Oksiidide

Oksiidide are a broad class of chemical compounds composed of oxygen atoms bonded to one or more other elements. In most oxides, oxygen exists as oxide ions (O2−) and combines with elements across the periodic table, yielding a wide range of stoichiometries and structures. Oxides are among the most common inorganic substances in nature and in industrial materials, and they play key roles in geology, ceramics, catalysis, and electronics.

Classification and types

Oxides are often categorized by the nature of the bonding and the metal–oxygen interaction. Metal oxides tend to be basic and react with acids to form salts and water; nonmetal oxides tend to be acidic and react with bases to form salts and water. Some oxides are amphoteric, able to react with both acids and bases. The class also includes peroxides (containing O2^2−) and superoxides (O2− in a different coordination). Minerally, oxides include ferric oxides (such as Fe2O3), ferrous oxides (FeO), and mixed oxides like spinels (e.g., MgAl2O4) and titanates.

Occurrence and applications

Oxides occur widely in rocks and soils, as well as in modern materials. Common oxides include silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxides (Fe2O3, Fe3O4), titanium dioxide (TiO2), and zinc oxide (ZnO). Industrially important uses include cement production (CaO), pigments (Fe2O3 for red hues, TiO2 for white), ceramic glazes, catalysis (V2O5, MoO3), and semiconductor/nanomaterials (ZnO, TiO2, SnO2). Their properties—melting points, band gaps, and reactivity—can be tailored through composition, crystallinity, and particle size.

Synthesis and handling

Oxides form by oxidation of elements, roasting of minerals, or dehydration of hydroxides. They may require specific atmospheres to achieve desired oxidation states. Safety varies by oxide; some are relatively inert, while others can be abrasive, toxic, or reactive under heat or in acids.