 So let's do the valence or build the structure using those dot structures, okay? So what is the structure we're looking for? CO3 2-minus. Okay, again the book teaches you to count up all your electrons, add your 2-minus electrons and so on and it's effectively the way that we're going to do it here, but we're going to do it all through Lewis structures, okay? So hopefully by now You're content to say that the carbons probably the central lab, okay? Because it can make the most fun So we'll put it in the center And we'll draw this Lewis structure, okay? Then there's probably three oxygens around that central carbon So let's draw those three oxygens And we'll draw their Lewis structures, so notice there's two minuses on this Molecule or this ion, right? So we've got to add two more electrons to our Lewis structure The electrons will be added to the atom that has the highest electronegative Which one of those is is a carbon or oxygen? Oxygen, okay, so which oxygen has the highest electronegativity this one this one or this one? They're all the same, okay So the best way to do this is to add one electron to one oxygen one electron to the other oxygen Okay, and because things don't like to have a two minus charge like one atom Doesn't like to have a two minus charge if it can be dispersed over various atoms. Is that okay? So let's add an electron to two of these oxygens, and I'm just gonna pick two randomly, okay? Not really randomly because the way I like to draw this structure is this way So there's one of the electrons and there's the other one. Is everybody okay with that? So I put those two minuses in there. Now let's build our and if you really want to you can put Your minuses there already because we're going to eventually they're gonna have a formal charge of negative one Let's go ahead and build our structure So fish of caros Fish of caros and this one needs to this one needs to So let's just draw it And again, this is the Lewis structure. We're not gonna talk about Vesper yet. Okay, of course I skipped that intermediate Because hopefully by now you can convert So you guys think you can do that The thing about these polyatomic ions is you got to remember to put your Electrons in there. Okay, and put them on the most electronegative that Okay So does everybody okay with this? We're gonna talk about resonance now, which is what which is the topic. We're gonna hit later But this is a very good Structure to talk about resonance with okay, so Why should it that then why should it be that this and this oxygen have a negative charge? And this one doesn't anybody give me any explanation for that and why did I choose those two to have the negative charge? Yeah, they happen, but why didn't I add it to the other one? I? Could have yeah, that's the whole point is I could have you know I just didn't because you know I like to draw it this way this way more than I like to draw the single-bond Here, okay, but they're equally valid structures, okay So where you can make two equally valid structures by only moving? Electrons, okay, those are called what we call resonance structures Why are they called resonance because you resonate from one structure to another and in fact they are equivalent structures So how am I what am I even talking about right? So let's just show some resonance structures, okay? So remember our single-headed arrows or fish of arrows We're going to compare those with what arrows we're going to make now for resonance Okay, so we're going to draw a resonance structure of this molecule here So we're going to take two two electrons from this oxygen and bounce them into this bond here Okay, that's going to make a double bond there is everybody okay with that Notice the double-headed arrow that means the motion of two electrons is everybody okay with that? Okay, okay, okay But we can't have the double bond here a double bond here in a single bond here right because carbon can only make four bonds Okay, very important So when we do that we're going to have to bounce The bonded electrons out to that other oxygen Okay, is everybody okay with that? So when we do that we draw we make a resonance structure So notice the resonance arrow double-headed arrow Okay, another chemistry is the language of arrows. Okay, so you got all these different arrows for different things So when we do that, we're just going to draw what we call the resonance structure. Doesn't make sense Okay, could we draw is there another resonance structure for this molecule? Yeah, how would you do it if we start from here? What would we do take this like that? Okay, let's draw our resonance arrow like that. Everybody okay, so this molecule has three structures. It actually has another one Which we won't get into because it's gives it starts to get weird because the Carbon's octet won't be filled, you know, but for right now since you guys are introduced to resonance This is good enough. Are there any questions about what I've done up here? Okay, because you're going to be asked to You know perform some of these motions with these electrons