Formal charge


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

Formal charge

Postby Andrea_1H » Sun Nov 03, 2019 11:27 pm

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: 62
Joined: Sat Aug 24, 2019 12:17 am

Re: Formal charge

Postby Sidharth D 1E » Sun Nov 03, 2019 11:34 pm

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

Postby Maya Serota 3G » Sun Nov 03, 2019 11:36 pm

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

Eesha Sohail 1D
Posts: 65
Joined: Sat Aug 17, 2019 12:16 am

Re: Formal charge

Postby Eesha Sohail 1D » Sun Nov 03, 2019 11:37 pm

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: 71
Joined: Sat Sep 07, 2019 12:17 am

Re: Formal charge

Postby Sanjana K - 2F » Sun Nov 03, 2019 11:39 pm

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_1G
Posts: 64
Joined: Thu Jul 11, 2019 12:16 am

Re: Formal charge

Postby SVajragiri_1G » Sun Nov 03, 2019 11:43 pm

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

Postby quresh3E » Sun Nov 03, 2019 11:47 pm

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

jmtz1I
Posts: 30
Joined: Wed Sep 18, 2019 12:15 am

Re: Formal charge

Postby jmtz1I » Sun Nov 03, 2019 11:50 pm

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: 67
Joined: Fri Aug 09, 2019 12:17 am

Re: Formal charge

Postby Abigail_Hagen2G » Sun Nov 10, 2019 8:18 pm

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

Nathan Rothschild_2D
Posts: 79
Joined: Fri Aug 02, 2019 12:15 am

Re: Formal charge

Postby Nathan Rothschild_2D » Sun Nov 10, 2019 11:45 pm

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

Postby mayarivers3I » Mon Nov 11, 2019 5:03 pm

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

Postby PriscillaLi_3G » Mon Nov 11, 2019 5:06 pm

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: 73
Joined: Fri Aug 09, 2019 12:15 am

Re: Formal charge

Postby Sanjana Borle 2K » Mon Nov 11, 2019 6:39 pm

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: 58
Joined: Wed Sep 18, 2019 12:15 am

Re: Formal charge

Postby 005162902 » Mon Nov 11, 2019 7:03 pm

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

Postby Sofia Q » Mon Nov 11, 2019 7:24 pm

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: 84
Joined: Sat Sep 07, 2019 12:16 am

Re: Formal charge

Postby EMurphy_2L » Mon Nov 11, 2019 10:03 pm

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

Postby Tiffany Dong_4e » Mon Nov 11, 2019 10:24 pm

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


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