The property of element due to which it forms covalent bonds with other atoms of the same element to form a chain of atoms is called catenation.
Carbon has a unique nature in that it is able to catenate and form millions of organic compounds. Carbon shows the property of catenation to the maximum extent. Apart from carbon sulphur, silicon etc also show this property to some extent.
Carbon may form bonds with other atoms of carbon. This carbon property is known as catenation, carbon can form a long chain due to catenation; thus bonding with other carbon atoms. By catenation, carbon can produce single, double and triple bonds.
Examples are sulphur show catenation up to eight atoms in the formation of S8 molecules of sulphur. It also shows catenation in polysulphide ions Sn2-, Sulphanes H-Sn-H and polysulfuric acid HO2S-Sn-SO3H.