oxydes

Oxides are chemical compounds that consist of oxygen combined with one or more elements. Binary oxides contain oxygen and a single other element, such as iron oxide (Fe2O3) or carbon dioxide (CO2). More complex oxides feature multiple metals or nonmetals in extended networks, including silicates and spinels.

Oxides are commonly categorized by the chemical behavior of the second element. Basic oxides form when metals react with oxygen and typically react with acids to produce salts and water (for example Na2O reacting with hydrochloric acid to yield NaCl and H2O). Acidic oxides are usually nonmetal oxides that react with bases to form salts and water (such as CO2 reacting with NaOH). Amphoteric oxides, such as Al2O3 and ZnO, can act as either acids or bases depending on the reacting partner.

In nature, oxides occur as minerals and rocks. Examples include hematite (Fe2O3), magnetite (Fe3O4), corundum (Al2O3), rutile (TiO2), and quartz (SiO2). They are major constituents of soils, magmatic rocks, and crustal materials, and they underpin a wide range of industrial substances.

Properties and applications of oxides vary widely. Many metal oxides are high-melting, refractory ceramics, while nonmetal oxides can be gases, liquids, or solids at room temperature. Oxides are central to cement and glass production, pigments, catalysts (for example TiO2 and V2O5), semiconductors (ZnO, SnO2), and magnetic materials (Fe3O4). Safety considerations include the potential irritation from oxide powders and the environmental role of oxide emissions in combustion processes.