Texts 5 for each structure below draw the best two...

Texts: 5. For each structure below, draw the best two additional resonance structures. Include lone pairs and formal charges where applicable. 3 points for each best additional resonance structure. a) (e) Rank the resonance structures A-C below in terms of best to worst contributing. 1=best, 3=worst. Then, provide a very brief explanation (no more than two sentences) to justify the best one. (2 points for ranking, 3 points for valid explanation) A B C Explanation: 6. For each molecular formula below, draw a valid Lewis structure (bond-line structure also fine). Each atom should be neutral and obey the octet rule. Include lone electron pairs where applicable. It will be helpful to determine the degrees of unsaturation first. 3 points for each valid structure. a) CBrN b) C2H6

Transcript

00:02 Okay, so we need to draw three resonant structures for cno minus isocyanate minus.

00:09 Well, in this order, it's not isosanate, but in either case, we're told that the skeletal structure is c and o.

00:22 Right, and then let's figure out how many electrons we have to work with.

00:26 Carbon brings four, nitrogen brings five, oxygen brings six, and our negative charge brings one.

00:39 That's a total of 16 electrons.

00:43 Great.

00:48 Yeah, so let's start things up here.

00:57 What else do they tell us? okay, resident structures.

01:02 Draw three resident structures.

01:06 And then select the best based on formal charge.

01:13 Okay.

01:14 All right.

01:16 Well, let's start with the following.

01:19 Going.

01:21 Basically, we know that carbon, out of all of these, is the least likely to want to have negative charge, right? for that reason, it's, carbon always wants to have four bonds.

01:34 We can't give it four bonds without giving it a quadruple bonded nitrogen, which just isn't going to happen without breaking nitrogen's full octet, right? because it's always going to have this bond of oxygen as well.

01:45 So the closest we can get to giving carbon, four bonds would be to give you.

01:49 Give it three bonds and a lone pair.

01:53 Okay.

01:53 And then how many electrons? this is this? two, four, six, eight, ten.

02:00 What have we got left? we've got three lone pairs left, right? so those would go on oxygen.

02:08 Okay.

02:09 So this is one possible structure.

02:11 This would put a positive, sorry, a negative charge on carbon, a positive charge on nitrogen, and a negative charge on oxygen.

02:22 At this point, now we can start looking at resonant structures.

02:25 Right.

02:26 So this is probably going to to be the best because any additional resident structures are going to start messing with the charge on carbon and start giving it multiple charges that is we can't really move anything around without also moving around these triple bonds and turning them into loan pairs on carbon if we want to maintain a full octet so the first maybe obvious thing we could do would be to turn one of these loan pairs into a bond and turn one of these bonds into a loan pair to give us this resonant structure.

03:00 Now all of a sudden, carbon's got two loan pairs and a double negative charge...

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