 Let's do this one instead. OPCL30. OK, so this is phosphoryl fluoride. Not something that you need to memorize or anything. But hopefully this one makes sense to you. So if you looked at this, hopefully you would think the phosphorous should be the central atom. OK, because it's period three or below, and it can expand its base. So when we do that, draw phosphorous, fluid structure, and then draw your three corners. Osphorous is going to expand its balance in this case. Normally you would only think of it to be making three bonds, because that would fill up its octet. We're going to use these electrons. OK, so I know this looks like there's 90-degree bond angles, but this is just the fluid structure, and the fluid structure doesn't give us any kind of molecular perspective information as to the bond angles or anything like that. But, so can I erase this part? Everybody good with that? So let's go ahead and look at the... How do we determine the bonding? How about that? You guys remember that? Well, so we have to figure out how many... We use the electron density. Yeah, electron density, groups of electron density. And how many do we have around here? Four. So when we have four, the electronic structure is going to be what? Tetrahedral. And are all four of those electron density groups bonds? Yes. So what would you expect the molecular geometry to be? Tetrahedral. So when you drew it, why don't you guys try to draw this on your own and then compare it to my drawing up here? OK, so draw it on your own and I'll draw it up here. Don't look up here until you've done your drawing. OK. Like it coming out at you. Yeah, the perspective. So, I mean, whichever way you wanted to draw it, like, again, you could draw it like this or draw it like this or let's see if I have... a resonance structure of something like this, right? So how would I do a resonance structure? Remember, resonance is just moving the electrons, not any of the atoms, right? A single one on the oxygen. Yeah, so you would take... So let's erase this one over here. We'll take this double bond and move those electrons up there. Remember, you're double headed arrow. What are you doing? Remember your resonance arrows? If you're having a hard time with formal charges, then make sure you use the formal charge calculation. If you're good at counting electrons, remember the charge separation. So these are resonance forms of the same molecule. OK. So this molecule is kind of a hybrid of both of these forms. What would you predict the bond angle to be here? 109.5 would be a good prediction, right? But do you recall, and remember, we didn't talk very much about this, but when you have a huge, a big central atom, do you remember what it does to that bond angle? Yeah, it pushes it down a little bit. So you would expect this to be less than 109.5. OK, that's probably the best. Yeah, well, no. That was because of the low and parallel electrons. But when you have a bigger atom, you know, if you want to think about H2O relative to SH2, you know, so like SH2 has a bond angle of 92 degrees as opposed to 1 to the 4.5. So you have the 107 when there's a lone, like if there was, the oxygen wasn't there and there was a lone pair of electrons above phosphorus. Yeah, then you would expect it to be 107.3 like if you're comparing it to this structure. And that's the little, like, trigonal plane you're being? Well, trigonal parenyl, right? OK. But expect this to be 107.3 of this bond angle here. Well, why? Because there's a lot of electrons that kind of squishes the dam. But you should predict that that bond angle might even be smaller because this is a huge central atom. OK, so you're going to expect this to be less than 107.3. And probably this one, 109.5 would be a good prediction. But you would think, OK, since it's got a big central atom, it must be less than 109.5. How would you ask a question like that I mean, like I said, I didn't emphasize it very much. I just thought it would be good to talk about during the video, you know. So I would probably expect you to guess 109.5 on this one. So, are there any other questions on something like this?