Lec 16 | MIT 5.111 Principles of Chemical Science, Fall 2005

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Lec 16 | MIT 5.111 Principles of Chemical Science, Fall 2005

The following content is provided by MIT OpenCourseWare under a Creative Commons license Additional information about our license and MIT OpenCourseWare in general is available at ocw.mit.edu Last time, we were talking about this valence bond model for describing the bonding In particular, the bonding between atoms in a polyatomic molecule And we saw that the key to this description was allowing the wave functions, the individual wave functions on an atom to constructively and destructively interfere themselves to form some hybrid wave functions, to form some hybrid orbitals And then it is those hybrid wave functions that overlap with the wave functions of another atom to form a chemical bond And, in particular, what we treated last time were these sp^3 hybrid wave functions that were centered on carbon, that were centered on nitrogen, that were centered on oxygen And we saw that these sp^3 wave functions were this linear combination, or this destructive and constructive interference between the s wave function and the three 2p wave functions — To form these sp^3 wave functions and correspondingly these sp^3 states And, as I said, we saw that on carbon, we saw that on nitrogen, we saw that on oxygen And those wave functions end up being pointed to the corner or to the vertex of a tetrahedron where the atom was at the center of that tetrahedron In the case of methane then, if you bond a hydrogen to each one of those sp3 hybrid wave functions, what you get is a tetrahedral geometry around the carbon If you had a nitrogen with those sp63 wave functions around it, and you bonded to three hydrogens, then you got a trigonal pyramid as the geometry of the ammonia molecule with those two lone pairs sticking out there at another vertex of a tetrahedron But remember we talked about the shape of the molecule as being described by the positions of the atoms and not the positions of the electrons And we talked about water Water, sp^3 hybridized We add two hydrogens to it We form two bonds that are planar bent And then we have two lone pair electrons sticking out of the oxygen Those are going to play a big role in some of the bonding we’re going to look at, at the end of the lecture today We have got to move on And we have got to talk about another kind of hybridization, which we started to talk about last time, which is this sp^2 hybridization And we talked about it on boron We saw that the sp^2 wave functions end up being in a plane which, in the case of boron, if we then bonded hydrogens to those sp^2 wave functions, we got a planer molecule for boron H three But carbon can also undergo this sp^2 hybridization And so let’s take a look at that now In the case of carbon, we have to do this electron promotion that we talked about also in the case of the sp^3 hybridization And then we let now one of the 2s wave functions and two of the 2p wave functions hybridize, constructively and destructively interfere And the result is three sp^2 wave functions or three sp^2 states with one electron in each one of them And then one of those p orbitals or those p wave functions on the carbon is untouched That is just the atomic wave function, the atomic orbital on that carbon And if we look at the picture of all of those wave functions here it is This is the 2s on the carbon, 2pz, 2px, 2py And what we did is let these three, for example, constructively and destructively interfere to form

these three sp^2 hybrid orbitals or hybrid wave functions And the result is that they look like this The result is they all have a large positive lobe on them due to the constructive interference, and they all have a small negative lobe here And then all of the rest of the pictures that we are going to draw, we are not going to draw that small negative lobe because it just makes it hard to draw But the bottom line is that these three lobes lie in a plane And then, of course, we still had that 2py atomic wave function centered on the carbon And that is unperturbed Now what I am going to do is I am going to put all of these three wave functions on the same plot, since they all have the same origin So that is what I am doing right there There it is for the carbon, with the three positive lobes of that sp^2 wave function all in the same plane Again, I didn’t draw the little part of the negative wave function in this picture But now, what we also have is that 2py wave function, the 2p wave function on the carbon that hasn’t hybridized Oh, I’m sorry That hasn’t hybridized, right? And it is sticking out of the plane of the board, right? That’s the 2p orbital that you are used to seeing on the carbon And it is perpendicular here to the plane in which the sp^2 wave functions are sitting Now, what we are going to do is I am going to take this sp^2 hybridized carbon, where the positive lobes of these sp^2 wave functions are all 120 degrees away from each other And where you would say these wave functions had a trigonal planar configuration I am going to take this sp^2 wave function, and I am just going to rotate it so that this lobe here is parallel to the floor I am going to do that for convenience And you are going to see why in a moment That is what happens here on the next slide I just rotated this by 90 degrees, in particular, so I could put the z-axis here along a bond I am going to form That is the top view Now, let’s look at what this looks like from the side From the side, what it would like is something like that The carbon is right here at the center Then the positive lobe, this positive part of the wave function, that is what this is, here This 2py wave function, well, here it is It is perpendicular to this plane that you are looking down on up here It is perpendicular to this plane That is that 2py wave function Positive part of the p wave function, negative part of the p wave function And then this part of the wave function, well, this is just a projection of these two big positive parts of the wave function This just projects this way and out that way That is what it looks like from the side Now what I am going to do, is I am going to bring in another sp^2 hybridized carbon up here I am going to bring it in It is going to look just like that Here it comes And when I do that, what is going to happen right here is that I am going to allow the 2sp^2 wave function from this carbon to overlap with the 2sp^2 wave function from this carbon and I am going to form a bond And that is going to be a sigma bond, sigma because it is going to be cylindrically symmetric around this carbon-carbon bond axis And it is a sigma bond formed by the carbon 2sp^2 hybrid wave function and the other carbon 2sp^2 hybrid wave function I have formed a bond here And now, what I am going to do is bring this carbon sp^2 hybridized wave function or carbon in again But I am going to bring it in and we are going to watch this

view We are going to watch it from the side This time, what I want you to see is what is going to happen, here, to the 2py wave function Here it goes We are going to bring it in And then this 2sp^2 is going to form a bond here between this carbon, but now what happens is that those 2py wave functions overlap They constructively or destructively interfere If you want to watch it again, here it comes in, we are going to make this sigma bond, but now these two lobes are going to interfere and these two lobes are going to interfere And this is going to be constructive interference there because they both have a positive sign or negative sign And so we are going to have wave function up here and wave function down there We formed another bond right here The bond that we formed here is going to be called the pi bond It is pi because it is not cylindrically symmetric around this carbon-carbon axis There is wave function or electron density if you square it up here and wave function or electron density if you square it down here But right here, along the plane, there is a node in that pi wave function So this is a pi wave function made out of the atomic wave functions on carbon The atomic wave functions, the ones that haven’t participated in this hybridization It is made out of carbon 2py and carbon 2py What I have got here is a double bond I have two bonds between the two carbons I have got a sigma bond and I have got a pi bond That’s great Now let’s bring in some hydrogen I just did And when I brought in those hydrogens, well, you can recognize this as ethylene The hydrogens form a sigma bond between the carbon 2sp^2 hybrid wave function and the hydrogen 1s wave function That is what forms this sigma bond It is sigma because it is symmetric around that carbon-hydrogen bond access And the molecule that we have here is ethylene Now, let’s look at that again, because this is really very important Here I show you just those two 2p^2 hybridized carbons forming that sigma bond And this just represents, here, the energy levels as I bring them in In this case we have two electrons in this sp^2 state and we have one electron in each one of the 2py states And so this represents this sigma bond here And then we made a pi bond And we will watch it now from the top We made a pi bond We let these two 2py wave functions overlap, constructively interfere to form a pi bond, which is the carbon 2py, carbon 2py Clue here, every double bond has two bonds That’s why it is double But every double bond is made up of one sigma bond And the sigma bond is always the overlap between two 2sp^2 hybrid wave functions And the second bond that always makes up a double bond is a pi bond The pi bond is always the overlap of two atomic wave functions In the case here of carbon it is two 2p wave functions that have overlapped That is what a double bond always is It always is so whether it’s a carbon double bond or a nitrogen double bond or an oxygen double bond It is always one sigma, one pi And there are the hydrogens And, as we said, those hydrogens there, that carbon-hydrogen bond is this overlap between a carbon 2sp62 wave function and that hydrogen 1s wave function

And now, what is the geometry of ethylene? Well, the geometry here of ethylene is that the hydrogen-carbon-hydrogen bonds are 120 degrees That is 120 degrees because that is the result of the hybridization, that 2sp^2 hybridization of the wave functions around the carbon This bond here is 120 degrees, again, because of the 2sp^2 hybridization around that carbon So the geometry of this molecule is planar All of these atoms are in a plane Those six atoms are in a plane and the bond angles here are all 120 degrees Now, if you see a carbon that has a double bond If you see a nitrogen that has a double bond If you see an oxygen that has a double bond That is always a clue that that carbon, that nitrogen, that oxygen has a hybridization of 2sp^2 Double bonds have this hybridization always If you are asked to tell what the hybridization is around some atom, it has a double bond to it, it is a 2sp^2 hybrid Now, what I want to do is I want to take this 2sp^2 hybrid and build a larger molecule I am going to take this carbon two, take the two carbons here that are bonded via this 2sp^2 hydrogen So here are two of them And here are another two And they are kind of strategically placed for what it is I want to do And, of course, this is the sigma bond between the two carbons Here is the carbon 2sp^2 sigma bond Now, what I am going to do is bring in another carbon that is sp^2 hybridized Here it comes And, again, it is strategically oriented so that right here I have now formed another sigma bond between the carbon 2sp^2 wave function and the other carbon 2sp^2 wave function The same thing right here I just form two other sigma bonds And now, I am going to bring in a sixth carbon, sp^2 hybridized And it is going to come in from this side Again, it is strategically oriented I just formed, here, another sigma bond between these two carbons and another sigma bond between these two carbons Hey, look at this It is beginning to look a lot like benzene [LAUGHTER] That is my favorite part [APPLAUSE] Here come the hydrogens This is going to be benzene So what did I do here? I made some sigma bonds I made six sigma bonds between the carbon 2sp^2 wave functions and the hydrogen 1s wave functions Now I’ve got all of my atoms there and almost all of my bonds However, we have got to do something here about these 2p atomic wave functions that are centered on the carbon We are not done yet What is going to happen to them? Well, they are going to overlap, constructively and destructively interfere And to see that, let’s take this benzene molecule and rotate it 90 degrees so that we are going to look at it from the side-on view

instead of the top view So there it is Here are my carbon-carbon sigma bonds, the 2sp^2-2sp^2 bonds Here is my sigma bond between the hydrogen and the carbon 2sp^2 wave function And now I am going to let the 2p, the atomic wave functions, not the hybrid wave function on the carbon, the atomic wave functions on the carbon, I am going to let them constructively and destructively interfere And here it goes Well, they are going to overlap And I’ve got something that looks like a pi bond here I have wave function above the plane of these atoms, and I have wave function below the plane of these atoms It is a pi bond that is formed by the overlap of the 2p wave functions, the atomic wave functions on carbon It is pi because it is not symmetric around, now, the bond axis There is density up here, density up there, but not in the plane Let’s look at it again from the top view What did I do? Well, I let these 2p wave functions here overlap Let’s look at that a little more carefully What exactly did I do here? Well, what I did is, for example, I let the 2p wave functions on these two carbons overlap to form a pi bond I let the 2p wave functions on these two carbons overlap to form a pi bond And I let these two 2p wave functions overlap to form a pi bond Well, that is very nice, but I could also have let the 2p wave functions on these two carbons overlap or these two carbons In other words, I could have made a pi bond between these two carbons or these two carbons or these two carbons So which one do I choose? Well, in recitation the other day, you should have looked at the Lewis structure of molecular benzene or benzene And what you should have seen is that you would be able to write several different Lewis structures, all which have the same set of formal charges And that you wouldn’t be able to decide which structure you should have based on the formal charges Rather, what you had was a resonance structure And that is exactly what you have Instead of these six extra electrons, which are centered on the carbon, those 2p electrons, there is one here, one there, one there, one there, one there, one there Instead of each one of those electrons being shared between just one of the adjacent carbons, those six extra electrons are actually delocalized around all of the carbons And so what you are going to form here is not a clear double bond between this carbon and this one and this one Instead, what you are going to form is kind of a half of a pi bond That is, you are going to let those six electrons be equally distributed, so to speak, around all of the six carbons And so this pi bond here isn’t quite a full pi bond It is kind of half of a pi bond Because this carbon is sharing its 2p electron with this carbon and with this carbon, and vice versa all the way around And so we have this resonance structure I drew this as kind of a fuzzy green line there We have these six pi electrons that are delocalized amongst the six atoms of this carbon ring So these double bonds here are really a bond and a half

This bond is more than a single bond in terms of its bond strength and in terms of its distance It is closer than a single bond, but it isn’t as strong as a double bond, nor is it as short as a double bond It is somewhere in between That is the structure here of benzene So that takes care of sp^2 hybridization Now, we’ve got one other kind of motif and that is called sp hybridization And we are going to use carbon again as the example of this sp hybridization Again, since we are starting with carbon here, we are going to have to undergo this electron promotion process We are going to take an s electron Are there some questions here that I can help you with? No OK We are going to take that s electron and promote it to the 2p state And then we are going to do a hybridization, but this time, what we are going to do is let the 2s atomic wave function hybridize with one of the 2p wave functions And the result, then, is that we are going to have a new wave function that we are going to call sp, and there is only going to be two of them, because we only let one of the 2s and one of the 2p’s constructively or destructively interfere So we are going to get two sp states or two new sp wave functions Each one has got an electron in it Each state has got an electron in it And then we’ve got left over two atomic states centered on the carbon, the py and the px Each one has an electron in it Yes? Well, by convention here yes The p state we are going to hybridize is going to be 2pz, and that is because that is the wave function I am going to make a bond to And I want that along the internuclear axis In real life you cannot tell what is x, y or z, but by convention we are always going to put the z-axis along the bond axis And I will say a little more about labeling py and pz and an example that I am going to do in a few minutes, so I hope that will clear things up In the picture form, here are our three atomic wave functions again And I am going to let these two constructively and destructively interfere And the result is, then, two new sp wave functions Now, given that I am letting only two wave functions constructively and destructively interfere, it is a little bit easier to see how I get these shapes Here it goes This 2s wave function, remember the 2s wave function always has one sign? Say it has a plus sign, it never crosses the axis There are no nodes, right? No radial nodes When you have a node, that is when the wave function changes sign I am going to put that 2s wave function in the same place in space as this 2pz wave function When I do that, since this is a wave, it is going to constructively and destructively interfere Up here, where I am constructively interfering this positive wave function with the positive part of the 2pz wave function, I am going to get a lot of positive wave function That is where this lobe comes from But down here, where this is positive and this is negative, that is going to be destructive interference And because this negative part of the 2pz lobe is actually larger than the 2s that is positive, well, I am going to have a little bit of leftover of a negative wave function Here, it is easier to see how

you get this shape by the interference of that wave function with that wave function And then, correspondingly, I am going to let this wave function and that wave function destructively interfere If this is still positive, positive minus a positive is going to give me a little bit of a wave function and it is going to be negative And then positive minus a negative, that is going to give me a positive Here is my big positive part of the wave function That is a little bit easier to see, now, than in the sp^3 case, where it is not so easy to see These are now my two new 2p wave functions And the atomic wave functions here, I haven’t done anything to them Now, I am going to put these wave functions all on one plot They all have the same origin It is the carbon right in the center I am going to put them all on one plot Here they are And, what I did is that I rotated the z-axis It was going up and down here The z-axis in this picture is coming this way It is parallel to the floor Again, strategically placed for the next bond formation But here, you can see the 2px wave function, the atomic wave function, untouched And perpendicular to it, you can see the 2py wave function, untouched Now I am going to take another sp carbon wave function and bring it in, and I am going to let the sp wave functions on the two carbons overlap, so that I form a sigma bond Sigma formed by the carbon 2sp, carbon 2sp That’s my sigma bond there But now, you know what is going to happen? We are going to let the atomic wave functions on the two carbons constructively and destructively interfere Oh, I am going to bring in hydrogens first Sorry We brought in the hydrogen and formed this sigma bond between the carbon 2sp wave function and the hydrogen 1s wave function And we’ve got acetylene Except now we’ve got to let the 2p atomic wave functions on each carbon interfere Except I wanted to point out this geometry [LAUGHTER] I got this all wrong This is 180 degrees because the sp wave functions lie in a line The hydrogen-carbon-carbon-hydrogen here, that bond angle is 180 degrees We have a linear molecule And now, we are going to let the 2p wave functions interfere When we did that, we are going to form a pi bond The interference of this 2py and this 2py is going to be a pi bond It is pi because it is not cylindrically symmetric around this carbon-carbon bond axis There is electron density above the plane of the slide and below the plane of the slide We’ve got a pi bond here And then, finally, we are going to let these two atomic wave functions constructively and destructively interfere, the 2px Again, we are going to form a pi bond It is pi because it is not cylindrically symmetric around the bond axis There is electron density up here and electron density up there What we have here is a triple bond We have, between the two carbons, one sigma bond, one pi bond and another pi bond The two pi bonds are perpendicular to each other That is important So a triple bond is always composed of one sigma bond and two pi bonds That is the case, whether you’re looking at a triple bond on carbon or nitrogen or anything else, well, almost anything else that forms a triple bond But, for your intents and purposes, carbon and nitrogen are going to form a triple bond That is important here Those are our hybridization schemes that we are going to look at

And it is going to allow us to describe the bonding in lots and lots of molecules And one of the molecules that I want to describe the bonding of is this molecule It is methyl nitrate This is going to help you out on the homework here Suppose you are asked to describe the bonding in methyl nitrate, and you are given this structure Well, the first thing you have to do is write down a skeletal structure, and to actually, in your mind, get down what the Lewis structure is for methyl nitrate A couple of days ago I told you that when you see a CH three species like that, it is a methyl group That is always terminal That is a carbon with three hydrogens bond to it And so that is what we are going to do We are going to make this carbon there with the three hydrogens bound to it And then, if you have a long molecule like this, one place to start is to then just bind this atom to the next atom So I did that I put the carbon bound to the oxygen And then following that rule, I took the oxygen and bound it to the nitrogen And then following that rule, I got two oxygens here and I put the oxygen on this nitrogen and the oxygen on that oxygen And then I drew the Lewis structure I counted my electrons, drew it up and there it is There is a Lewis structure But now what I am going to do is calculate the formal charge All of these atoms here, if I do it right, have a zero formal charge I then find a formal charge of plus one on the oxygen and minus one on the nitrogen And I see that the sum of the formal charges is zero And the overall charge on that molecule is zero, so it looks like I did everything right However, is this the correct Lewis structure for methyl nitrate? No It is not the correct structure for methyl nitrate And it isn’t because we have a negative formal charge on the nitrogen and a positive on the oxygen, and oxygen is more electronegative than nitrogen, so this is not an adequate structure for methyl nitrate This does not describe the chemical bonding in methyl nitrate What does? Well, to do that let’s look at the board here Let’s look at the bonding, here, in methyl nitrate Here is another Lewis structure that I could draw CH three, oxygen, and then I could have put the double bond here between the oxygen and the nitrogen, and then I could have bonded the two oxygens to that nitrogen And there is a bunch of lone pairs here on the oxygen That’s all OK But now, if I go and calculate the formal charges on that, I am going to get a plus one on this oxygen I am going to get a plus one on that nitrogen, and I am going to get a minus one on this oxygen and minus one on that oxygen That is a lot of distribution of charge, here, away from the distribution of charge in the isolated atom Let’s see if we can do a little better Again, starting with the methyl group here at the end, let’s do this Let us bond the oxygen to the carbon, and then singly bond that nitrogen to the oxygen, and then doubly bond one oxygen, and then singly bond the other oxygen And there is going to be a resonance structure to this because I could have switched where the double bonds were here And if I go and I calculate the

formal charges, I find now everything has got a zero, except the nitrogen has a plus one and this oxygen has a minus one And that is a much better situation than a lower energy situation, than a plus one on the oxygen and a minus one on the nitrogen There is the resonance structure I won’t draw it But that is the Lewis structure here for methyl nitrate Now, clue If you see an NO two written like that, that is always going to mean the two oxygens are bound to the nitrogen And if you ever see the word nitrate like in that expression, that means all of those oxygens are going to be bound to the nitrogen in some way On an exam, if you see an NO two, those two oxygens are going to be bound to the nitrogen If you see the word nitrate, the three oxygens are going to be bound to the nitrogen Yes? If I do that then I am going to have these five bonds to the nitrogen, and that is going to give a very high formal charge It is not going to be the lowest energy structure That is our structure But now the question is how to describe the bonding in this molecule Let’s do that Let’s describe that bonding Let me erase this structure here What do we have? We have three carbon-hydrogen bonds And this carbon here is bonded to four different atoms That carbon has no double bond, has no triple bond If it is bound to four different atoms and it has just single bonds, the carbon is always sp^3 hybridized That is something to know What that means is that these carbon-hydrogen bonds are sigma bonds They are sigma bonds formed between the carbon and the 2sp^3 wave function and the hydrogen 1s wave function That describes the bonding in the carbon-hydrogen bonds What about this bond, the carbon-oxygen bond here? How do we describe it? Well, we already said this carbon is sp^3 hybridized And so, we can write this carbon as sp^3 And then, this oxygen here, well, this oxygen has got two bonds to it It has no double bonds, no triple bonds, so this oxygen is also sp^3 hybridized This oxygen looks like the oxygen in water This is going to be a sigma bond It is going to be symmetric around that axis between carbon 2sp^3 and oxygen 2sp^3 We’ve got that bond Next we have an oxygen-nitrogen bond How do we describe the oxygen-nitrogen bond? Well, the oxygen, we already said was 2sp^3 hybridized We know that But this nitrogen has got a double bond to it If it has a double bond to it, well, that nitrogen is 2sp^2 hybridized But this is still a single bond between the oxygen and the nitrogen there It is symmetric And so that bond is a sigma between the nitrogen 2sp^2 wave function and the oxygen 2sp^3 Next the nitrogen-oxygen double bond, how are we going to describe that? Well, it is a double bond It means we have two bonds One of those bonds is a sigma bond, as I said It is going to be a sigma bond between the nitrogen 2sp^2 wave function and the oxygen 2sp^2

wave function Because oxygen here is also double bonded If we use that rule, we will consider the oxygen to be 2sp^2 It is a sigma bond But now we have two bonds, so the second one has to be a double bond What is that double bond going to be? Well, it is going to be between the nitrogen 2p wave function Because the pi bonds are always between the unhybridized wave functions Notice, I am going to leave out the x or the y here, because I don’t really know And, between the oxygen 2p wave function, I left out the x and the y there Then, finally, I have the nitrogen-oxygen bond, that second nitrogen-oxygen bond And, what do I have there? Well, it’s a single bond It is going to be sigma It is symmetric around the axis It is going to be between the nitrogen 2sp^2 wave function and the oxygen 2pz wave function It is going to be 2pz in that case because we are here along the bond axis It is sigma bond It is not a pi bond The sigma bonds are along the bond axis So that is methyl nitrate I am a little bit rushing to do something here, and that is I want to describe to you one other kind of bonding But this is a bonding that is not a bonding within the molecule It is actually bonding between molecules And this is called hydrogen bonding In hydrogen bonding, what you have to have is a hydrogen, and you have to have a hydrogen bonded to an electronegative element like oxygen A good example is water Water is bound to an electronegative element, and we’ve got two lone pairs But in hydrogen bonding you’ve got bonds between molecules This is intermolecular bonding And what happens is that this hydrogen here will interact very strongly with the lone pair electrons here on its neighboring oxygen, forming a bond It does so because this hydrogen is kind of deshielded The oxygen, being so electronegative, it has kind of pulled all the charge toward it This hydrogen kind of looks a little bit positively charged, delta plus where this is kind of delta minus And so this hydrogen being really small, it can get close to the oxygen lone pairs, where there is a lot of electron density, and form a bond And that bond ranges from 20 to 60 kilojoules per mole Certainly not as strong as a covalent bond A C-H bond is 400 kilojoules per mole, about the tenth of that strength And it turns out to be very important Hydrogen bonds determine the properties of water They determine the structure of proteins DNA owes its helical structure to hydrogen bonding Trees stand up straight because of hydrogen bonding in the cellulose chains The strength of nylon is determined by hydrogen bonding And whether or not you have a bad hair day is determined by hydrogen bonding For example, on the slides on the side, what you see is the protein of hair This is a polypeptide It is a repeating unit here of C-O, C-H, N-H, C-O, C-H, N-H again and again and again Here is another polypeptide or another peptide strain with this repeating unit Well, what happens, when your hair is actually wet, what happens is the hydrogens on the nitrogen, you can see in that chain up there — What happens is that they are

hydrogen bonded to water molecules And you can also see in the second chain over that the oxygen on the carbon here is hydrogen bonded to a water molecule When your hair is wet the actual polymers in your hair kind of slip by each other However, if you then take your hair and you put it some very strange configuration and you dry it, you remove these water molecules that are hydrogen bonded to your hair, what happens then is that these two chains now kind of lock into registry They kind of bond together because these water molecules are gone here And so now they hydrogen bond to each other The hydrogen bonds to the oxygen on the CO and the two chains are in registry And then, when you let your form go, well, your strands actually stay in that registry for a little bit until the humidity wipes that out Bad hair day See on Friday