 OK, let's do this next one. Let's show the reaction between the constituent elements to make the molecule phosphorous trichloride. OK, so it gives you the name of the molecule. So if you recall how to name covalent compounds, you'll know that the molecular formula of this compound is PCL3. So how did I know it's a covalent compound? Well, because phosphorous and chlorine are both non-metals. So I should have been able to figure out, let's just do this for right now, OK? So phosphorous trichloride. So let's draw the Lewis structures of phosphorous and chlorine. So which one is going to be the central atom? So if you recall the Lewis structure drawing rules that we went over, hydrogen and all of the halogens can only make one bond in these simple Lewis structures. So you would expect that the chlorines would be on the outside of the molecule and phosphorous to be on the inside of the molecule. You would also see that once you drew the Lewis structures of these atoms, that phosphorous will have like three little arms that will be able to grab three different atoms. And chlorine will only have one arm each. So that should also clue you in as to where the position of these atoms should be relative to each other. But anyways, let's draw them out. So phosphorous, group 15. So it's going to have five valence electrons. So one, two. And you can see there that it could fit one, two, three more in its valence shelf. So phosphorous can actually expand its valence shelf. We'll talk about that a little bit later. And you can start adding more than just the three atoms that we're depicting here. And we'll build some of these molecules, what we call expanded valence molecules like PCL5, for example, later. But for right now, let's do these simple molecules. So chlorine has the seven valence electrons. And again, I'm just going to put the one electron on the side of phosphorous atom. Because remember, I'm going to make those phosphorous. So again, empty spot, empty orbital, next to the phosphorous, not conventional to do. Draw what happened here. So remember, phosphorous, only one head of the arrow, because like what we said before, double-headed arrows mean two electrons. Single-headed arrows mean one electron limit. One electron limit, one electron limit on to each other. So like holding hands, when we show that, we show that as a line. We still show the non-bonding valence electrons of the particular atoms. And we'll point those out here in a second. So I'll show another line. I have two bonding electrons in them. So two, four, six bonding electrons around the central atom. And non-bonding electrons. We can do the same around the chlorines, too, in this. So the bonding electron, as you guys are getting it, I'll add some more from earlier recordings, and should be enough, I think.