higher GNI per capita than countries that are less developed. In the early 21st century, for example, the World Bank estimated that the per-capita GNI was approximately $10,000 and above for the most-developed countries but was less than $825 for the least-developed countries. Income also varies greatly within countries. In a high-income country such as the United States, there is considerable variation among industries, regions, rural and urban areas, females and males, and ethnic groups. While the bulk of the U.S. population has a middle income that is derived largely from earnings, wages vary considerably depending on occupation. (See also gross national product, gross domestic product.)
A significant proportion of an economy’s higher incomes will derive from investment rather than earnings. It is often the case that the higher the income, the higher the investment-derived portion tends to be. Because most fortunes require long periods to accumulate, the existence of a class of very wealthy persons can result from the ability of those persons to retain their fortunes and pass them on to descendants. Earned incomes are influenced by a different kind of inheritance. Access to well-paid jobs and social status is largely the product of education and opportunity. Typically, therefore, well-educated children of wealthier parents tend to retain their parents’ status and earning power. A dynamic economy, however, increases the likelihood of attaining wealth and status through individual effort alone.
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42 | US History/War, Nationalism, and Division
The War of 1812
Precursors to the War
By the time James Madison took office as president in 1809, the U.S. was still a young nation. Though the war for independence was fought and won, culminating in the Treaty of Paris in 1783, problems revolving around U.S. sovereignty continued to be a source of contention between the United States and Great Britain. By 1812, the U.S military Academy at West Point, founded in 1802, had produced only eighty-nine regular officers. Senior army officers were aged Revolutionary War Veterans or political appointees. Nor did the United States succeed at mustering sufficient forces. The governments efforts to lure recruits, with sign up- bonuses and promises of three months pay and rights to purchase 160 acres of western land upon discharge, met with mixed success. This was especially true on the American frontier (remember, the British had agreed to recognize all of the land from the Atlantic Ocean to the Mississippi River, except for Spanish Florida) and on the high seas, where American sailors were pressed into service in the British Royal Navy, as the British were waging war against Napoleonic France. The reason for doing this was so the British could find and recover seamen who had defected from the British Navy to join (a relatively easier) life on the High Seas with the Americans. The British would raid American ships (such as the Chesapeake) claiming to look for British deserters. When American refused to allow the British to seize ships this resulted in 18 Americans wounded. This upset a lot of Americans who pressed Jefferson by anonymous letter for the war with Britain. Further, the British had recruited Indians, such as Tecumseh, to aggravate American settlers and even continued to maintain forts on American soil. The British encouraged Native American tribes to harass American settlers. The British took interest in the Ohio Valley and Kentucky region due to the fur trade with the western world.
The British further enraged the Americans with their refusal to recognize U.S. neutrality in Britain's war with France. The British did not want the United States to engage in trade with France, even though Americans believed that they had the right to trade with whomever they wished.
In addition, many Americans wanted to push the British Empire off of the North American continent altogether. President Madison and his advisers believed a conquest of Canada would be quick and easy, believing that the British would hand the Americans the land because of their war with Napoleon. Former President Thomas Jefferson himself even stated that "the acquisition of Canada this year, as far as the neighborhood of Quebec, will be a mere matter of marching, and will give us the experience for the attack on Halifax, the next and final expulsion of England from the American continent.
Politics of the War
As was stated above, former President Jefferson and current President Madison, both Democratic-Republicans, supported the war to end British aggravation on both the frontier and the high seas, with the hope of taking over Canada from the British. However, New England Federalists opposed the war, which was driven by Southern and Western desires for more land. The war was highly unpopular in New England because the New England economy relied heavily on trade, especially with Great Britain.
A Declaration of War was passed by Congress by an extremely small margin in the summer of 1812. Across the Atlantic, meanwhile, Prime Minister Spencer Perceval had been shot and killed, putting Lord Liverpool, who wanted to improve relations with the United States, in charge of the government. He repealed the orders of impressment, but by then, it was already too late. The war had begun.
War of 1812
The war of 1812 did not begin badly for the Federalists, who benefited from anti-war sentiment. They joined renegade Democratic Republicans in supporting New York City mayor Dewitt Clinton for president in the election of 1812. Clinton lost to President Madison by 128 to 89 votes--a respectable showing against a wartime president and the federalists gained some congressional seats and carried many local elections. But the south and the west areas that favored the war remained solidly Democratic Republican. Both sides were rather unprepared to wage a war. The British did not have many troops in British North America at the time (some 5,000 or so), and meanwhile the British war against Napoleon continued in continental Europe as the British blockaded most of the European coastline.
The American military was still unorganized and undisciplined compared to the British military. Militias in New England and New York often refused to fight outside their own states. Desperate for soldiers, New York offered them to free the slaves who enlisted, and compensation to their owners, and the U.S Army made the same offer to slaves in the Old Northwest and in Canada. In Philadelphia black leaders formed a black brigade to defend the city, but in the deep south fear of arming slaves kept them out of the military in New Orleans, where a free black militia dated back to Spanish control of Louisiana. The British on the other hand recruited slave by promising freedom, and exchange for service. The regular army consisted of around 12,000 men, but the state militias were often unwilling to fight outside state lines (and often retreated when they did). This, combined with some difficult losses early on and the war's high level of unpopularity in New England made the war effort much more difficult than President Madison originally imagined.
The Atlantic Theater
The British navy was by far the preeminent naval force in the world. They dominated the high seas. By contrast, the U.S. Navy was not even 20 years old yet and had a mere 22 vessels. The British plan was to protect its shipping in Canada while blockading major American ports.
However, there were a series of American naval victories on the Atlantic at this early stage of the war. On August 19, the USS Constitution engaged HMS Guerriere. The battle was held off the coast of Nova Scotia became the first naval encounter. The HMS Guerriere was led by Captain Dacres who states who was really confident that the British navy could take the U. S Constitution, "There is a Yankee frigate in 45 minutes she surely ours take her in 15 minutes and I promise you 4 months pay." After being 25 ft in distance USS Constitution opened fire with cannon and grape shots. In the midst of the battle, a cannonball fired from Guerriere hit the Constitution's in the side, causing one American seaman to exclaim "Huzzah! Her sides are made of iron!" The Guerriere, which had been instrumental in enforcing the British blockade, lost decisively. Her crew was brought on board as prisoners. When it was realized that Guerriere could not be salvaged, it was set fire and blown up. When Captain Hull of the USS Constitution reached Boston with the news, joy broke out. In October of the same year, Constitution sailed under Captain William Bainbridge and won another victory off the coast of Brazil against HMS Java, which was also rendered unsalvageable while the Constitution remained unharmed. The USS Constitution won the nickname "Old Ironsides" in some of the first victories against Great Britain on the high seas. The victory led from General Hull sparked new hope to the Americans and also redeemed them from the lost at the battle at Fort Dearborn, Ohio leaving General Hull wounded and force to surrender August 15, 1812.
Captain Stephen Decatur, who gained fame during the Barbary War, was also responsible for early naval victories. On October 25, 1812, Captain Decatur, commanding the USS United States, captured the HMS Macedonian. And in January 1813, Captain David Porter sailed the USS Essex into the Pacific to aggravate British shipping in retaliation for harassment of British whaling ships on the American whaling industry. Essex inflicted some $3 million in damages to the British whaling industry before finally being captured off the coast of Chile on March 28, 1814.
Back in on the Atlantic Coast, meanwhile, Sir John Coape Sherbrooke embarked on what was known as the Penobscot Expedition in September 1814 with 500 British sailors off the coast of Maine (then part of Massachusetts), a main hub for smuggling between the British and Americans. During this period, lasting 26 days, Sir Sherbrooke raided and looted several cities and destroyed 17 American vessels, won the Battle of Hampden and occupied Castine for the remainder of the war.
The Great Lakes/Canadian/Western Theater
The Western theater of the war was mostly fought in the Michigan, Ohio, and the Canadian border area. Geography dictated the military operations that would take place in west. Primarily around Lake Erie, Niagara River, Lake Ontario, Saint Lawrence River, and Lake Champlain.
Chesapeake Campaign
The Chesapeake Bay Region was a center of trade, commerce and government during the eighteenth and nineteenth centuries. It became a target of British Military strategy during the War of 1812.The British brought war into the Chesapeake area in 1813 and 1814. On July 4, 1813 Joshua Barney convinced the Navy Department to build twenty barges to protect the Chesapeake Bay. These barges were successful at harassing the Royal Navy, but in the end proved useless in the British campaign that led to "Burning of Washington". The White House and other structures were left ablaze all night and the President and his Cabinet fled D.C. This attack was a diversion by the British and the major battle would take place in 1814 in Baltimore. . This battle is where Francis Scott Key who was detained on a British ship watching the bombardment of Fort McHenry, aboard the British ship Key wrote the verses to The Star Spangled Banner the next morning, this song would become the National Anthem in 1931. What the Chesapeake campaign did was make the Americans realize that they were not a global super power and now they were losing a war because of their arrogance.Despite some victories on the Atlantic by the USS Constitution, USS Wasp, and USS United States of the U.S. Navy could not match the powerful British Royal Navy. The British blockaded nearly every American port on the Atlantic and Gulf coasts. The British had America so blockaded that that U.S. trade declined to nearly 90% in 1811. This major loss of funds threatened to bankrupt the federal government and cut off New England from British Embargo.
The Southern Theater
Connected to the War of 1812 was the Creek War in the South. The Creeks were supported by the British, and in March 1814, General Andrew Jackson and General John Coffee led a force comprised of about 2,000 Tennessee militiamen, Choctaw, Cherokee, and U.S. regulars in a war against the Creek Indians. Out of 1,000 Creeks, led by Chief Menawa, 800 were killed at the Battle of Horseshoe Bend. Only 49 of Jackson's forces were killed. Jackson pursued the remaining Creeks until they surrendered.
At the end of the year 1814, General Jackson was on the move again, this time to New Orleans, Louisiana, to defend against invading British forces. In one of the greatest battles of the war, Jackson decisively routed the British forces. The British army took a hit of 1,784 killed; the Americans lost merely 210. The British forces left New Orleans, and the battle propelled General Jackson to hero status, despite the fact that the war was over. Word had not yet reached the combatant forces that a peace had been signed.
Hartford Convention
New England merchants and shippers had already been upset about the trade policies of the Jefferson administration (Embargo Act of 1807) and the Madison administration (Non-Intercourse Act of 1809), and had wholly opposed going to war with Great Britain in the first place due to the potential damage to New England industry. Thus, the Federalist Party, which had been weakened at the end of the Adams administration, found resurgence in popularity among the citizens of New England states.
With trade illegalized and a British blockade, New England states, particularly Massachusetts and Connecticut, felt the brunt of President Madison's war-time policies. This includes what many New Englanders may have perceived as an attack on their states' sovereignty, as Madison maintained executive control over the military defense of New England rather than allowing governors to take control.
On October 10, 1814, the Massachusetts legislature voted for delegates from all five New England states to meet on December 15 in Hartford, Connecticut, to discuss constitutional amendments pertaining to the interests of New England states.
Twenty-six delegates gathered in Hartford. The meetings were held in secret and no records were kept. The Hartford Convention concluded with a report stating that states had a duty and responsibility to assert their sovereignty over encroaching and unconstitutional federal policy. In addition, a set of proposed Constitutional amendments was established, including:
- Prohibition of trade embargos lasting longer than 60 days;
- 2/3rds majority in Congress for declaration of offensive war, admission of new states, and interdiction of foreign commerce;
- Rescinding 3/5ths representation of slaves (perceived as an advantage to the South);
- One-term limit for the President of the United States; and
- A requirement that each succeeding president be from a different state than his predecessor.
While some delegates may have desired secession from the Union, no such proposal was adopted by the Convention.
Three commissioners from Massachusetts were sent to Washington, DC, to negotiate these terms in February 1815, but news that the war had ended and of General Jackson's victory at New Orleans preceded them. The act was perceived by many as disloyal, and the commissioners returned to Massachusetts. The Hartford Convention added to the ultimate decline of the Federalist Party.
Second Barbary War
Following the First Barbary War, the United States focused on the situation developing with Great Britain, giving the pirate states of the Barbary Coast opportunity to not follow the terms of the treaty ending that war. The U.S., not having the military resources to devote to the region, was forced to pay ransoms for the crew. The British expulsion of all U.S. vessels from the Mediterranean during the War of 1812 further emboldened the pirate states, and Umar ben Muhammad, the Dey of Algiers, expelled U.S. Consular Tobias Lear, declaring war on the United States for failing to pay tribute. Again, the situation went unaddressed due to the lack of U.S. military resources in the area.
After the end of the War of 1812, however, the U.S. was able to focus on American interests in North Africa. On March 3, 1815, Congress authorized use of naval force against Algiers, and a force of ten ships was deployed under the commands of Commodores Stephen Decatur, Jr. and William Bainbridge. Decatur's squadron was the first to depart to the Mediterranean on May 20.
Commodore Decatur quickly led the squadron to decisive victories over the Algiers, capturing two Algerian-flagged ships en route to Algiers. By the end of the month of June, Decatur reached Algiers and demanded compensation or threatened the Dey's destruction. The Dey capitulated, and a treaty was signed in which the Algerian ships were returned in exchange for American captors (of which there were approximately ten), several Algerian captors were returned in exchange for several European captors, $10,000 was paid for seized shipping, and guarantees were made to end the tribute payments and grant the United States full shipping rights.
James Monroe Presidency and The Era of Good Feelings
Opposition to the War of 1812 and the Hartford Convention terminally damaged the Federalists as a viable political party, even portraying the party as traitorous. The last serious Federalist candidate Rufus King ran for the presidency in 1816, losing to James Madison's Secretary of State James Monroe. The party disbanded in 1825.
Indeed following the war, a new wave of nationalism spread across the United States. Previously, citizens of the United States tended to view themselves as citizens of their individual states (i.e. New Yorkers or Georgians) before they viewed themselves as Americans.
The wave of national pride and the lull in partisanship in the wake of defeating the British Empire led to what journalist for Boston's Columbian Sentinal Benjamin Russell perceived to be an Era of Good Feelings as the newly elected President Monroe came through on a good will tour in 1817.
American System
Riding on the wave of newfound national pride, politicians such as Henry Clay of Kentucky, John C. Calhoun of South Carolina, and John Q. Adams of Massachusetts, following in Alexander Hamilton's footsteps, pushed an agenda to strengthen and unify the nation. The system, which came to be known as the American System, called for high tariffs to protect American industry and high land prices to generate additional federal revenue. The plan also called for strengthening the nation's infrastructure, such as roads and canals, which would be financed by tariffs and land revenue. The improvements would make trade easier and faster. Finally, the plan called for maintaining the Second Bank of the United States (chartered in 1816 for 20 years) to stabilize the currency and the banking system, as well as the issuance of sovereign credit. Congress also passed a protective tariff to aid industries that had flourished during the war of 1812 but were now threatened by the resumption of over seas trade. The Tariff of 1816 levied taxes on imported woolens and cottons, as well as on iron,leather,hats, papers,and sugar.
Although portions of the system were adopted (for example, 20-25% taxes on foreign goods, which encouraged consumption of relatively cheaper American goods), others met with roadblocks. Namely, this was true of the infrastructure proposals. The Constitutionality was called into question on whether or not the federal government had such power. Despite this, two major infrastructure achievements were made in the form of the Cumberland Road and the Erie Canal. The Cumberland Road stretched between Baltimore and the Ohio River, facilitating ease of travel and providing a gateway to the West for settlement. The Erie Canal extended from the Hudson River at Albany, New York, to Buffalo, New York, at Lake Erie, thus vastly improving the speed and efficiency of water travel in the northeast.
Opposition to the American System mostly came from the West and the South. Clay argued, however, that the West should support the plan because urban workers in the northeast would be consumers of Western food, and the South should support it because of the market for the manufacture of cotton in northeastern factories. The South, however, strongly opposed tariffs and had a strong market for cotton, anyway.
In short, the American System met with mixed results over the 1810s and 1820s due to various obstacles, but in the end, American industry benefited, and growth ensued.
Industrial Revolution
The Industrial Revolution was from the 18th to 19th century which made major changes in agriculture, manufacturing, mining, transportation, and technology. The industrial revolution began in England and slowly made its way over to the Americas.
Panic of 1819
Following the War of 1812, in addition to the relative absence of partisanship, the United States experienced a period of economic growth. However, around the same time the partisanship returned to Washington, the U.S. economy began to experience its first major financial crisis. Unlike the downturns of the 1780s and 1790s, this downturn originated primarily in the United States, and caused foreclosures, bank failures, unemployment, and reductions in agricultural and manufacturing output.
Adams-Onis Treaty of 1819
Due to the act of purchasing the Louisiana territory in 1803, the Adams-Onis Treaty in 1819 (purchasing Florida territory), and the incorporation of the northern territories of Mexico into the United States in 1847 (Mexican Cession), the number of Catholics in the United States nearly doubled.
Monroe Doctrine and Foreign Affairs
On December 2, 1823, President Monroe introduced the most famous aspect of his foreign policy in his State of the Union Address to Congress. The Monroe Doctrine, as it came to be called, stated that any further attempts by European powers to interfere in the affairs of the nations of the Western hemisphere (namely Latin America) would be seen as an act of aggression against the United States, requiring a U.S. response. The Monroe Doctrine came about as a result of U.S. and British fears the Spain would attempt to restore its power over former colonies in Latin America. President Monroe essentially sent notice that America, both North and South, was no longer open to colonization by European powers.
The fact that the U.S. was still a young nation with very little naval power meant that the warning went largely ignored by the major powers. Despite this, the British approved of the policy and largely enforced it as part of the Pax Britannica, whereby the British Navy secured the neutrality of the high seas. It was mainly through this support, rather than the Monroe Doctrine exclusively, which secured and maintained the sovereignty of Latin American nations.
Even so, the Monroe Doctrine was met with praise by Latin American leaders, despite the fact that they knew that the United States realistically could not enforce it without the backing of the British. In 1826, Latin American revolutionary hero Simón Bolívar called for the first Pan-American conference in Panama, and an era of Pan-American relations commenced.
Seminole War
Chief Neamathla of the Mikasuki at Fowltown engaged in a land dispute with the commander at Fort Scott, General Edmund Pendleton Gaines. The land had been ceded by the Creek at the Treaty of Fort Jackson, however the Mikasuki did not consider themselves Creek and so wished to exert sovereignty over the area, believing the Creek did not have right to cede Mikasuki land. In November 1817, a force of 250 men was sent by General Gaines to capture Neamathla, but was driven back. A second attempt in the same month turned out successful, and the Mikasuki people were driven from Fowltown.
A week after the attack on Fowltown, a military boat transporting supplies, sick soldiers, and the families of soldiers (whether or not children were on board is not clear) to Fort Scott was attacked on the Apalachicola River. Most of the passengers on board were killed, with one woman captured and six survivors making it to Fort Scott.
General Gaines had been ordered not to invade Spanish Florida (save for small incursions). However, after word of the Scott massacre reached Washington, DC, Gaines was ordered to invade Florida in pursuit of Seminoles, but not to attack Spanish installations. However, Gaines had been ordered to eastern Florida to deal with piracy issues there, so Secretary of War John C. Calhoun ordered General Andrew Jackson, hero of the War of 1812, to lead the invasion.
General Jackson gathered his forces at Fort Scott in March 1818. The force consisted of 800 regulars, 1,000 Tennessee volunteers, 1,000 Georgia militia, and 1,400 friendly Creek warriors. Jackson's force entered Florida on March 13, following the Apalachicola River and constructing Fort Gadsden. The Indian town of Tallahassee was burned on March 31 and the town of Miccosukee was taken the next day. The American and Creek forces left 300 Indian homes devastated in their wake, reaching the Spanish fort of St. Marks on April 6, capturing it.
The American force left St. Marks and continued to attack Indian villages, capturing Alexander George Arbuthnot, a Scottish trader who worked out of the Bahamas and supplied the Indians, and Robert Ambrister, a former Royal Marine and self-appointed British agent, as well as the Indian leaders Josiah Francis and Homathlemico. All four were eventually executed. Jackson's forces also attacked villages occupied by runaway slaves along the Suwannee River.
Having declared victory, Jackson sent the Georgia militia and Creek warriors home, sending the remaining army back to St. Marks, where he left a garrison before returning to Fort Gadsden. On May 7, he marched a force of 1,000 to Pensacola where he believed the Indians were gathering and being supplied by the Spanish, against the protests of the governor of West Florida, who insisted that the Indians there were mostly women and children. When Jackson reached Pensacola on May 23, the governor and the Spanish garrison retreated to Fort Barrancas. After a day of exchanging cannon fire, the Spanish surrendered, and Colonel William King was named military governor of West Florida. General Jackson went home to Tennessee -- and prepared for his presidential run in 1824.
The 1824 Election and Presidency of John Q. Adams
With the dissolution of the Federalist Party, there were no organized political parties for the 1824 presidential election, and four Democratic-Republicans vied for the office. The Tennessee legislature and a convention of Pennsylvania Democratic-Republicans had nominated General-turned-Senator Andrew Jackson for president in 1822 and 1824, respectively. The Congressional Democratic-Republican caucus (the traditional way to nominate a president) selected Treasury Secretary William H. Crawford for president and Albert Gallatin for vice president. Secretary of State John Q. Adams, son of the former President Adams, and House Speaker Henry Clay also joined the contest. It is widely believed that Crawford would have won had he not suffered a debilitating stroke during the course of the election.
When the electoral votes were cast and counted, it turned out that no candidate had a majority of votes. Jackson had won the most votes, but Constitutionally, a plurality was not good enough, and the vote for the top three candidates went to the House of Representatives. Clay, with the least amount of votes, was ineligible, but still wielded a lot of power as speaker of the house. And since Clay had a personal dislike of Jackson and supported many of Adams' policies, which were similar to his American System, Clay threw his support to Adams, and Adams won the presidency, much to the chagrin of Jackson, who had won the most electoral and popular votes. After Adams appointed Clay as secretary of state, Jackson's supporters protested that a corrupt bargain had been struck.
The 1824 helped in the resurgence of political parties in America. Jackson's followers, members of the Democratic Party, were known as Jacksonians; Adams, Clay, and their supporters established the National Republican Party. Partisan politics was back in style in Washington, DC.
During Adams' term as president, he undertook an ambitious domestic agenda, implementing many aspects of the American System, such as extending the Cumberland Road and several canal projects like the Chesapeake and Ohio Canal, the Delaware and Chesapeake Canal, the Portland to Louisville Canal, the connection of the Great Lakes to the Ohio River system, and the enlargement and rebuilding of the Dismal Swamp Canal in North Carolina. He worked diligently to upgrade and modernize infrastructure and internal improvements, such as roads, canals, a national university, and an astronomical observatory. These internal improvements would be funded by tariffs, an issue which divided the Adams administration. While Secretary Clay most certainly supported tariffs, Vice President John C. Calhoun opposed. This turned out to be a source of contention within the administration.
Unfortunately for President Adams, his agenda met with many roadblocks. First of all, Adams' ideas were not very popular, even from within his own party. But a major reason Adams had a tough time enacting his agenda was because the Jacksonians were still quite upset about the 1824 elections. In 1827, the Jacksonians won control of Congress, making it even more difficult. In addition, Adams did not believe in removing administration officials from office, except for incompetence, including those who may be political opponents. As a result, many administration officials were, in fact, supporters of Andrew Jackson. Adams' generous policy towards Indians further served to not endear him to some, such as when the federal government sought to assert authority on behalf of the Cherokee, causing Georgia to take up arms. The final nail in the coffin of the Adams administration would turn out to be when President Adams signed the Tariff of 1828 into law, which intended to protect northern industry, while the South saw it as an economic blow. The "Tariff of Abominations," as it was called, was highly unpopular in the South, and virtually crippled the administration in its final year.
The campaign was brutal, bitter, and personal, with even Jackson's wife attacked, accused of bigamy. In the end, Adams lost handily: 178-83 in the electoral college. Adams, like his father, chose not to attend his successor's inauguration ceremony. In 1830, he would go on to be the first former president elected to Congress after serving as president.
The People's President -- The Era of Andrew Jackson
Election and Inauguration
The three week journey from Nashville, Tennessee, to Washington, DC, was filled with jubilation, as crowds swarmed to catch a glimpse of the new president-elect Andrew Jackson. The inauguration ceremonies of former presidents were all indoor affairs, invite only. On March 29, 1829, however, there was a sense that this new president was a man of the people. The ceremony was held on the East Portico of the U.S. Capitol, where 21,000 people eventually gathered to view the swearing-in.
The new president left through the west front of the capital and proceeded to the executive mansion for the reception on a white horse. By the time he arrived, the White House had already been invaded by supporters, as the festivities had been opened to the public. Supreme Court Justice Joseph Story noted, "I never saw such a mixture. The reign of King Mob seemed triumphant."
The new president was forced to sneak out of the White House before heading to Alexandria, Virginia. The crowd remained, however, until the liquor was moved to the front lawn. The White House was left a mess, including thousands of dollars in broken china.
Petticoat Affair and the Kitchen Cabinet
The Petticoat Affair is also known as the Eaton Affair. Happening in the U.S. between 1830-1831. It was a U.S. scandal involving President Andrew Jackson's cabinet and their wives. Even though this was a private matter, it still troubled several men in their political careers. The Petticoat affair involved Peggy Eaton who was accused of having an affair with a man by the name of John Eaton during the time she was married to purser John Timberlake. Daughter of William O Neal, Peggy remained close to politics her father owned the Washington D.C Boarding House for politicians where Peggy worked. Peggy frequented the boarding house which later gave spectators more discrepancies in Peggy's character as she looses popularity. Peggy husband died while on sea and many believed it was a suicide after being revealed to of his wife Peggy's affair with John Eaton who was a good friend of couple. Although Timberlake's death was said to be a result of pneumonia. Peggy married John Eaton less than a year after her husbands death. Many surrounding women felt like the marriage of Peggy and John Eaton was not the correct thing to do. The alleged affair controversy ultimately assisted many men in Andrew Jackson's cabinet to resign from their position, including John Eaton himself. People begin to judge Jackson on the his position on the marriage. Andrew Jackson recommended that John Eaton and Peggy should get married, Jackson views resulted on from his personal experience he had with his first wife.A group of women emerged claimed to be Anti-Peggy who was led by Floride Calhoun. The women who emerged proclaimed rights and guidelines that women have to follow after death of husband including that they mourn and wear black for a year following their death.
Nullification Crisis
One of the early crises faced by the Jackson administration was the issue of nullification. In 1828, Congress decided to raise an already high tariff on imports from Europe. It was meant to help the industrialized North compete with Europe, but the agricultural South detested it, as it traded heavily with Europe. The South called it the "Tariff of Abominations."
The concept of nullification, that states had the right to nullify any federal law which it deemed went against its interests, had first appeared in the Virginia and Kentucky Resolutions in 1798. In response to the tariff, South Carolina declared it null and void. Vice President John C. Calhoun agreed with this notion of states’ rights and encouraged South Carolina to take a stand on the tariff issue.
Up until that point, no one was sure where Jackson stood on the issue of states' rights. Then, in April, 1830, he announced that he opposed states rights in this instance. While President Jackson sympathized with the South's position on the tariff, he believed in a strong union with central power. As a result, a deep rivalry developed between Jackson and Calhoun. The rivalry can be epitomized in an incident at the Jefferson Day dinner, April 13, 1830, in which South Carolina Senator Robert Hayne made a toast to "The Union of the States, and the Sovereignty of the States." President Jackson added (and clearly directed towards the vice president), "Our federal Union: It must be preserved!" To this, Vice President Calhoun responded: "The Union: Next to our Liberty, the most dear!" In 1831, the first ever Democratic National Convention was held, and former Secretary of State Martin Van Buren (who was still playing a vital role in the President's "kitchen cabinet") was selected to replace Calhoun as the nominee for vice president in the 1832 election. The vice president resigned in December 1832 to run for the South Carolina U.S. Senate seat.
The South would not compromise on this lower tax, and South Carolina passed the Nullification Act which proclaimed that the state would no longer pay the "illegal" tariffs. South Carolina threatened to secede from the Union if the federal government tried to interfere.
President Jackson continued to oppose nullification, stating that "The Constitution... forms a government not a league... To say that any State may at pleasure secede from the Union is to say that the United States is not a nation." In 1832 he asked Congress to pass a "force bill," authorizing the use of military force to enforce the tariff law. The bill was held up in Congress until the great compromiser Henry Clay and the protectionists agreed to a Compromise Tariff bill. The Compromise Tariff contained a lower but still fairly high tariff. Both bills passed on March 1, 1833, and the president signed both.
In the face of the threat of military force, South Carolina quickly agreed to the lower compromise tariff and abolished the Nullification Act. The crisis was averted for another day.
Indian Policies
The lives of the Indians became even more troubled once a man who had been a friend, Andrew Jackson, became President of the United States. In 1830, Jackson signed the Indian Removal Act, this act removed any claims of the indigenous people to the land. This affected five tribes of the east—Cherokee, Creek, Chickasaw, Choctaw, and Seminole. The act would subsequently resettle them into a designated Indian Territory, which would be where Oklahoma is today. In spite of legal protests from tribal leaders, Jackson wanted them gone, even if he had to use military force in order to do it. Jackson decided that the Indians were a threat to national security. He also had a personal financial stake in some of the territory in question. With each treaty signed by the Native Americans, a white investor could purchase the ceded lands for themselves. In spite of this, the Cherokee, continued to pursue justice legally and actually was victorious in 1832 when the U.S. Supreme Court declared that the individual states had no jurisdiction within tribal lands. Jackson, argued that Indian removal was in the national interest, and ignored the ruling. The aftermath becomes known as the Trail of Tears. The Trail of Tears begins on October 8, 1832 and lasts for years. Indians are forced off of their land and migrate to the west.
Second Bank of the United States
The Second Bank of the United States began about 5 years after the First Bank of the United States fell. The Second Bank of the United States began in the same place as the first, Carpenters' Hall, Philadelphia. It had many branches through out the nation. Many of the same men from the First Bank ran the Second bank, when they refused to renew the charter of the First Bank. The main reason the Second Bank rose was because of the war of 1812. The U.S. suffered a horrible inflation and had trouble financing military operations. Like the first, bank many speculators believed the bank was corrupt. Second Bank ending up suffering from similar issues as the first bank and was ultimately disposed.
Gag Rule
The Gag Rule of 1836 is a rule that limits or forbids the raising, consideration or discussion of a particular topic by members of a legislative or decision-making body. The term originated in the mid-1830s, about 1836, when the U.S. House of Representatives barred discussion or referral to committee of antislavery petitions. The gag rule was supported by people involved in proslavery. The gag rule helped limit the progression of antislavery petitions. After antislavery petitions begin to emerge the democrats create initial gag orders to prevent the petitions.John Quincy Adams opposed the gag rule and said that limited and diregarded basic civil rights for free citizens. John Quincy Adams was member of the whig party with numerous pushed to eliminated the gag rule.
Panic of 1837
The Panic of 1837 was a financial crisis in the United States because of frequent actions of buying and selling housing properties.This all happened in New York City, on May 10, 1837, when every bank began to accept payment in Specie(Gold and Silver). This also happened due to when President Andrew Jacksons came up with the Specie Circular and when he refused to renew the charter of the Second Bank.
Reform and American Society
The Second Great Awakening
The Second Great Awakening was a religious movement during the early 19th century in the United States. Which showed Arminian Theology, by which every person could be saved through revivals.The Awakening grew largely in opposition to deism related to the French Revolution. The Second Awakening grew after a revival in Uttica New York which was hosted by Charles Grandison Finney. Finney believed spoke to congregations in America stating that people were " moral free agents." Charles spoke about Calvinist beliefs and that everyone had a defined destiny. Awakenings were described as spiritual and religious revivals where people will congregate and confess to their sins. By 1831 church membership had grew by 100,000 solely as a result to awakenings that were carried out by preachers like Charles Finney and Theodore Weld.
Throughout the late 1700s and 1800s, alcoholism became an increasing problem, and as a result, temperance groups began forming in several states to reduce the consumption of alcohol. Although the temperance movement began with the intent of limiting use, some temperance leaders such as Connecticut minister Lyman Beecher began urging fellow citizens to abstain from drinking in 1825. In 1826, the American Temperance Society formed in a resurgence of religion and morality. By the late 1830s, the American Temperance Society had membership of 1,500,000, and many Protestant churches began to preach temperance.
Public Education
In the New England states, public education was common, even though it was class-based with the working class receiving minimum benefits. Schools taught religious values and also taught Calvinist philosophies of discipline, including corporal punishment and public humiliation.In 1833 Oberlin college had in attendance 29 men and 15 women. Oberlin college came to be known the first college that allowed women attend. Within five years, thirty-two boarding schools enrolled Indian students. They substituted English for American Indian languages and taught Agriculture alongside the Christian Gospel. Horace Mann was considered “The Father of American Education.” He wanted to develop a school that would help to get rid of the differences between boys and girls when it came to education. He also felt that this could help keep the crime rate down. He was the first Secretary for the Board of Education in Massachusetts in 1837-1848. He also helped to established the first school for the education of teachers in America in 1839.
Asylum Movement
The Asylum Movement was a social conscience that was increased in the early 19th century the helped raise the awareness of mental illness and its treatment.] The first asylum in America was in 1817 near Frankfort, PA. Later in 1817 another asylum emerged in Hartford, Connecticut. The asylums grew popularity and influenced other states to create asylums similar, like Massachusetts, Massachusetts State Lunatic Hospital in 1833. Prior to 1840 only wealthy people were permitted to the asylums. Many people that were mentally ill who did not have finances, were permitted to jails and almshouses.
Abolitionism is the movement for which the purpose is to abolish slavery. While many believed in the injustices that those in the south believed, there were also those who opposed the heinous acts they did to African Americans. There were many people involved in helping slaves to escape to freedom. The movement was expanding. As it got bigger and bigger the hostilities between the north and the south grew as well. The Underground Railroad stemmed from the hearts and minds of these abolitionist freedom fighters. Harriet Tubman and Frederick Douglass were two popular African Americans who were a part of the abolitionist movement.
- A People and A Nation, Eighth Edition
- A People and A Nation, Eighth Edition
- A People and A Nation, Eighth Edition | http://en.wikibooks.org/wiki/US_History/War,_Nationalism,_and_Division | 13 |
42 | There are two main types of taxes (1)
direct tax and (2) indirect tax.
Explanation of Direct Tax:
A tax is said to be direct tax
impact and Incidence of a tax are on one and same person, i.e., when a
person on whom tax is levied is the same who finally bears the! burden of tax.
For Instance, income tax is a direct
tax because impact and incidence falls on the same person.
If impact of tax falls on one persons and incidence on the another,
the tax is called indirect.
For example, tax on saleable articles is
usually an indirect tax because it can be shifted on to the consumers.
Merits of Direct Tax:
(i) Direct taxes afford a greater degree of progression. They are, therefore,
(ii) They entail less expenses on collection and as such are economical.
(iii) They satisfy canons of
certainty, elasticity, productivity and simplicity.
(iv) Another advantage of direct taxes is
that they create civic consciousness in people. When a person has to bear burden
of tax, he takes active interest in affairs of state.
Demerits of Direct
(i) It is easy to evade a direct tax than an indirect tax. Taxpayer is seldom
happy when he pays tax. It pinches him that his hard-earned money is being taken
by government. So he often submits false statements of his income and thus tries
to evade tax. Direct tax is in fact a tax of honesty.
(ii) Direct tax is very inconvenience because taxpayer has to prepare lengthy
statements of his income and expenditure. He has to keep a record of his income
up-to-date throughout the year. It is very laborious for taxpayer to prepare and
keep these records.
(iii) Direct tax is to be paid in
lump some every year while income which a person earns is received in small
amounts. It often becomes difficult by taxpayers to pay large amounts in one
Indirect taxes are those taxes which are paid in the first instance by one
person and then are shifted on to some other persons. The impact is one person
but the incidence is on the other.
Merits of Indirect Tax:
(i) It is not possible to evade indirect tax. The only way to avoid this tax
is not to buy taxed commodities.
(ii) They are more convenient because they
are wrapped in prices. Consumer
often does not know that he is paying tax.
(iii) Another advantage of tax is that every member of society contributes
something towards revenue of state.
(iv) Indirect tax is also elastic to a certain extent. State can increase its
revenue within limits by increasing rates of taxes.
(v) If state wishes to discourage consumption of intoxicants and harmful
drugs, it can raise their prices by taxing them. This is a great social
advantage which a community can achieve from tax.
Demerits of Indirect Tax:
(i) A very serious objection leveled against indirect taxation is that it is
regressive in character. It is inequitable. Burden of tax falls more on poor
people than on rich.
(ii) Indirect tax is also uneconomical. State has to spend large amounts of
money on collection of taxes.
(iii) Revenue from indirect tax is uncertain. State cannot correctly estimate as
to how much money will it receive from this tax.
(iv) As lax is wrapped up in prices; therefore, it does not create civic
(v) If goods produced by manufacturers are taxed at higher rates, it hampers
trade and industry and causes widespread unemployment in the country.
After discussing merits and demerits of two types of taxes, we come to
conclusion that for reducing inequality of income and raising sufficient funds
for state, both these taxes are essential, A country should not place exclusive
reliance on any one type, but should employ both these forms of taxation.
agree here with Galdston when he says:
"Direct and Indirect taxes
are like two equally fair sisters to whom as Chancellor of Exchequer, he had to
pay equal addresses".
In recent times, however, there has
been a slight change in utilization of both these types of taxes. Every state,
in order to reduce inequality of income, is trying to raise major portion of its
income from direct taxes. | http://www.economicsconcepts.com/direct_tax_and_indirect_tax.htm | 13 |
37 | Money Connection—Unit 3
This lesson focuses on the impact of too much money or too little money flowing in the economy in terms of jobs, prices, and production of goods and services. A simulation is used to demonstrate the impact of inflation on the economy.
Money Connection Video
The Money Connection is a lively, two-part video (approximately 17 minutes) designed to introduce fourth through sixth grade audiences to the Federal Reserve System. The fast-paced, news show format combines historical photographs and live-action footage with interviews and animation sequences for a close up look at the history and important responsibilities and functions of the Federal Reserve.
The "What is a dollar worth?" calculator allows you to compare prices for goods or services from different periods of time. For example, you can compare the price you paid for a dozen eggs in 1972 with the price you paid last week.
Time Value of Money Online Learning Module
This online learning module helps students learn about the time value of money, opportunity costs, interest and inflation. The module also focuses on mathematical components and calculations of the related time value formulas.
Consumer Price Index Video
This Drawing Board video explains the Median Consumer Price Index (CPI) and how it is used to gauge inflation.
Other Inflation Teaching Ideas
Find out what methods other educators in the Southeast have used to teach concepts related to inflation.
The Fed Today—Lesson Four: The Fed's Role in Making and Setting Monetary Policy
This lesson focuses on price stability and inflation. Students discuss how to define inflation and analyze the relationship between the money supply and the price level using the Fisher Equation. Students then examine the harmful effects of inflation on the economy. Finally, small groups of students determine how business and consumer behavior changed during the 1970s when inflation had a negative impact on the nation's economy.
A Lesson to Accompany "Benjamin Franklin and the Birth of a Paper Money Economy"
In this lesson, students learn about the role of money in the colonial economy by participating in a trading activity in which they observe the effects of too little money on trade within a colony. In the final activity, students learn how too much money can lead to inflation. Related essay
Advanced High School to College
The Economy: Crisis and Response—The Road Ahead
As the economy moves toward recovery, the Fed will remain active in its response, including unwinding certain policies as conditions warrant. This website examines the economic outlook, why inflation is a topic of focus, and the changes in regulation needed to strengthen the financial markets.
The Inflation Project
Tracking inflation and its effects is a vital component of the Federal Reserve's monetary policy. The Inflation Project regularly compiles links to data releases, reports, research, and international inflation updates.
The Summary of Commentary on Current Economic Conditions, commonly known as the Beige Book, gathers anecdotal information on current economic conditions in each Federal Reserve District through reports from Bank and Branch directors and interviews with key business contacts, economists, market experts, and other sources. The Beige Book summarizes this information by District and sector. | http://www.frbatlanta.org/edresources/classroomeconomist/inflation_resources.cfm | 13 |
15 | Traditional methods of food drying is to spread the foodstuffs to place the foodstuffs in the sun in the open air. This method, called sun drying, is effective for small amounts of food. The area needed for sun drying expands with food quantity and since the food is placed in the open air, it is easily contaminated. Therefore, one major reason why sun drying is not easily performed with larger quantities of food is that the monitoring and overview becomes increasingly more difficult with increasing food quantities.
In contrast to sun drying, where the meat is exposed directly to the sun, the solar drying method uses indirect solar radiation. The principle of the solar drying technique is to collect solar energy by heating-up the air volume in solar collectors and conduct the hot air from the collector to an attached enclosure, the meat drying chamber. Here the products to be dried are laid out.
In this closed system, consisting of a solar collector and a meat drying chamber, without direct exposure of the meat to the environment, meat drying is more hygienic as there is no secondary contamination of the products through rain, dust, insects, rodents or birds. The products are dried by hot air only. There is no direct impact of solar radiation (sunshine) on the product. The solar energy produces hot air in the solar collectors. Increasing the temperature in a given volume of air decreases the relative air humidity and increases the water absorption capacity of the air. A steady stream of hot air into the drying chamber circulating through and over the meat pieces results in continuous and efficient dehydration.
The solar dryer is a relatively simple concept. The basic principles employed in a solar dryer are:
- Converting light to heat: Any black on the inside of a solar dryer will improve the effectiveness of turning light into heat.
- Trapping heat: Isolating the air inside the dryer from the air outside the dryer makes an important difference. Using a clear solid, like a plastic bag or a glass cover, will allow light to enter, but once the light is absorbed and converted to heat, a plastic bag or glass cover will trap the heat inside. This makes it possible to reach similar temperatures on cold and windy days as on hot days.
- Moving the heat to the food. Both the natural convection dryer and the forced convection dryer use the convection of the heated air to move the heat to the food.
There are a variety of solar dryer designs. Principally, solar dryers can be categorized into three groups: a) natural convection dryers, which are solar dryers that use the natural vertical convection that occurs when air is heated and b) forced convection dryers, in which the convection is forced over the food through the use of a fan and c) tunnel dryers.
While several different designs of the solar dryers exist, the basic components of a solar dryer are illustrated in Figure 1. In the case of a forced convection dryer, an additional component would be the fan.
The structure of a tunnel dryer is relatively simple. The basic design components of a tunnel dryer are the following:
- A semi circular shaped solar tunnel in the form of a poly house framed structure with UV stabilized polythene sheet
- The structure is, in contrast to the other dryer designs, large enough for a person to enter
The design of a tunnel dryer is illustrated in Figure 2. In addition, the technology teaser image at the top of this description is an image of the inside of a tunnel dryer.
Natural Convection Dryer Large scale design
Generally, natural convection dryers are sized appropriately for on-farm use. One design that has undergone considerable development by the Asian Institute of Technology in Bangkok, Thailand is shown in Figure 3. This natural covenction dryer is a large scale structure: the collector is 4.5 meters long and 7 meters wide and the drying bin is 1 meter long and 7 meters wide. The structure consists of three main components: a solar collector, a drying bin and a solar chimney. The drying bin in this design is made of bamboo matting. In addition to the collector, air inside the solar chimney is heated which also increases the thermal draught through the dryer. The solar chimney is covered with black plastic sheet in order to increase the thermal absorption. A disadvantage of the dryer is its high structural profile which poses stability problems in windy conditions, and the need to replace the plastic sheet every 1-2 years.
Figure 4 shows a smaller design for a natural convection dryer. The capacity of this dryer is ten times smaller than the capacity for food drying in the larger design. However, the design is simple to build and is less susceptible to stability problems.
Natural Convection dryer small scale design
These solar food dryers are basically wooden boxes with vents at the top and bottom. Food is placed on screened frames which slide into the boxes. A properly sized solar air heater with south-facing plastic glazing and a black metal absorber is connected to the bottom of the boxes. Air enters the bottom of the solar air heater and is heated by the black metal absorber. The warm air rises up past the food and out through the vents at the top (see Figure 5). While operating, these dryers produce temperatures of 130–180° F (54–82° C), which is a desirable range for most food drying and for pasteurization. With these dryers, it’s possible to dry food in one day, even when it is partly cloudy, hazy, and very humid. Inside, there are thirteen shelves that will hold 35 to 40 medium sized apples or peaches cut into thin slices.
In the case of forced convection dryers, the structure can be relatively similar. However, the forced convection dryer requires a power source for the fans to provide the air flow. The forced convection dryer doesn't require an incline for the air flow however, the collector can be placed horizontallly with the fan at one end and the drying bin at the other end. In addition, the forced convection dryer is less dependent on solar energy as it provides the air flow itself; this allows the design to work in weather conditions in which the natural convection dryer doesn't work. As inadequate ventilation is a primary cause of loss of food in solar food dryers, and is made worse by intermittent heating, it is essential to realize proper ventilation. Adding a forced convection flow, for instance provided through a PV- solar cell connected to a fan, will prevent the loss of food.
Drying is an important step in the food production process. The main argument for food drying is to preserve the food for longer periods of time. However, it is important to note that the process is not just concerned with the removal of moisture content from the food. Additional quality factors are influenced by the selection of drying conditions and equipment:
- Moisture Content. It is essential that the foodstuff after drying is at a moisture content suitable for storage. The desired moisture content will depend on the type of food, duration of storage and the storage conditions available. The drying operation is also essential in minimizing the range of moisture levels in the batch of food as portions of under-dried food can lead to deterioration of the entire batch.
- Nutritive value. Food constituents can be adversely affected when excessive temperatures are reached.
- Mould growth. The rate of development of micro-organisms is dependent on the food moisture content, temperature and the degree of physical damage to the food.
- Appearance and smell of the food. For example, the colour of milled rice can be adversely affected if the paddy is dried with direct heated dryers with poorly maintained or operated burners or furnaces.
Therefore, it is essential to not only monitor the moisture content of the foodstuffs, but to also monitor temperature, mould growth, appearance and smell of food, air flow, etc. Whether a natural convection dryer, a forced convection dryer or a tunnel dryer is appropriate depends on the amount of food, the climate and the demands placed on the end-product (how long does it need to be stored, in what quantities, etc.). A typical pattern of several of these factors is shown in Figure 6.
In addition, an important feature of solar drying devices is the size of the solar collectors. Depending on the quantity of goods to be dried, collectors must have the capacity to provide sufficient quantities of hot air to the drying chamber. Collectors which are too small in proportion to the amount of food to be dried will result in failed attempts and spoiled food.
According to the FAO (no date), the most common drying method of grain in tropical developing countries is sun drying. The process of sun drying starts when the crop is standing in the field prior to harvest; maize may be left on the standing plant for several weeks after attaining maturity. However, this may render the grain subject to insect infestation and mould growth. In addition, it prevents the land being prepared for the next crop and is vulnerable to theft and damage from animals.
A more controlled practice is to bring the foodstuffs into a structure which is specifically designed for food drying. This removes the issue of bacterial contamination, theft and insect infestation. Modern variations are to dry food in special enclosed drying racks or cabinets and expose the food to a flow of dry air heated by electricity, propane or solar radiation.
Although it is difficult to establish the current status of the technology in terms of market penetration as data on this technology is insufficient, some general remarks can be made about the market potential.
There seem to be no major design barriers to a solar dryer: the design is easy to build with a minimum of materials required. This is especially true for the natural convection dryer, which doesn't require any machinery or energy source (next to the solar energy source). In contrast, the forced convection flow, the electricity heated design and the propane fuelled dryers all require some form of machinery and require an external heat source (in the form of electricity or propane). This complicates their designs and makes their operational costs more expensive. However, these designs possibly do have lower food loss rates due to more constant air flow.
Related to the previous remark, the easy design cuts costs. The design can be made primarily from materials found in the local surroundings. For instance the frame of the structure can be constructed from wood, bamboo or any other natural product that is strong enough. This characteristic enhances the market potential of this product.
The technology provides several socio-economic benefits. As the FAO (2010) notes, one of the main issues facing developing countries today is the issue of food security. The solar food dryer can improve food security through allowing the longer storage of food after drying compared to food that hasn't been dried.
The solar dryer can save fuel and electricity when it replaces dryer variations that require an external energy source in the form of electricity or fossil fuel. In addition solar food dryers cut drying times in comparison to sun drying. While fossil fuel or electrically powered dryers might provide certain benefits (more consistent air flow and higher temperatures), the financial barriers that these technologies provide might be too high for marginal farmers. For instance, electricity might be not available or too expensive and fossil fuel powered drying might pose large initial and running costs.
Fruits, vegetables and meat dried in a solar dryer are better in quality and hygiene compared to fruits, vegetables and meat dried in sun drying conditions. As mentioned, due to the closed system design, contamination of food is prevented or minimized. In addition, the food is not vulnerable to rain and dust, compared to the open system design of sun drying.
In rural areas where farmers grow fruits and vegetables without proper food drying facilities, the farmers need to sell the food in the market shortly after harvesting. When food production is high, the farmers have to sell the food at low price to prevent the food from losing value through decomposition. Therefore, the solar food dryer might be able to prevent the financial losses farmers in these situations face. Dried food can be stored longer and retain quality longer. Moreover, dried fruits and vegetables might be sold as differentiated products which possibly enhances their market value. For example, dried meat can be processed into a variety of different products.
Drying food reduces its volume. Therefore, in combination to longer storage times, the food is also more easily transported after drying which potentially opens up additional markets to the producer of the food.
While there is insufficient data at the moment to elaborate fully on the financial requirements and costs of this technology, certain general remarks can be made.
For natural convection dryers, the financial requirements are low. The structure is made from components that are mostly easily available (wood, bamboo, other strong construction materials). However, the major cost components are likely to be the glass sheets required to trap the heat, and the plastic sheets need to be available. Operational costs of the natural convection technology are limited to labour costs. Forced convection dryers have higer initial costs and higher operational costs, as the fan needs to be purchased and operated.
As mentioned, dried food products might yield a higher price on the market as it can be sold out-of-season (the fresh food version might no longer be on the market in a particular season, which might increase the price of the dried version of the food.
FAO, 2010. “Climate-Smart” Agriculture - Policies, Practices and Financing for Food Security, Adaptation and Mitigation. Food and Agriculture Organization of the United Nations 2010. Document can be found at: http://www.fao.org
FAO, no date. Information retrieved from the following websites: http://www.fao.org/docrep/t0395e/T0395E04.htm , http://www.fao.org/docrep/x0209e/x0209e06.htm and http://www.fao.org/docrep/t1838e/T1838E0v.htm | http://climatetechwiki.org/print/technology/jiqweb-edf | 13 |
19 | "The American Civil Rights Movement (1955–1968) refers to the reform movements in the United State(...TRUNCATED) | http://www.reference.com/browse/American+Civil+Rights+Movement+(1955%E2%80%931968) | 13 |
15 | "The labor movement in the United States grew out of the need to protect the common interest of work(...TRUNCATED) | http://www.history.com/topics/print/labor | 13 |
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