• All organic compounds contain carbon atoms and most contain hydrogen atoms.
• The entire carbon atoms have four bonds. A stable carbon atom is said to be tetravalent.
• Other element may also be present. Any atom that is not carbon or hydrogen is called a heteroatom. Common heteroatoms include N, O, S, P and the halogens
• Some compounds have chain of atoms and some compounds have rings.

These features explain why there so many organic compounds: Carbon forms four strong bonds with itself and other elements. Carbon atoms combine together to form rings and chains.