## Formal charge

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

Andrea_1H
Posts: 50
Joined: Wed Sep 18, 2019 12:18 am

### Formal charge

What if we can’t get all the atoms to have a formal charge of 0? Is there a “second best” option?

Sidharth D 1E
Posts: 98
Joined: Sat Aug 24, 2019 12:17 am

### Re: Formal charge

The next best option is to have the most elements with a formal charge of 0, with negative formal charges with the most electronegative elements of the molecule and positive formal charges with the most electropositive elements of the molecule.

Maya Serota 3G
Posts: 53
Joined: Tue Sep 24, 2019 12:17 am

### Re: Formal charge

You just want to get as close to 0 as possible.

Eesha Sohail 1D
Posts: 100
Joined: Sat Aug 17, 2019 12:16 am

### Re: Formal charge

If they can't all be zero, then the next course of action is to find the configuration that allows for the lowest possible charge, whatever that might be.

Sanjana K - 2F
Posts: 102
Joined: Sat Sep 07, 2019 12:17 am
Been upvoted: 1 time

### Re: Formal charge

If you can't narrow it down, you might want the negative formal charge to be on the more electronegative atom. For example, you can refer to #12 on the Dino Nuggets Midterm, where we ultimately chose our structure to be N --- N - O instead of N -- N -- O because we'd rather have the -1 charge on the oxygen atom than the -1 charge on the nitrogen atom (since oxygen is more electronegative than nitrogen) so it'll tend to attract the electrons more.

SVajragiri_1C
Posts: 115
Joined: Thu Jul 11, 2019 12:16 am

### Re: Formal charge

Just make sure the formal charges are as close to 0 as possible.

quresh3E
Posts: 36
Joined: Wed Sep 18, 2019 12:17 am

### Re: Formal charge

The added formal charges of the atoms should be zero. With whatever negative formal charges being on the most electronegative atom.

jmtz1I
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Joined: Wed Sep 18, 2019 12:15 am

### Re: Formal charge

The best thing is to have a formal charge of 0, but if not my TA stated to find the lowest possible charge.

Abigail_Hagen2G
Posts: 107
Joined: Fri Aug 09, 2019 12:17 am

### Re: Formal charge

More electronegative atoms can have a negative formal charge if you need to give them one.

Nathan Rothschild_2D
Posts: 131
Joined: Fri Aug 02, 2019 12:15 am

### Re: Formal charge

Get as many as you can to 0, and ensure that the center has a formal charge of 0.

mayarivers3I
Posts: 52
Joined: Wed Sep 18, 2019 12:18 am

### Re: Formal charge

It's fine to not have a formal charge of zero. The structure with the lowest energy would be the one where the formal charge is on the most electronegative element.

PriscillaLi_3G
Posts: 63
Joined: Fri Sep 27, 2019 12:30 am

### Re: Formal charge

Second best option is to get the formal charges of each atom as close to zero as possible. Give the negative formal charges to the atoms with higher electronegativity.

Sanjana Borle 2K
Posts: 111
Joined: Fri Aug 09, 2019 12:15 am

### Re: Formal charge

The second best option is to make sure that the more electronegative atom has a negative charge, and vice versa. this is considered the correct lewis structure.

005162902
Posts: 102
Joined: Wed Sep 18, 2019 12:15 am

### Re: Formal charge

If you can't get all the formal charges to zero, get as many as you can close to zero so that the Formal Charge of the molecule is as low as possible.That will be your most correct answer. It also helps to keep the charge off of the central atom. If the charge is on the outer molecules its easier for electrons to delocalize and show resonance.

Sofia Q
Posts: 49
Joined: Sat Aug 17, 2019 12:15 am

### Re: Formal charge

If all of them can't be 0, then you want them to be the smallest they can be, agreeing with any charge the compound hay have. A tip would be to keep the central 0 is possible, however.

EMurphy_2L
Posts: 128
Joined: Sat Sep 07, 2019 12:16 am

### Re: Formal charge

also, if the molecule has a charge (like CNO-) then the sum of all three charges should be that number

Tiffany Dong_4e
Posts: 51
Joined: Wed Sep 11, 2019 12:17 am

### Re: Formal charge

Getting close to 0 is ideal, but the "next best" option would be giving a more electronegative atom like oxygen a negative charge.