 So this one says, which of the following of these, there may be more than one, can make hydrogen bonds with water? So in order to do this, you really want to know what the molecular formula of these things are. First thing we got to know is about hydrogen bonds. We need hydrogen in the actual structure, or we need an electronegative at, OK, one of those strong electronegative at. So which ones were those? Do you guys remember? Oxygen. Oxygen would be one. What were the other two? Hydrogen and fluorine, OK? So do you see any of these things that don't either have a hydrogen or an oxygen, fluorine, or nitrogen? Yeah, that N a plus. So already, we can get rid of that. So these molecules, let's now, the other four, let's expand their structures to see what their actual structures look like, OK? So this thing is called dimethyl ether. I'm sure you've seen the video by now of how to build this, so I'm not going to bore you with all the details. We're just going to do Lewis structures for us right now. This one's methane, and I know the same thing. Fluorine, diatomic, right there. And formic acid. This is the stuff that will enhance the steam. So is everybody OK with those structures? So in order to form hydrogen bonds with water, I have to, if I'm a molecule, have either lone pairs on me or hydrogens that are bonded to one of those three electronegative atoms, OK? Do I see any of these four molecules that don't have one of those two characteristics? So I either have to have a lone pair or hydrogens that are bonded to one of those three electronegative atoms. Yep, CH4 is now out, right? A super dipole-dipole interaction. So it's like a real strong dipole-dipole interaction. So to have a dipole, well, do I have to be, you guys remember? Do we see any molecules that aren't polar molecules? Yeah, F2, right? So that one's down now of the run. OK? So hopefully we see now I have two molecules up there that have either a- OK, this one also has a lone pair. OK, so what I'm going to do is erase everything up here, except for those two molecules, formic acid and di-nethylpethane. Is that OK with everybody? Everybody follow my logic? Everybody's OK with that, right? So if we remember, can only accept a hydrogen bond, because it doesn't have a hydrogen directly attached to that electronegative atom. OK, so this here, this molecule here, since it's got that oxygen with two lone pairs, we can say or we will say that it could make two hydrogen bonds with water, OK? But it can only accept hydrogen bonds from water, OK? So like that. So this, these lone pairs, are actually called hydrogen bond acceptors, OK? This has two hydrogen bond acceptors. Is everybody OK with that? No donors. So it doesn't have any hydrogen bond donors. Why? Because to be a donor, I have to have one of those electronegative atoms attached to a hydrogen. And I don't have that here. Of course, with water, it's got a donor. It's got two donors and two acceptors. Does everybody see that? So let's go over here to formic acid. Let's look at this top of. Does it have any acceptors? How many does it have? Two, right? How many donors does it have? None, this top oxygen, just the top oxygen, OK? Zero, right? Because it's only got the electron pairs. And that lets make it look more like Vespers theory, because we know that's an sp2 oxygen there. So we'll just show the two acceptors, OK? And I'll draw water in such a way to make it show that it's accepting those hydrogen bonds. Down here, do we have any acceptors on this oxygen? How many? Two. Very good. Same thing. What we said about hydrogen bonds, they have to be in line. That's why I'm drawing them, like that, the three atoms that I want, OK? One, two, three atoms that I want. One, two, three atoms that I want, OK? One, two, three atoms that I want, OK? I'm doing it on purpose, OK? So two more acceptors. Let's identify these. Is everybody OK with what I've done so far? And how many donors? One, right? So O H. And then it donates its hydrogen bond to the, what are we going to put here? The oxygen. The oxygen of water. That, so we have the one, two, three atoms, OK? So when we look at this, we call this thing a hydrogen bond donor, OK? So we wanted to say, well, how many donors do we have and how many acceptors in dimethyl ether? We have, what, zero donors and two acceptors. Total, what do we have donors and acceptors? So donors, we only have one. And acceptors, we have one, two, three, four, OK? So this can make hydrogen bonds, both donating them and accepting them. This one could only make hydrogen bonds if you've got the water molecules in there to donate them. So it can't make hydrogen bonds with itself. You want to think about it that way. This thing can make hydrogen bonds with itself because it's got both donors and acceptors. This one only got acceptors, so it can't make hydrogen bonds with itself. But it can't make with water. Any questions about that? OK, cool.