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Formal charge

Posted: Sun Nov 03, 2019 11:27 pm
by Andrea_1H
What if we can’t get all the atoms to have a formal charge of 0? Is there a “second best” option?

Re: Formal charge

Posted: Sun Nov 03, 2019 11:34 pm
by Sidharth D 1E
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.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:36 pm
by Maya Serota 3G
You just want to get as close to 0 as possible.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:37 pm
by Eesha Sohail 1D
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.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:39 pm
by Sanjana K - 2F
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.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:43 pm
by SVajragiri_1C
Just make sure the formal charges are as close to 0 as possible.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:47 pm
by quresh3E
The added formal charges of the atoms should be zero. With whatever negative formal charges being on the most electronegative atom.

Re: Formal charge

Posted: Sun Nov 03, 2019 11:50 pm
by jmtz1I
The best thing is to have a formal charge of 0, but if not my TA stated to find the lowest possible charge.

Re: Formal charge

Posted: Sun Nov 10, 2019 8:18 pm
by Abigail_Hagen2G
More electronegative atoms can have a negative formal charge if you need to give them one.

Re: Formal charge

Posted: Sun Nov 10, 2019 11:45 pm
by Nathan Rothschild_2D
Get as many as you can to 0, and ensure that the center has a formal charge of 0.

Re: Formal charge

Posted: Mon Nov 11, 2019 5:03 pm
by mayarivers3I
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.

Re: Formal charge

Posted: Mon Nov 11, 2019 5:06 pm
by PriscillaLi_3G
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.

Re: Formal charge

Posted: Mon Nov 11, 2019 6:39 pm
by Sanjana Borle 2K
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.

Re: Formal charge

Posted: Mon Nov 11, 2019 7:03 pm
by 005162902
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.

Re: Formal charge

Posted: Mon Nov 11, 2019 7:24 pm
by Sofia Q
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.

Re: Formal charge

Posted: Mon Nov 11, 2019 10:03 pm
by EMurphy_2L
also, if the molecule has a charge (like CNO-) then the sum of all three charges should be that number

Re: Formal charge

Posted: Mon Nov 11, 2019 10:24 pm
by Tiffany Dong_4e
Getting close to 0 is ideal, but the "next best" option would be giving a more electronegative atom like oxygen a negative charge.