Resonance and Bond Length

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Nicole Gamboa 2M
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Resonance and Bond Length

Postby Nicole Gamboa 2M » Sun Oct 23, 2016 12:30 am

Hi All,
I was going over my notes on resonance and bond length and I found myself pretty confused on how resonance affects the length of a bond and why the bond in a structure with resonance is experimentally observed as the average between two bond lengths rather than a single shorter or longer bond?

Joseph Nguyen 3L
Posts: 24
Joined: Fri Jul 22, 2016 3:00 am

Re: Resonance and Bond Length

Postby Joseph Nguyen 3L » Sun Oct 23, 2016 1:47 pm

You see, the Lewis structure is an imperfect model for "representing" bonds. For a resonance structure, the double bonds can be in different locations, and let's say a double bond is 1A in length but a single bond is 2A because it is larger. But when you do the experiment, you find that all of the bonds have a length of 1.5. Resonance structures are only meant to show that those lengths and bonds BLEND together as an average because electrons are delocalized, meaning the electrons don't stay in any ONE lone pair. Therefore the electrons are distributed evenly throughout the molecule, creating resonance.

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