Formal charge question

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longjump
Posts: 29
Joined: Fri Sep 28, 2018 12:17 am

Formal charge question

Postby longjump » Tue Nov 06, 2018 9:19 pm

Is formal charge the best way to see if your lewis diagram is in the most likely arrangement, or is there another way to tell?

Rian Montagh 2K
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: Formal charge question

Postby Rian Montagh 2K » Tue Nov 06, 2018 10:27 pm

For me, I go by number of electrons, least electronegative at the center, and symmetry before I look at formal charge. Formal charge is the main criteria I use after getting the basic structure.

Catherine Kim 3K
Posts: 31
Joined: Fri Sep 28, 2018 12:26 am

Re: Formal charge question

Postby Catherine Kim 3K » Wed Nov 07, 2018 5:36 pm

To see if your Lewis Diagram is the most likely arrangement is to first make sure you follow all the steps.
1. Count total number of valence electrons on molecule.
2. Draw single bonds between atoms.
3. Count how many electrons remain and assign them as lone pairs to fill valence shell.
4. If there are unfilled valence orbitals, share the lone pairs to fill the valence orbitals.
5. If there is more than one possible structure, then we consider all to resonance structure.
6. Minimize the formal charges on all atoms.

So formal charge is usually the last step, but make sure to check if your lewis structure follows the exceptions too.

shaunajava2e
Posts: 66
Joined: Fri Sep 28, 2018 12:26 am

Re: Formal charge question

Postby shaunajava2e » Thu Nov 08, 2018 11:36 am

if you have accounted for all the electrons and checked for everything else (like stated above,) yes, formal charge is a great way double check that your structure is in the most stable form.

Jasmine Chow 1F
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Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 1 time

Re: Formal charge question

Postby Jasmine Chow 1F » Thu Nov 08, 2018 2:48 pm

Once I see every element has its respective electrons and all the needed bond have been inserted I use the formal charge to solidify the lewis structure is in its most stable form. Its a great way to check your work.

Zubair Ahmed 1L
Posts: 81
Joined: Fri Sep 28, 2018 12:16 am

Re: Formal charge question

Postby Zubair Ahmed 1L » Thu Nov 08, 2018 5:03 pm

When I draw out Lewis structures, I count all the numbers of valence electrons in the given molecule and follow the octet guidelines given to us by Dr. Lavelle. I calculate formal charge when I need to draw out the lowest energy Lewis structure.

Hannah Yates 1K
Posts: 59
Joined: Fri Sep 28, 2018 12:27 am

Re: Formal charge question

Postby Hannah Yates 1K » Fri Nov 09, 2018 3:35 pm

Formal charge is usually what I check last. It’s a good way to check that you didn’t do something completely wrong because if you had a formal charge of like -4 somewhere, thats a big clue that there is a big mistake.
If the formal charges all make sense and are where they should be (negative on most electronegative atom), then your structure is most likely correct.

Phoebe Chen 4I
Posts: 55
Joined: Fri Sep 28, 2018 12:29 am

Re: Formal charge question

Postby Phoebe Chen 4I » Fri Nov 09, 2018 3:41 pm

Formal charge is the best way to tell if you have the most stable lewis structure. I don't know of any other way. With the formal charges, you want to get each of them as close to zero as possible and you want to make sure that all of them add up to zero.

Karla_Ocampo 4E
Posts: 32
Joined: Tue Nov 21, 2017 3:01 am

Re: Formal charge question

Postby Karla_Ocampo 4E » Fri Nov 09, 2018 5:13 pm

Hi! Yes I think that by determining the formal charge we are able to know and keep track of the electrons and thus it is important for predicting the reactivity. I think it is the best way to know if you have the most stable lewis structure.

Danny Zhang 4L
Posts: 62
Joined: Fri Sep 28, 2018 12:26 am

Re: Formal charge question

Postby Danny Zhang 4L » Sat Nov 10, 2018 6:41 pm

For all of the Lewis structure questions I've done so far, I have only aimed for 0 formal charges for the most stable structure. If it was a polyatomic/monatomic ion, then I aim for one atom having the indicated charge.


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