July 08, 2020, 12:51:08 AM
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Topic: Valid Resonance Structure  (Read 196 times)

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Offline AcceleratorLvL5

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Valid Resonance Structure
« on: July 01, 2020, 06:44:40 AM »
Hello there,

I am doing resonance exercises and wanted to know if the following resonance structure (with a question mark) is valid. (If it isn't could you please elaborate why:)

Thanks!

Offline Babcock_Hall

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Re: Valid Resonance Structure
« Reply #1 on: July 01, 2020, 07:48:46 AM »
It is a forum rule that you must give your thoughts before we can help you.  What criteria do you know for judging resonance structures?

Offline AcceleratorLvL5

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Re: Valid Resonance Structure
« Reply #2 on: July 01, 2020, 09:26:32 AM »
Well, in a resonance structure only electrons (and therefore charges) move.
The negative nitrogen has 8 electrons fulfilling the octet rule but only 2 bonds and is therefore negatively charged.
It can then push one free electron pair onto the sp2 hybridized carbon and create a π-bond but due to carbon only being able to have four bonds the π-bond between the two carbons is removed and the electron pair shifts onto the "left" carbon as a free electron pair.

I think the third resonance structure doesn't work since the carbon directly bonded to the nitrogen would exceed the octet rule if it would get another free electron pair from nitrogen, so only the first to should be valid if I'm correct?

Offline Babcock_Hall

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Re: Valid Resonance Structure
« Reply #3 on: July 01, 2020, 10:32:18 AM »
I agree.  Sometimes I find it to be helpful to draw out the hydrogens, to make counting the total number of electrons easier.

Offline AcceleratorLvL5

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Re: Valid Resonance Structure
« Reply #4 on: July 01, 2020, 10:51:59 AM »
Thanks for the confirmation :)
I will start drawing them as well (if the structure is more complicated).

Offline rolnor

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Re: Valid Resonance Structure
« Reply #5 on: July 01, 2020, 02:19:17 PM »

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