Chemical Bonding

The attractive force which holds various
constituents (atoms, ions, etc.) together in different
chemical species is called a chemical bond. Since the
formation of chemical compounds takes place as a result of
combination of atoms of various elements in different ways,
it raises many questions. Why do atoms combine? Why are
only certain combinations possible? Why do some atoms
combine while certain others do not? Why do molecules
possess definite shapes? To answer such questions different
theories and concepts have been put forward from time to time.

These are Kössel-Lewis approach, Valence Shell
Electron Pair Repulsion (VSEPR) Theory, Valence Bond (VB)
Theory and Molecular Orbital (MO) Theory. The evolution
of various theories of valence and the interpretation of
the nature of chemical bonds have closely been related to
the developments in the understanding of the structure
of atom, the electronic configuration of elements and the
periodic table. Every system tends to be more stable and
bonding is nature’s way of lowering the energy of the system
to attain stability.