Question
Sat April 23, 2011 By:

Why does resonance occur?

Expert Reply
Sat April 23, 2011
Resonance in molecules is a type of electron delocalization. Since electrons repel, if the electrons spread out, it can lead to greater stability.

Since the electrons are spreading out between the two states ("resonance structures"), neither of those structures are really a good way to represent the molecule. The closest model of the molecule is a hybrid of the two, with the electrons smeared out over both spots where the double bond can exist. 
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