Enter the total number of valence electrons, lone pairs of electrons, and the total number of bound electrons to calculate the formal charge.

Formal Charge Formula

The following equation is used to calculate the formal charge of an atom. 

FC = V - ( LP +.5 * BE)
  • Where FC is the formal charge
  • V is the number of valence electrons
  • LP is the number of lone pair electrons
  • BE is the number of bound electrons

To calculate the formal change, divide the number of bound electrons by 2, add the number of lone pair electrons, then subtract this result from the number of valence electrons.

Formal Charge Definition

A formal charge is defined as the electrical charge of an individual atom.

Formal Charge Example

How to calculate a formal charge?

First, determine the number of valence electrons.

In this example, the valence electrons are found to be 3.

Next, determine the number of lone pair electrons.

in this case, the number of lone pair electrons is 1.

Next, determine the number of bound electrons.

For this problem, the number of bound electrons is 3.

Finally, calculate the formal charge using the formula above:

FC = V – ( LP +.5 * BE)

FC = 3 – ( 1 +.5 * 3)

FC = .5

FAQ

What is formal charge?

The formal charge is the electrical charge of an individual atom that is contained within a larger molecule.

How is formal charge calculated?

The formal charge is calculated using the valence, lone pair, and bound electrons of the atom to its surrounding molecule.