Q.What do you understand by catenation?

Catenation is an element's ability to bond with itself, building up extended chains (or rings) of atoms. For an element to catenate strongly, four conditions must all be met: its valency must be at least two; it must be able to bond to itself; that self-bond must be roughly as strong as its bond to other elements; and the resulting catenated compound must be kinetically inert -- stable enough not to fall apart on contact with other molecules.

Carbon meets all four conditions better than any other element in the periodic table, which is the structural root of the entire discipline of organic chemistry: carbon builds an essentially unlimited range of compounds from chains and rings of carbon atoms, bonded both to itself and to other elements such as hydrogen, oxygen, nitrogen, sulphur and the halogens. This catenating ability then collapses sharply on descending group 14: silicon and germanium catenate only weakly com …