A new quantum chemical definition is proposed of the full atomic valence, V_A, taking into account both the covalent and ionic parts of the chemical bonds formed by atoms in molecules and crystals. The full atomic valencies, covalencies, and charges on atoms are calculated for nickel–oxygen crystalline compounds in the CNDO band theory approximation. A comparison of the chemical bonding in nickel and copper crystalline oxides is given. © 1994 John Wiley & Sons, Inc.