Formal Charge


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305113590
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Joined: Fri Sep 28, 2018 12:28 am

Formal Charge

Postby 305113590 » Sun Nov 04, 2018 1:36 pm

Is it necessary to check if the Lewis structure is the best one by determining the formal charge of each atom? For example, when COCl2 has a double bond with oxygen and the rest have single bonds, then all formal charges equal 0. But when there is a double bond with Cl, then it begins to change.

If so, is there an efficient way to determine which Lewis structure is the best?

Chem_Mod
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Re: Formal Charge

Postby Chem_Mod » Sun Nov 04, 2018 1:51 pm

You generally want to minimize the number of charges, even if the overall charges equal 0. So, if one structure has no charges, it is better than a structure that has a positive and negative charge that cancel each other out.

Krisdylle Repollo 4H
Posts: 33
Joined: Fri Sep 28, 2018 12:28 am

Re: Formal Charge

Postby Krisdylle Repollo 4H » Sun Nov 04, 2018 1:51 pm

I think it was mentioned in the review sessions that the only way to determine which Lewis Structure is the most accurate is to find the formal charges of each atom. By finding the formal charges of each structure, the best one would be where the charges are closest to zero.

RandallNeeDis3K
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Joined: Fri Sep 28, 2018 12:25 am

Re: Formal Charge

Postby RandallNeeDis3K » Sun Nov 04, 2018 2:04 pm

The key is to minimize the charges to the charge of the molecule given. An quicker way to see the formal charge of an atom is to: 1) Find out how many valence electrons there is and 2) subtract the number of dots (lone pair electrons, count each one) and lines (shared bonds) around it.


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