Uranous is the

chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...

term for the reduced tetrapositive

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

that exhibits the valence U⁴⁺. It is one of the two common ionic states of uranium found in nature, the other being the

oxidised Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

hexapositive ion called

uranyl The uranyl ion is an oxycation of uranium in the oxidation state +6, with the chemical formula . It has a linear structure with short U–O bonds, indicative of the presence of multiple bonds between uranium and oxygen. Four or more ligands may ...

. Uranous compounds are usually unstable; they revert to the oxidised form on exposure to air. Examples of these compounds include

uranium tetrachloride Uranium tetrachloride is an inorganic compound, a salt of uranium and chlorine, with the formula UCl4. It is a hygroscopic olive-green solid. It was used in the electromagnetic isotope separation (EMIS) process of uranium enrichment. It is one o ...

() and

uranium tetrafluoride Uranium tetrafluoride is the inorganic compound with the formula UF4. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent (uranous) state is important in various technological processe ...

(), which are important in

molten salt reactor A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States. The 1950's Ai ...

applications, and

uranium dioxide Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear rea ...

(), a common form of

nuclear fuel Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing ...

. The solvated ion is normally not present in water. Most of the compounds like are better described with the

covalent bond A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms ...

than an

ionic bond Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, and is the primary interaction occurring in ionic compounds. ...

. Minerals containing the uranous

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

are more subdued in colour, typically brown or black, and occur in reducing environments. Common uranous minerals include

uraninite Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes t ...

and

coffinite Coffinite is a uranium-bearing silicate mineral with formula: U(SiO4)1−x(OH)4x. It occurs as black incrustations, dark to pale-brown in thin section. It has a grayish-black streak. It has a brittle to conchoidal fracture. The hardness of coffini ...

References

{{reflist Cations Uranium(IV) compounds Uranium compounds