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Croatica Chemica Acta, Vol.64 No.3 December 1991. -

The Periodic Table has been in its present form approximately 70 years and it remains the single most powerful means for organizing the electronic structure of matter and the principal agent for introducing chemical science to young students. Because of its vast exposure and familiarity, it has been treated as an icon and seldom examined critically. Nevertheless, everyone knows that energy is the governing parameter in determining the structure of molecules and solids and therefore it is surprising that some manifestation of atomic energy is not a part of it. Since the Periodic Table is made up of the valence electron configurations of ground state free atoms, the appropriate energies are the configuration energies and when these are added to complete the Table its misleading features are removed and its predominant role in ordering chemical phenomena is considerably enhanced.

Thus, such troublesome problems as: a why the chemistry of groups is not independent of row, b why all of the valence electrons in N, O, F, Cl and Br cannot be utilized in bonding, c the origin of the diagonal line separating metals from nonmetals and what determines its position, d why multiple bonding is more prevalent in the first row than in higher rows, are readily answered by the pattern and properties of configuration energies. The use of configuration energies also can be taken beyond the Periodic Table and applied to specific atoms in specific solids and molecules. Two methods of accomplishing this are described.

Autor: Leland C. Allen - ; Department of Chemistry, Princeton University, Princeton, NJ. 08544



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