Heteroatoms, such as oxygen, nitrogen, sulfur, or halogens, replace hydrogen atoms in a hydrocarbon chain within functional groups. These heteroatoms introduce different chemical properties and reactivities into the molecule, contributing to the diversity of organic compounds.

Some common functional groups include hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), amino (-NH2), and sulfhydryl (-SH) groups, among others.

Compounds containing carbon are exceptionally stable due to the strong bonds carbon forms with most other elements, making them resistant to decomposition.

Carbon can form compounds with oxygen, hydrogen, nitrogen, sulfur, chlorine, and many other elements.

The valency of carbon is four, allowing it to form bonds with four other atoms of carbon or other mono-valent elements.