heteroatoms

Heteroatoms are atoms in organic compounds other than carbon and hydrogen. They include oxygen, nitrogen, sulfur, phosphorus, and the halogens (fluorine, chlorine, bromine, iodine), though some contexts consider other non-carbon atoms as heteroatoms. Their presence differentiates organic molecules from simple hydrocarbons by introducing polarity, reactivity, and sites for chemical bonding beyond C–C and C–H.

Common roles of heteroatoms include forming functional groups such as hydroxyl (O–H), carbonyl (C=O), amino (–NH2), amide (–CONH–), phosphate (–PO4^3–), sulfonyl (–SO2–), and halide (–X). Their electronegativity and lone pairs enable hydrogen bonding, acid–base chemistry, nucleophilic or electrophilic reactions, and coordination to metals in catalysis or bioinorganic systems.

In biochemistry, heteroatoms are essential for structure and function. Oxygen, nitrogen, and phosphorus appear in nucleic acids, proteins, carbohydrates, and lipids; their ability to donate or accept electrons underpins enzyme activity, molecular recognition, and energy transfer. The presence and position of heteroatoms influence solubility, polarity, and conformational preferences.

In materials chemistry, heteroatom doping or incorporation modifies electronic, optical, and catalytic properties of polymers, glasses, and inorganic frameworks. Heteroatoms in heterocycles—the ring systems that contain non-carbon atoms—play a central role in medicinal chemistry and natural product design.