a. Draw the resonance forms for SO2 (bonded OSO )

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Accepted Answer

Hey everyone, let's solve this. It reads show all the possible resonance structures of S. 03 or sulfur trioxide. So first we're going to count the total number of valence electrons for this structure which we add up the valence electrons for each individual atom in the structure which we get from the group number on the periodic table. Right then we're going to draw sort of like a rough draft lewis structure just to see what we're working with. And we'll start by just doing stigma bonds and then completing the octet with some lone pairs. And then once we see the formal charges, see what oct it's need to be still further completed, we can draw our resonant structures. Okay, so let's give it a shot. So we have S. 03 which sulfur has six valence electrons. Oxygen also has six because they're in the same group. So six times three is 18. So this is 24 valence electrons. Okay, so let's draw s so three sulfur is going to be our central atom. Okay, so if I attach those oxygen's with sigma bonds that only uses six valence electrons. So we need 18 more Which is nine loan pairs. So I have three oxygen atoms. So I'm going to add three lone pairs. Three sets of lone bears to each of those oxygen atoms. Okay, so 246, 8, 10, 12, 14, 16, 18. Okay, so now let's see what formal charges we have. See what needs to be. How can we make these atoms in this molecule more happy, more stable. So what formal charges do we have? Oxygen? They all look the same. Each oxygen And they all have a formal charge. Of what? Well, it has oxygen likes to have six valence electrons and it has seven touching it. Right? 1234567. So each oxygen is going to have a negative one formal charge. Okay. And what about sulfur? Well, we said Sulfur also likes to have six, but this sulfur only has three electrons touching it. One from each of those sigma bonds. So this has a positive three formal charge. That's pretty extreme. We don't usually see that. So what else do we notice about the stability or the happiness of these atoms? The oxygen's their octet are full despite even though they have the formal charge. But this sulfur the octet is not complete. Right? It only has six electrons two from each sigma bond. So I think this oxygen, one of the oxygen's is going to donate alone, pared down uh to I guess share rather than donate with share its electrons with that central sulfur atom. Let's see what that looks like. So we have sulfur. And now let's double bond that left hand oxygen. And then the other oxygen still have a negative charge. Okay, now sulfur is happier. Right? It has eight. Its octet is satisfied. And it still has a plus two formal charge, but that's better than a plus three. So we'll go with that. And are there any other resonance structures we could have? Yeah, we have two oxygen's that are just like this oxygen. That's double bond. So we can sort of copy and paste the structure, giving each oxygen a chance to have the double bond. Okay, and when we draw resonance structures, we put them in brackets. We have the double arrows going in between the structures. So this is the final answer for this problem. I hope this video is helpful, and thanks for watching.

a. Draw the resonance forms for SO2 (bonded OSO )

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