if i send somone an email about a resonance struncture will somone help me

[ManBearPig]

we had this test a while ago and i missed this problem, and im trying to figure out why. if i send someone a jpeg with the solution will they tell me why it doesnt keep going on? ahhhhhhhhhhhhhhh

 

[uclaLabrat]

ygpm

 

[uclaLabrat]

and the answer is....

pi orbitals. Specifically, alkene carbons are sp2 hybridized, where the p orbital is used to make the pi bond. So in the resonance structure, the electrons can move around into the adjacent p orbitals, which allows the resonance to happen. Going around the ring (counterclockwise, from the substituent) the 5 and 6 carbons have filled orbitals (in the form of C-H bonds, sp3 hybridized) so those orbitals aren't available to participate in the resonance.

If you need any more clarification, let me know.