uranous

Uranous is a historical term in inorganic chemistry for uranium in the +4 oxidation state, designated U4+ or U(IV). The corresponding higher oxidation state, +6, is typically referred to as uranic.

Uranous compounds are typically reducing relative to uranyl (U(VI)). In aqueous solution, U4+ is readily oxidized by air or oxidants to UO2^2+ (uranyl) species. Because of hydrolysis, aqueous uranium(IV) forms polymeric and hydroxo complexes, and its salts are often sparingly soluble. Common uranium(IV) salts include uranium(IV) chloride (UCl4) and uranium(IV) sulfate (U(SO4)2). The color of uranous compounds varies with ligands; many are pale green to colorless in solution; solid compounds may appear white, gray, or greenish.

Natural occurrence: In minerals, uranium can exist as UO2 in uraninite, where uranium is in the +4 oxidation state. In oxidizing environments, uranium is typically found as uranyl (UO2^2+; +6). The term uranous is chiefly used in older texts; modern nomenclature tends to specify oxidation states as U4+ or uranium(IV).

Safety: Uranium compounds are radioactive and chemically toxic; handling requires appropriate precautions and regulatory compliance.