Formal Charge Cancellation

$FC=V-(L+\frac{S}{2})$

Malik Oda 1F
Posts: 51
Joined: Thu Jul 25, 2019 12:15 am

Formal Charge Cancellation

In what situations is it ok to cancel out formal charges?

205296774
Posts: 66
Joined: Thu Jul 25, 2019 12:15 am

Re: Formal Charge Cancellation

Sometimes, because of the octet rule or combination of atoms, it isn't possible for each atom to have a formal charge of zero, but if the overall formal charge is zero then make sure that the charges on the atoms sum to the overall charge. For example, if one atom as a plus 1 and another has a minus one, that sums to a total of zero which is correct. This is the instance when you would "cancel" the charges. Ideally, you want each atom to have no charge, but that is not always possible. Just ensure that what you draw is the most stable and that it sums to the overall charge.

Hope this helps!

Aliya Jain 2B
Posts: 101
Joined: Wed Sep 11, 2019 12:16 am

Re: Formal Charge Cancellation

Formal charge should be considered after the octet rule is observed in most cases!

Manav Govil 1B
Posts: 104
Joined: Sat Sep 07, 2019 12:19 am

Re: Formal Charge Cancellation

Exactly. Look at CO for example. The lewis structure would indicate a triple bond between the two atoms. If we are to fill the octet correctly, the final formal charge for Oxygen is +1 and the final formal charge for Carbon is -1. These two cancel out to 0, which is the overall charge of the molecule.