Catenation is the ability of an element to form bonds with other atoms of the same element. It is exhibited by both carbon and silicon. The ability of catenation in carbon is greater than in silicon, as carbon atoms are smaller than silicon atoms. Hence, the nucleus of carbon exerts a greater force of attraction on the shared pair of electrons, and holds them firmly to form strong covalent bonds. This is also the reason behind the ability of carbon to hold n number of atoms (form lengthy compounds). On the other hand, silicon can only hold seven or eight atoms to form weaker covalent bonds.