Explain the formation of $H_{2}$ molecule on the basis of Valence Bond Theory.

(N/A) Consider two hydrogen atoms $A$ and $B$ approaching each other, having nuclei $N_{A}$ and $N_{B}$, and electrons represented by $e_{A}$ and $e_{B}$.
When the two atoms are at a large distance from each other, there is no interaction between them. At this stage, the energy of the system is equal to the sum of the energies of both isolated $H$ atoms. In each atom, the nucleus and electron have an attractive interaction ($N_{A}-e_{A}$ and $N_{B}-e_{B}$).
When both atoms $H_{A}$ and $H_{B}$ approach each other, both attractive and repulsive forces are generated:
$(i)$ Attractive forces: These occur between the nucleus of one atom and its own electron ($N_{A}-e_{A}$, $N_{B}-e_{B}$) and between the nucleus of one atom and the electron of the other atom ($N_{A}-e_{B}$ and $N_{B}-e_{A}$).
$(ii)$ Repulsive forces: These occur between the electrons of the two atoms $(e_{A}-e_{B})$ and between the nuclei of the two atoms $(N_{A}-N_{B})$.
- Attractive forces pull the atoms toward each other, while repulsive forces push them apart.
- Experimental evidence shows that the magnitude of attractive forces is greater than that of repulsive forces. Consequently, the atoms move closer, and the potential energy of the system decreases.
$H_{2}$ formation: $(i)$ The atoms approach until the attractive and repulsive forces are balanced. $(ii)$ The system attains minimum potential energy. $(iii)$ At this stage, the two hydrogen atoms combine. $(iv)$ A stable hydrogen molecule is formed. $(v)$ The equilibrium bond length is $74 \ pm$.