 Hi, I'm Stephen Nesheba, and I'm here to help you out with signing formal charges to non-metal atoms when those non-metal atoms are in a non-metal compound. And the basic idea here is that the formal charge tells us something about the excess of positive or negative charge on a given atom, and we get at that excess by saying, well, first we'll write down the number of valence electrons that an atom should have, and then we're gonna subtract away the number of electrons that are claimed by that atom, and you'll just see how that works here. So I'm gonna start off. I have this Lewis structure for carbon dioxide, and I'm gonna just start off on the left here. How many electrons does that oxygen claim? Well, I count one, two, three, four. Now those are long pairs, so only oxygen gets to claim those, but here's a couple of bonds, and each bond has two electrons, and since we think of them as shared electrons and a covalent bond, this oxygen gets to claim one electron for that bond and another electron for that bond. So what are we up to? One, two, three, four, five, six, okay? So that means the number of claimed is six. Oxygen has a valence of six electrons, so we come up with a difference of zero, and so we write it that way. How about that oxygen? Well, it looks like it's just gonna be the same as the first one. How about that carbon? Well, carbon has a valence of four, and how many electrons is it claiming? Well, I count one, two, three, four, one electron from each bond, so I get a difference of zero, and there we go. All formal charges are zero on carbon dioxide. I'll try NO2 now. I've already drawn a Lewis structure for NO2, and, well, this oxygen looks just like that one, so I know that that's gonna have a formal charge of zero. This oxygen is looking a little bit different now, right? The number of, well, valence electrons and oxygen, of course, is still six, but the number that it claims looks like one, two, three, four, five, six, seven, okay? So I have six minus seven is minus one, and I'll just draw it that way, okay? How about for that nitrogen right in the middle? Nitrogen has a valence of five, so we'll be looking to see how many it claims, and so that nitrogen, it claims that one lone electron up there, two, three, four. This, this nitrogen is only claiming four electrons, so I have five minus four is one, so it has a you know, we could put it that way, a plus one formal charge. Okay. Sometimes you have resonance structures, alternate resonance structures, and the formal charges can change according to where do you put the electron, so let's just do one right here. I'll just focus on that carbon right now. Carbon has a valence of four, and how many is this carbon claiming? Well, one for that bond, two, three, four, five. So four minus five, that's a, that's a minus one on that carbon, okay? And let's see about this carbon over here. It's the same, it's just another resonance structure, but now I can see that this carbon has one, it's claiming one, two, three, four, valence of four minus four, so now this has a formal charge of zero. Okay.