Explain the bond formation of hydrogen molecule.

Explanation

(i) Two hydrogen atoms `H_(a) and H_(b)` are separated by infinite distance. At this stage, there is no interaction between these two atoms and the potential energy of this system is arbitrarly taken as zero.
(ii) As these two atoms approach each other, in addition to electrostatic attractive forces between the nucleus and its own electrons, the following new forces begins to operate:

(iii) The new attractive forces (arrows) arise betwee : (a) nucleus of `H_(a)` and valence electron of `H_(b)`
(b) nucleus of `H_(b)` and the valence electron of `H_(a)`
(iv) The new repulsive forces ( arrows) arise between: (a) the nucleus of `H_(a) and H_(b)`
(b) the valence electrons of `H_(a) and H_(b)`
(v) The attractive forces tend to bring `H_(a) and H_(b)` together whereas the repulsive forces tenas to push them apart
(vi) At the initial stage, as the two hydrogen atoms approach each other, the attractive torces are stronger than repulsive forces and the potential energy deereases.
(vii) Astage +s reached where the net attractive forces are exactly balanced by repulsive forces and the potential energy of the system. acquires a minimum energy.
(viii) At this stage, there is a maximum overlap between the atomic orbitals of `H_(a) and H_(b)` and atoms `H_(a) and H_(b)` are now said to be bonded together by a covalent bond.