Resonance structure and formal charges

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Maldonado3K
Posts: 39
Joined: Fri Sep 29, 2017 7:07 am

Resonance structure and formal charges

Postby Maldonado3K » Sun Nov 05, 2017 11:53 pm

Does anyone have a simpler method or clear trick to easily determining the dominant resonance structure of an ion by calculating the formal charges on the atom? or simply something that reminds them of the steps to achieving this?

Alexia Joseph 2B
Posts: 56
Joined: Thu Jul 27, 2017 3:01 am

Re: Resonance structure and formal charges

Postby Alexia Joseph 2B » Mon Nov 06, 2017 12:21 am

I find that it's the easiest to remember the formula (FC=V-L+S/2), where the number of valence electrons is V, the number of of bonding electrons are S, and the number of lone pair electrons is L. A formal charge of 0 is the most stable.

Andrea ORiordan 1L
Posts: 52
Joined: Fri Sep 29, 2017 7:04 am
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Re: Resonance structure and formal charges

Postby Andrea ORiordan 1L » Tue Nov 07, 2017 11:39 am

You kind of just have to experiment a little bit. There's also an easier way to figure out formal charge- you just count the number of electrons the bonded atom controls (count a bond as one electron and a lone pair as two) and compare it to the number of valence electrons it normally has. If it controls more than it normally would have on its own, it has a negative formal charge equalling however many more electrons it has in its bonded state, and vice versa if it has fewer electrons than it normally would have (and a positive formal charge).


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