chemistry

FORMAL CHARGE

Formal charge is a factor based on a pure covalent bond formed by the sharing of electron pairs equally by neighbouring atoms . Formal charge may be regarded as the charge that an atom in a molecule would have if all the atoms had the same electronegativity.

It may or may not approximate the real ionic charge. In case of a polyatomic ions, the net charge is possessed the real ion as a whole and not by an particular atom. It is, however, feasible to assign a formal charge on an atom in a polyatomic molecule or ion.

Where	Qf  = [ N A − N M ]= [ N A − N LP   − 1/ 2NBP ]

N_A= number of electrons in the valence shell in the free atom

N_M= number of electrons belonging to the atom in the molecule