• The covalent bond is formed by overlapping of those orbital which contains impaired electrons.
• When the overlapping is along axis, the overlapping becomes maximum and strong, called as o sigma bond.
• During overlapping, the electron present in the valance orbit must have opposite spin.
• Covalent molecule have lower energy than combining atoms.
Therefore resulting molecule are always stable.
The extent of overlapping is ss > s-p > p-p.
