According to the Valence Shell Electron Pair Repulsion (VSEPR) theory, lone pairs of electrons are localised on the central atom, whereas bonding pairs are shared between two atoms. As a result, lone pair electrons occupy more space and cause greater repulsion than bonding pairs. Therefore, the repulsive interaction of electron pairs decreases in the order: lone pair-lone pair (lp-lp) > lone pair-bond pair (lp-bp) > bond pair-bond pair (bp-bp) .