Semiempirical Evaluation of the Global Hardness of the Atoms of 103 Elements of the Periodic Table Using the Most Probable Radii as their Size Descriptors

Relying upon the fact that the density functional computation of the global hardness of the atoms of the elements are still at large and there is some mathematical in congruency between the theory and operational formula of finite difference approximation, we have suggested a radial-dependent ansatz for evaluating global hardness of atoms as: eta = a(7.2/r) + b (in eV), where, "a" and "b" are the constants and r is the absolute radius of atoms in angstrom unit. The ansatz is invoked to evaluate the global hardness of atoms of 103 element of the periodic table. The evaluated new set of global hardness is found to satisfy the sine qua non of a reasonable scale of hardness by exhibiting perfect periodicity of periods and groups and correlating the gross physicochemical properties of elements. The inertness of Hg and extreme reactivity Cs atoms are nicely correlated. The chemical reactivity and its variation in small steps in the series of lanthanide elements are also nicely reproduced. The results of the present semiempirical calculation also have strong correlation with the result of some sophisticated DFT calculation for a set of atoms. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 1206-1213, 2010