Quantum Mechanical Study of Some Atomic Properties

Abstract

Invoking the atomic radius as size descriptor, we can
easily predict and model so many physico chemical properties of
atoms and molecules. Since it has not been possible to isolate an
atom and to determineits size, the atomic size is not an observable.
The theoretical paradigm to study the electronic structureand
properties of atoms, molecules and crystalline bodies is quantum
mechanics or wave mechanics. But, radius is not a quantum
mechanical observable and cannot be evaluated easily. As we know
that atomic radius is periodic in nature, we can compute the absolute
size of atom invoking its periodic correlation with other periodic
properties. Recently Chakraborty et al. published a new set of
theoretical atomic radii on basis of other periodic properties namely
effective nuclear charge and ionization energy. In this venture , we
have used that particular atomic size to calculate another important
periodic parameter namely global hardness (η). Using the inverse
relationship between atomic size and global hardness, we have
computed a set of atomic hardness for 103 elements of the periodic
table. The express periodicity of periods and groups exhibited by
the computed atomic hardness and the manifest relativistic effect of
the lanthanoids and actinoids, etc. speak volumes for the efficacy of
the present method. We have also applied our computed atomic
hardness to evaluate another important periodic parameter,
electrophilicity index (ω).The absolute electronegativity value
evaluated by Chakraborty et al. is the necessary input to compute
the electrophilicity index .A comparative study has been done with
our computed electrophilicity index values with other reported
results. A nice correlation supports the validity of this work.