In carbon monoxide (CO), carbon (C) has a triple covalent bond with oxygen (O). Two are normal covalent bonds, and the third is a coordinate covalent bond. Its Lewis structure is shown below.

Based on the formula for the formal charge, let us calculate the formal charge of CO. To do this, we must first calculate the formal charges on the individual atoms, C and O, and add them to find the net formal charge.

Carbon

V = 4, N = 2, B = 6

Therefore,

q_f = 4 – 2 – 6/2 = -1

Oxygen

V = 6, N = 2, B = 6

Therefore,

q_f = 6 – 2 – 6/2 = 1

The net formal charge is: -1 + 1 = 0

Therefore, the formal charge of carbon monoxide (CO) is zero.