 Okay, let's do methane now, CH4. Okay, so what do we know already about methane? So methane is composed of two atoms, right? Two different types of atoms. They are both what? Types of atoms. Non-metals, okay? Non-metals. So since they're both non-metals, what are the bonds that are going to be formed between the atoms in this molecule? Covalent, okay? They're going to be sharing electrons. Why do they share electrons? Why doesn't one give it up to the other one? They both want to complete the octet, but couldn't they both complete the octet if they gave electrons away? No, they couldn't do that, okay? So let's see if they could. What would happen if I had? So let's just do this first. What, which one is the central atom here? C has to be the central atom. Why do you know that? Because H can only form one bond. Very good, okay? So C has to be the central atom. And how many valence electrons does C have around it? Four. So I have four H's, which we're saying are around this carbon, which is in the central atom. Or they're the peripheral atoms, if we will, right? So what you're saying is these, if I donated this electron to there, this electron to there, that to there, that to there, they wouldn't fill their octets? Everybody would, yeah, they would. Because it doesn't have any electrons in its valence shell. Anytime you, anytime you have a full valence shell, you're, you've got a complete octet, okay? Hydrogen can have a complete octet if it loses that electron or if it gains another electron, okay? Does that make sense? So if it's losing its electron, it completes its octet as well, okay? Octet is kind of a misnomer in the case of hydrogen, okay? So again, what am I, does everybody understand what I'm saying, does anybody, everybody get it? Why isn't it like that? Why don't we have something like this? Or, right, it's kind of like the same thing as NACL, right? If we did it this way, we could say CH4, okay? Same thing. Why doesn't it do that? What does it do? How about that? Let's compare what it does do. What does it do? Shares the electron. So draw that, have we drawn that yet? Is that what you drew? Well, we're going to eventually. These are the Lewis structures of the atoms. We're going to draw the Lewis structure of the molecule in a second. And I'm going to show you specifically what is actually called the Lewis structure, what's the perspective, blah, blah, blah, blah. Everybody understands this, right? Okay. Did you, so the next one, the next thing that we're going to draw here, this is called the Lewis structure, okay? So everybody draw the Lewis structure. That's the Lewis structure for methane. So again, why is it this and not this? What type of compound is this here? Ionic, okay. And this one? Covalent. Remember, this is not the right structure. This does not happen, okay? What do you mean? Why would it be ionic? Because it's a compound of ions. That's an ionic compound. What's another ionic compound you know? Sodium chloride, right? That's a compound of sodium plus and Cl minus, right? The same thing. Or, I don't know, magnesium chloride. It's two Cl minuses and one Mg2 plus, which is much, which is very similar to this compound here, right? Getting closer and closer to that compound. Why isn't it like this? And why is it like that? That's what we're asking. I thought you said that if you got eight electrons, you fill up an octet. Well, what about O2 minus? Why? This is a question that you want to ask yourself, why is it not like this? But what about O2 minus? Doesn't that have eight valence electrons and O dot only has six? Why can't carbon gain electrons and be O, or C4 minus? Why can N be N3 minus, but carbon can't be C4 minus? Yeah, that's not the reason. Carbon can be C4 minus in certain instances. Not in this instance, though. It's easier to share. Why, though? Why is that? Yeah, they both need them, right? But why do they both want to share them? Why isn't one pulling them away from the other one? That's what you want to ask yourself. It does, but what about when we have sodium and chlorine? Why do they, why does chlorine steal the electron from? Why does chlorine steal the electron from sodium? Because that would be against what you just said, right? So we're getting there. We're getting closer and closer. This is good to talk about, though. Okay, so we've got a metal, right? When we're talking about what? What compound are we talking about? Sodium chlorine, right? So sodium is a metal. Chlorine is a non-metal. So they're going to form an ionic bond, right? Okay, so we know that about methane, that carbon is a non-metal and hydrogen is a non-metal, so it's going to form a covalent bond, right? Why do non-metals and non-metals form covalent bonds, but metals and non-metals don't form them? No, why is that the rule? Yeah, that is the reason, but it's also the reason that the ionic compounds are more stable when they're not sharing. Why, though? That's the kicker, okay? It's because if you compared the electronegativities of these two elements, the electronegativities of hydrogen and carbon are very, very close to each other. The electronegativities of sodium and chlorine are very, very far apart from each other. Notice, huh? So there, so one of them, so electronegativity is like how strong you are to hold your electrons into your nucleus, okay, close to your nucleus. So sodium electronegativity, does anybody have an electronegativity table? Sodium's electronegativity is 0.9 relative to fluorines, or chlorines we were saying, which is 3, so that's very high relative to something that's very low, okay? So it's going to rip it away from it, but if we look at carbon and hydrogen, it's 2.5 to 2.1, very similar to each other, okay? So they need to share each other's electrons because they have close electronegativity values to each other, okay? Which is why this structure is no good, okay? Which is why nonmetals and nonmetals share electrons because they have electronegativity that are similar to each other. Their nuclei hold on to their electrons and add a similar strength, okay? That's what you want to think of. Okay, so this is called the Lewis structure here. Let's draw the perspective. I also will call this the structural formula. So did everybody build methane? Put it up if you built it. So notice that carbon has its bond angle set already in it. So you see that methane has this structure here. So I'm going to hold it like this and I'm going to show you how to draw it, okay? So perspective is drawing what I see here, okay? Notice if I'm holding this to where this angle here is in the plane of the board, okay? So this bond and this bond are both in the plane of the board and I look at it, I have one hydrogen that's coming towards me and one hydrogen that's going away. Do you see that? So let's draw what we see. The way to show bonds that are in the plane of the board are just with straight lines. We've got two of them. Let's put our hydrogens on them. So as everybody agree, that's what we see. Now we're going to draw the one coming towards us. We draw that with a wedge. Wedges mean coming towards. When we now draw the one behind here, we draw it with a hashed line. Okay? Like that, okay? So does everybody see that picture in this structure? So again, you've got to hold these in the plane, okay? So now do you see it? Okay? So this bond angle here is what? 109.5, yeah, degrees, okay? When we replace these bonds with electron pairs, it condenses that bond angle, okay? We'll talk about that later. This is a tetrahedral structure, yeah. That's just the orbitals going from atomic orbitals to molecular orbitals, okay? So going from an S. So here, what orbital is this electron in? The 1S orbital, right? Okay? This electron is in the what orbital? It's going to be in the 2P orbital, okay? So what you're going to have here is a hybrid between the S orbital of the hydrogen and the P orbital of the carbon, okay? And in fact, what you'll find is this orbital will be called an SP3 orbital. That's a little bit above the scope of this class. I know, is it, is it asked for that in the, on the paper? Okay, well, that's not that big of a deal, okay? So we can cross that SP3 because there's three, it's above, we'll talk about it next year in organic chemistry, okay? We'll talk about it next year in organic chemistry. Well, then you'll have, then you'll have to talk about it with somebody else in organic, okay? Are there any more questions about methane here? Again, here, I'll just, before we leave, I'll show the structure one more time to everyone and the video camera, I guess. Okay, guys, so what I'd like you guys to do is continue along with this exercise.