Page 1 of 1

### Formal Charge

Posted: Tue Nov 12, 2019 5:08 pm
How do you calculate formal charge? What's the equation and what does everything stand for?

### Re: Formal Charge

Posted: 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)

### Re: Formal Charge

Posted: 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.

### Re: Formal Charge

Posted: 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.

### Re: Formal Charge

Posted: 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

### Re: Formal Charge

Posted: 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)]

### Re: Formal Charge

Posted: 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

### Re: Formal Charge

Posted: 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 :)