Hexavalents

Hexavalents refers to chemical species that exhibit a valence of six, or an oxidation state of +6. The term is applied to both elements in their hexavalent states and to the oxoanions and oxoacids formed in that state. In inorganic chemistry, +6 is a common high oxidation state for several elements and is associated with multiple oxo ligands and characteristic geometries.

Common hexavalent species include chromium in Cr(VI) compounds such as chromate (CrO4^2-) and dichromate (Cr2O7^2-); molybdenum in molybdate (MoO4^2-); tungsten in tungstate (WO4^2-); sulfur in sulfate (SO4^2-); and selenium in selenate (SeO4^2-). Many of these species adopt tetrahedral or distorted tetrahedral geometries around the central atom in solution or in solids; dichromate is often described as consisting of CrO4 units linked through shared oxygens.

Hexavalent species are typically strong oxidizing agents because the central atom is in a high oxidation state. They often exist as soluble oxoanions, and their reactivity is governed by redox chemistry with reducing agents. Health and environmental concerns are notable: several hexavalent chromium compounds are carcinogenic and tightly regulated in industry and waste management.

Applications and relevance include use as oxidants in synthesis, in pigments and coatings, and as reagents in inorganic chemistry. The study of hexavalent species emphasizes how oxidation state dictates structure, bonding, and reactivity in inorganic systems.