## When to calculate formal charge

$FC=V-(L+\frac{S}{2})$

Rebecca Epner 4A
Posts: 53
Joined: Sat Aug 17, 2019 12:18 am

### When to calculate formal charge

Do you always have to compute formal charge when drawing Lewis structures?

chrisleung-2J
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### Re: When to calculate formal charge

I believe that at this level we would need to account for formal charge as we draw Lewis Structures, as formal charge allows us to determine which Lewis structure is the most correct one.

Jorja De Jesus 2C
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Joined: Sat Jul 20, 2019 12:15 am

### Re: When to calculate formal charge

I don't think you would have to calculate formal charge all the time, I think it would just be when it is being asked for in a problem. Another instance where you most likely will have to calculate it might be when you have to adjust the lewis structure so that all the atoms are stable at a formal charge of 0. Even with that, I think if we are given a problem, it would be stated clearly if they want us to find the formal charge of something.

JinwooLee_1F
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Joined: Sat Aug 17, 2019 12:15 am

### Re: When to calculate formal charge

It would take a lot of time to do formal charge for each lewis structures. It would be best to do them when there are two or more possible structures for one molecule, and you do not know which one is the most favorable one.

Debora Fernandez Clemente_ 4H
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### Re: When to calculate formal charge

When determining the most stable structure do you choose the Lewis structure with the least formal charges on each atom?

Drake Choi_1I
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Joined: Sat Aug 17, 2019 12:15 am

### Re: When to calculate formal charge

Debora Fernandez Clemente_ 4H wrote:When determining the most stable structure do you choose the Lewis structure with the least formal charges on each atom?
Yes that is correct. Hope this helps! :)

405268063
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Joined: Thu Jul 25, 2019 12:17 am

### Re: When to calculate formal charge

Yes, you would want to get the FC as close to zero as possible to get the most stable Lewis structure.

Tahlia Mullins
Posts: 105
Joined: Thu Jul 25, 2019 12:15 am

### Re: When to calculate formal charge

I do not think it is absolutely necessary every time, but it is a good way to check that the lewis structure is the best possible for the molecule.