Inorganic compound

Chemical compounds generally lacking carbon–hydrogen bonds; includes salts, oxides, metals, coordination compounds and some carbon-containing exceptions. Covers properties, classes, history and uses.

An inorganic compound is commonly defined as a chemical compound that does not contain carbon–hydrogen (C–H) bonds. In practical terms this distinguishes most inorganic substances from conventional organic molecules. For a concise definition, the absence of C–H groups is the usual rule, though the boundary with carbon-containing species can be blurred.

Structurally, inorganic compounds show great variety. They range from simple diatomic molecules and covalent oxides to ionic salts with extended crystal lattices, metallic alloys and coordination complexes with central metal atoms. Electronic properties vary widely: some are electrical insulators, others are conductive metals or ionic electrolytes, and many serve as semiconductors or catalysts.

Common classes

Salts — ionic compounds such as sodium chloride (NaCl) formed from acids and bases.
Oxides — compounds of oxygen with metals or nonmetals, from silica (SiO2) to iron oxides.
Halides, sulfides and nitrides — anions bonded to metals or covalent frameworks.
Acids and bases — mineral acids like sulfuric acid and inorganic bases like sodium hydroxide.
Coordination and organometallic compounds — complexes where ligands bind to central metals; these bridge inorganic and organic chemistry.

Historically, inorganic chemistry grew from mineralogy and the study of nonliving matter. During the 18th and 19th centuries systematic analysis and classification expanded as industry demanded materials such as sulfuric acid, salts and metal alloys. The field now overlaps with materials science, solid-state chemistry and catalysis.

Uses and importance

Fertilizers and agrochemicals (nitrates, phosphates).
Catalysts and industrial reagents (metal oxides and complexes).
Materials: ceramics, glass, pigments, batteries and semiconductors.
Environmental and biological roles — metal ions and inorganic cofactors are essential in many enzymes and processes.

Distinctions matter: some carbon-containing substances such as carbonates, carbides, cyanides and carbon oxides are usually treated as inorganic despite containing carbon, while true organic chemistry focuses on molecules with C–H frameworks. The intermediate area of organometallic chemistry further blurs these categories. For more on related terms see organic compound and the concept of carbon-based classification.