Electronegativity and molecular properties

The paradigm that the properties of the atoms determine the properties of the molecules that they form is systematically presented. To this end, three types of atomic properties are differentiated: a) those that can be determined directly by spectroscopy, b) those based on theoretical concepts, and c) those that can be assigned to the atoms interacting in molecules. On the basis of the electronega-tivity values of the atoms, which can be determined from spectroscopic data together with the assumption that the elec-tronegativities are equalized in bonds, partial charges of the atoms in molecules are determined. These partial charges are correlated with ESCA data and proton affinities. In addition, simple expressions are given for the reliable estimation of bond lengths, bond energies, and force constants.