Illustrated Glossary of Organic Chemistry

Formal charge: The charge on an atom in a Lewis structure if the bonding was perfectly covalent and the atom has exactly a half-share of the bonding electrons. (The difference between the number of electrons 'owned' by a covalently bonded atom versus the same atom without any bonds, i.e., a free atom of the same element.) Calculated using the formula FC = V - L - (C/2),  where: FC = formal charge, V = number of valence electrons for the atom as a free element, L = number of electrons in lone pairs, and C = number of electrons in covalent bonds.

Formal charge calculations for the zwitterionic form of glycine.