Abstract:
The understanding of the mode of bonding in
different elements have begun in 1916 with the pioneering
contribution of G.N.Lewis [ 1 ] ;,.He propounded the
electronic theory of chemical bond by assuming that a
single bond forms due to sharing of two electrons parti-
cipating in the bond by two atoms. It was thus possible
to distinguish between various modes of bonding - ionic
bond, covalent bond co-ordinative bond etc. However,
these concepts faced formidable difficulties with the
advent of quantum mechanics. A molecule consists of an
ensemble of nuclei exerting mutually repulsive forces.
Their dispersion is prevented by the attractive forces
brought to-bear by the electrons. Any two nuclei are
always interacting with the entire electron cloud and it
is not permitted to associate two particular electrons
with a bond since the principle of indistinguishability
leads to an antisymmetric wave function and imposes on
all electrons the duty to play, on the average, the same
role. However, it is possible to translate some of the
classical concepts of bonding in terms of electron density
which has characteristic forms for different types of bonding.
