Question

Define catenation and illustrate with example.

Answer 1

Catenation is the property of an element to form bonds with other atoms of the same element, creating chains, branched structures, or ring structures. Compared to carbon, the elements of group 15 exhibit a far lesser tendency for catenation. In hydrazine (NH₂-NH₂), nitrogen forms a chain of two atoms, whereas in hydrazoic acid, it forms a chain of three atoms.

In the formation of several open-chain and cyclic compounds with multiple phosphorus atoms joined together, phosphorus exhibits a clear propensity for catenation. There is essentially no tendency for the other elements to catenate.

The following data makes it evident that the elements of group 15 have a lower tendency for catenation than carbon because of their significantly lower M-M bond energies.

Bond	C-C	N-N	P-P	As-As
Bond energy (kJ mol−1)	347.4	163.8	201.6	147.4