Formal Charge Equation

[Yasmine Alameddine 2H]

Hi! In the past, I was taught how to calculate formal charge using the equation: FC=ve-(b+d)

ve: valence electrons
b: how many bonds are on the atom
d: how many dots surround the atom

Is using this equation okay, or should we be using FC=v-(L+s/2)?

[Jake Matsumoto 3E]

HI Yasmine! I think the equation you learned in the past is the same as the one we are currently using, as we are calculating the formal charge using the total number of shared electrons divided by 2 while you're simply using the number of bonds. There are 2 shared electrons to every surrounding bond, so the equations are giving us the same formal charge. Hope this helps.

[105717435]

A simpler way that I calculated formal charges is by subtracting the number of lines (bonds) - the number of each dot (each lone pair) from the total valence electrons. For example, O=C=O, Oxygen has 6 valence electrons -2 lines (bonds) - 4 dots (each lone pair dot) = 0 formal charge and then Carbon has 4 valence electrons- 4 lines- 0 dots= 0 formal charge.

[Lilia Hacoupian 2E]

Hello!

The best way I have learned to do it is (number of valence electrons) - (lone electrons) - (# of bonds). So for example we can use oxygen in the lewis structure of CO2. We know that oxygen has 6 valence electrons. There are also 2 lone pairs, so 4 lone electrons around a single oxygen. Finally, there is a double bond between the oxygen and the central carbon atom. So what we would do is subtract in the order 6-4-2=0 to determine that the formal charge of oxygen in the structure is zero. Hope this helps!

[CristinaG]

HI, I continue to use the first equation and have not run into any issues when completing the assignments