The unique property of carbon that allows it to form so many compounds is catenation — the ability of carbon atoms to bond with one another to form long chains, branched structures, and rings.
This is possible because:
- Tetravalency – Carbon has four valence electrons, so it can form up to four covalent bonds with other atoms (including other carbons).
- Strong C–C bonds – Carbon–carbon bonds are strong and stable, which allows long chains and complex molecules to exist.
- Bond variety – Carbon can form single, double, and triple covalent bonds, further increasing structural diversity.
- Bonding with many elements – Carbon readily bonds with hydrogen, oxygen, nitrogen, sulfur, halogens, and many other elements, creating countless possibilities.
Because of these features, carbon forms the backbone of organic chemistry, giving rise to millions of different compounds.