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### Understanding Formal Charge

Posted: Sun Oct 25, 2015 12:20 am
I'm still a little confused about calculating the formal charge... Everyone keeps showing me a different method, but I think I'm just going to stick with what Lavelle showed in class. I know how to determine the valence electrons, but for the lone and shared pairs do I count each electron in the lone pair or count one pair as one. And do i count each bond as 1 or 2?

### Re: Understanding Formal Charge

Posted: Sun Oct 25, 2015 1:22 am
For both lone pairs and bonded electrons you count the electrons individually. For example, in a water molecule we know that oxygen has 2 lone pairs and 2 single bonds (1 single bond with each hydrogen). Using the formula given by Dr. Lavelle, $FC=V-(L+\frac{S}{2})$, we find that the formal charge of oxygen in a water molecule is 0. We find this by plugging in 4 for L since there are 4 electrons in 2 lone pairs, and 4 for S since there are 4 electrons in 2 single bonds.

$FC=6-(4+\frac{4}{2})=0$