(a) A covalent bond is formed by the partial overlap of two half-filled atomic orbitals of two atoms.
(b) Greater the overlapping of atomic orbitals between the atoms, stronger the covalent bond formed.
(c) When a covalent bond is formed, the energy of the molecule decreases and the molecule becomes more stable.
(d) The extent of overlapping of orbitals follows the following order. s-s overlapping < s-p overlapping < p-p overlapping.
(e) Overlapping along the axis is stronger than the overlapping on sideways.