Formal Charge


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Donna Nguyen 2L
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

Formal Charge

Postby Donna Nguyen 2L » Tue Nov 12, 2019 5:08 pm

How do you calculate formal charge? What's the equation and what does everything stand for?

Daniel Toscano 1L
Posts: 95
Joined: Tue Nov 13, 2018 12:18 am

Re: Formal Charge

Postby Daniel Toscano 1L » Tue Nov 12, 2019 5:23 pm

There are several equations you can use.
The one Lavelle showed us was: formal charge=valence electrons of atom-(lone pairs electrons +shared electrons/2) or FC=Ve-(L+S/2)
I personally like using: formal charge=valence electrons of atom-(bonds + dots) or FC=Ve-(B+D)

A Raab 1K
Posts: 56
Joined: Sat Aug 24, 2019 12:16 am

Re: Formal Charge

Postby A Raab 1K » Tue Nov 12, 2019 5:26 pm

Formal charge = V - (L - S/2)
V is valence electrons of the element
L is lone pairs the atom has
S is shared/bonding electrons
You want a formal charge of 0 on an atom as that is the most stable.

annikaying
Posts: 94
Joined: Sat Sep 14, 2019 12:16 am

Re: Formal Charge

Postby annikaying » Wed Nov 13, 2019 5:12 pm

formal charge = V - (L + B/2)
V - valence e
L - e in lone pairs
B - e in bonded pairs
This will give you the formal charge of one atom in a molecule. To find the formal charge add of the formal charges of all the individual atoms.

705198479
Posts: 55
Joined: Wed Sep 18, 2019 12:20 am

Re: Formal Charge

Postby 705198479 » Wed Nov 13, 2019 5:33 pm

when is will we know to calculate a formal charge, will it be noticeable in the question or are there key words

KBELTRAMI_1E
Posts: 108
Joined: Sat Jul 20, 2019 12:17 am

Re: Formal Charge

Postby KBELTRAMI_1E » Wed Nov 13, 2019 5:35 pm

try to calculate the lowest charges overall...

#of electrons in valence shell - [# of electrons in lone pairs + (# bonded electrons/2)]

KBELTRAMI_1E
Posts: 108
Joined: Sat Jul 20, 2019 12:17 am

Re: Formal Charge

Postby KBELTRAMI_1E » Wed Nov 13, 2019 5:36 pm

705198479 wrote:when is will we know to calculate a formal charge, will it be noticeable in the question or are there key words


do it when drawing lewis structures

Katherine Brenner 3H
Posts: 73
Joined: Wed Sep 18, 2019 12:18 am

Re: Formal Charge

Postby Katherine Brenner 3H » Fri Nov 15, 2019 7:51 pm

It is important to know that you will only be calculating the formal charge of one element at a time. I made this mistake for a while and it confused me :)


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