SiO3

SiO3 is a chemical formula that can refer to more than one silicon–oxygen species, and its meaning depends on the chemical context. The most common reference is to the metasilicate units found in silicate chemistry, where SiO3^2− denotes a silicate building block that forms part of larger networks in minerals and in industrial silicate salts. In solution and in solid silicate materials, silicon is typically in the +4 oxidation state and is bonded to oxygen in a tetrahedral arrangement, with the SiO3 unit linking into chains, sheets, or three‑dimensional frameworks through shared oxygen atoms.

In practical terms, metasilicate species occur in salts such as sodium metasilicate (Na2SiO3) and related minerals. These materials are important in industry as water glass, cement additives, detergents, and binders. In natural settings, metasilicate units are found in minerals like wollastonite (CaSiO3), where SiO3 units connect to form crystalline silicate structures. The broader silicate chemistry encompasses a wide range of polymerization levels, from isolated SiO4 tetrahedra to extensive frameworks, with the SiO3 unit appearing in chain and sheet silicates.

SiO3 also has limited relevance as a neutral, discrete molecule. A stable, isolable silicon trioxide (SiO3) does not exist under ordinary conditions; silicon prefers oxidation states and oxide forms that lead to SiO2 or to silicate networks rather than a standalone SiO3 molecule. In aqueous systems, metasilicate can hydrolyze and condense, linking into larger silicate networks and ultimately contributing to siliceous materials.

Summary: SiO3 most often denotes the metasilicate unit in silicate chemistry and related salts, while a stable neutral SiO3 molecule is not known.