VSEPR Theory - Lone Pairs

Sometimes the central atom will have more VSEP than are needed to make bonds to the outer atoms. The extra pairs of electrons on the central atom are called 'lone-pairs'.

Bond angles will deviate from their ideal values according to the rule that lone pairs repel other electrons more strongly than bonding pairs.

  • Although lone pairs are clearly smaller than atoms, they need to be closer to the nucleus of an atom than a bonding pair. Being closer to the central atom causes lone-pairs take up more of the available 'bonding space'.