 Okay, so let's come up with a compound that is composed of only silicon and chlorine atoms, okay? So how do I do that? Well, I've already done the chlorine part, let's do that again. So the first thing I would wanna do is write out the two atoms. So silicon is Si, and then write out its Lewis structure, okay? So one, two, three, four. So from what we said, how many bonds do you think silicon is going to be making? Four. Four, okay? And chlorine, remember, one, two, three, four, five, six, seven. So how many bonds is chlorine gonna make? One, so how many chlorines do you think you'll need for silicon? Four. Four, okay? So what I do, and again if you can do this in your head, you don't have to count one, two, three, four, five, six, seven every time. But I like to keep that lone electron next to the other atom. So now we're gonna make a covalent compound by attaching these two electrons together. So we're going to essentially make them get into their own orbital together, all the hybridized orbital, and we'll talk about that more later. So notice the arrows here, we call them fissure arrows, okay? They're half arrows, you guys see that? So half headed arrows. So notice they're all meeting in between. They're not like being donated to the silicon, okay? So they're sharing these electrons, remember? Sharing. So when we draw the structure, it's gonna be silicon with a covalent bond and chlorine with all of its valence electron still show. The thing you wanna know is that, can I erase this? The other thing you wanna know is that this drawing is on a two dimensional surface, but it's a three dimensional molecule, okay? It's a three dimensional object. So the Vesper theory states, so we'll be talking about Vesper theory a lot, the Vesper theory is valence shell electron pair repulsion, okay, Vesper. And I know that's not how you spell Vesper, but that's what they say, okay? It's like the separate or something like that. But anyways, we call it Vesper. And the valence shell electrons repulse each other, okay? That's the theory of Vesper. They hate each other, okay? So they wanna be as far away from each other as possible. So in order to do that, on a two dimensional surface, it might appear as 90 degrees being as far away from each other as they could possibly get. But these aren't two dimensional objects, okay? They're three dimensional objects. So in fact, they can get further away from each other than 90 degrees, okay? So the furthest four things can get away from each other is 109.5 degrees. So that's a number you're going to have to memorize, okay? You haven't memorized it already. So we're gonna draw what the actual structure of this molecule looks like. And again, this is still a three dimensional representation on a two dimensional board. But whenever you've got bonds that are just straight lines like that, that straight line, those mean that they're in the plane of the board, okay? When you've got something that looks like this, we call that a wedge, wedge bond. So that means it's coming towards us. And then there's another type of a bond. It's called a hashed bond. So you see the hash marking like that, okay? So hopefully you guys can see the three dimensionality to that if you can't. I'm gonna bring some models in next time and I'll pass them around and stuff, okay? So the thing is, is like I said, there's a bond angle here. Bond angle measures from the angle from bond to bond as you would imagine, okay? It's not a measurement of here to here. It's the bond to bond, okay? So this bond angle is 109.5 degrees and hopefully you guys can see that's bigger than 90 degrees, okay? So that's better for electrons because they don't wanna be near each other, okay? So again, three dimensional shape, best for theory, we'll get into it more more and more and more, this next one, okay? So any questions on this one? I know we're just starting out with this so I wouldn't follow you for not having any. Okay, cool.