text: The bond valence method is a development of Paulings rules. In 1930, Lawrence Bragg showed that Paulings electrostatic valence rule could be represented  by electrostatic lines of force emanating from cations in proportion to the cation charge and ending on anions. The lines of force are divided equally between the bonds to the corners of the coordination polyhedron.
  Starting with Pauling in 1947 a correlation between cation–anion bond length and bond strength was noted. It was shown later that if bond lengths were included in the calculation of bond strength, its accuracy was improved, and this revised method of calculation was termed the bond valence. These new insights were developed by later workers culminating in the set of rules termed the bond valence model.