The number of carbon compounds already known at present is more than 5 million.

 Every day more new compounds are isolated or prepared in the laboratories.

 The two characteristics properties of carbon element which lead to the formation of a very large number of organic compounds are:

1. Catenation: The property of carbon element due to which its atom can join one another to form long carbon chains is called catenation.

A) Straight chain of carbon atoms

 B) Branched chain of carbon atoms

 C) Closed chain of carbon atoms

2.Tetravalency: Carbon has a valency of four so it is capable of bonding with four other atoms of carbon or atoms of some other mono-valent element.

Compounds of carbon are formed with oxygen, nitrogen, hydrogen, sulphur, chlorine and many other elements giving rise to compounds with specific properties which depend on the elements other than carbon present in the molecule.