 Okay, so let's try a bigger structure. Let's try this one. So C3H8. This can only be built in one way. The name of this molecule is propane. So remember, we could draw it like this, so if we go back, right? So we call this the molecular formula, right? We could draw the expanded structural formula. So how would that be drawn? So we know that the hydrogens have to all be bonded to what other atom? Carbon, right? Because if they were bonded to a hydrogen, what would happen? It would be H2 gas, right? And that's a different molecule, okay? So all your hydrogens have to be bonded to carbon, okay? So what does that mean about your carbon atoms? What do they have to be bonded to? Hydrogen and carbon, okay? They have to be bonded to themselves, okay? So there's only one way this carbon chain can be made. Once we get to four, then you can kind of start making them different ways. And we'll talk about that later. And then, of course, each of those hydrogens can be stuck on those carbons like that. So notice what I didn't do this time. I didn't show the fish hooks, right? Why? Because it's getting bigger and bigger. So you can imagine the next one is butane, the next one is pentane. If you do all those fish hooks, you're going to have to have a paper that's enormous, you know, to be able to do this. So you've got to kind of skip that step, okay? So you've got to get it in your head what these molecules are going to start looking like. So this is the expanded structural formula. Remember, we said that we could build molecules of them? So the ball and stick formula of this, okay? And then emphasizing, or the skeletal structure I've been calling it, right? Emphasizing the bonds, okay? Notice each one of these carbon atoms looks like the carbon atom in methane, where it's got that 109.5 degree bonding. So if we're looking at this thing here, this is like the Lewis structure of it, right? This doesn't show any, you know, bond angle information, okay? So in order to draw the Vesper theory structure or whatever, the molecular structure of this thing, we're going to have to remember our bonding, okay? The way I like to do it is always draw the carbon backbone as much of it as I can in the same plane, okay? So remember when we draw things in the same plane, they're just straight lines, okay? So there's three of them and we know that it helps you to build models. You're more than welcome to buy a model kit and bring it to your test if you want to. Most people don't like to buy a model kit, but if you want to, you're more than welcome. But anyways, if you don't remember, right, you can think of just this middle carbon being like methane, right? And knowing that there's a 109 bond angle around it, 190 degree bond angle. So what does it look like? It's got two bonds in the plane and two bonds out of the plane. If we want those bonds in the plane to be as many carbons as possible, then put carbon and carbon there. Hydrogen, hydrogen there, right? And then, of course, just like this one, this carbon here, this carbon here is going to have two in the plane and two out of the plane. So we'll put the two in the plane. The two out of the plane, put them on the other side. Why? Because you can see here, right? The two out of the plane are on the bottom. Here are the two out of the plane are on the top, okay? It's just the easiest way to draw. You could draw it like that, right? But it gets kind of confusing, especially for introductory chemistry students. If you drew it the other way, it would be fun. Totally fun. I won't mind, but it just would get confusing for you guys. So I'll pass this around for you guys to check it out. So what I'm saying is, like if you look here, you can see all these carbons are in the plane. These two hydrogens are out of the plane. If I stick it like this, we can keep this hydrogen in the plane here and these two, like bunny ears, are out of the plane. Like I said, last time, like bunny feet or something like that, in bunny ears or something. So, anyway, down in the plane. Asked you, what is the bond angle here? What would you say? 109.5. Whenever you see an atom, as far as you guys are concerned, whenever you see an atom that's surrounded by four bonds, okay, like this carbon here, and no lone pairs, okay? If you see that, four bonds of no lone pairs. I want you to think of it as 109.5, okay? That's all I want you to remember for that type of arrangement. Is everybody okay with this one? What if I asked you, what's the bond angle between those two hydrogen atoms there? 109.5. In fact, all the bond angles in this molecule are 109.5. Okay, so this molecule is propane. This is the stuff that you, I don't know, grill in the backyard grill or whatever. If you're like Hank Hill, right, propane and propane, it says. Are there any questions? Oh, we could draw, let's draw the condensed structural formula and the bond line formula before we turn this one off, okay? So, do you guys think you could draw the condensed structure? What would it be? Tell me. CH3, H2, H3. Yeah, that's the condensed structure, like that. Okay, and what about the bond line structure? Do you guys think you could do that? It's easy if you get here, you just draw the carbon backbone. So, what is it? Looks like a little bird when you were in kindergarten or whatever, right? So, is there anything else? Oh, so here's the bond and stick formula and here is the space building model. So, you can see what it really looks like, right? So, the difference between, this emphasizes bonds, this emphasizes what the molecule really looks like, okay? Okay, any questions before I kill it? This is called the bond line structure. Is that butane? That's a different molecule. That's a different molecule. That's got four carbon atoms. No question. For the condensed structure, could we be able to do CH3 squared CH2? You mean, that's not a squared, but you mean subscript 2? No, don't do that. Just, you're making it too hard on yourself, okay? I mean, they're doing it that way because those two CH2's are in the middle, okay? Just like what we talked about on Friday, if you recall our conversation then, okay? So, if they're next to each other, then you can put them like that. If you want to be harder on yourself. But like I said, you don't have to, okay? Any other questions on that one? It's a good question though, okay? So, it just makes it harder on. And in fact, in this case, you know, it's not the same because if I did that, right, what is she saying? I mean, yeah, what you're saying, you're emphasizing this carbon. You're kind of emphasizing it like that. Out of this carbon, we've got two methyl groups, okay? You can say that, okay? But it starts to get confusing especially for an introductory chemistry student. If I want, if I'm an introductory chemistry student and I say, if somebody tells me to draw the condensed formula, I'll just draw this fluid structure first and then just one down, one down, one down, okay? You can't do this. Again, it's not wrong, okay? But once you start to do this, like with bigger structures, it will become wrong, okay? We can do other structures where it'll totally be wrong and I'll show you. Any other questions? Okay.