Formal Charge

[Donna Nguyen 2L]

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

[Daniel Toscano 1L]

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]

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]

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]

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

[KBELTRAMI_1E]

try to calculate the lowest charges overall...

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

[KBELTRAMI_1E]

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]

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 :)