Selenide
Encyclopedia
A selenide is a chemical compound in which selenium
serves as an anion with oxidation number
of −2 (Se2−), much as sulfur
does in a sulfide
. The chemistry of the selenides and sulfides are similar.
Similar to sulfide
, for an aqueous solution
, selenide ion, Se2−, is prevalent only in very basic conditions. In neutral conditions, hydrogen selenide ion
, HSe−, is most common. In acid conditions, hydrogen selenide
, H2Se, is formed.
Some selenides are reactive to oxidation by air. Owing to the greater reducing power of selenide, metal selenides are more easily decomposed to the elements than are sulfide
s (tellurides
are even more labile). Selenides of electropositive metals: such as aluminium selenide readily hydrolyse, even in moist air, evolving toxic hydrogen selenide gas.
Pure selenide mineral
s are rare, instead selenium tends to partially substitute for sulfide in many sulfide mineral
s, although the degree of substitution is only of commercial interest for copper sulfide ores. Selenium is thus recovered as a by-product of copper mining. Some selenide minerals include ferroselite
and umangite
.
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
serves as an anion with oxidation number
Oxidation number
In coordination chemistry, the oxidation number of a central atom in a coordination compound is the charge that it would have if all the ligands were removed along with the electron pairs that were shared with the central atom. Oxidation numbers are often confused with oxidation states.The...
of −2 (Se2−), much as sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
does in a sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
. The chemistry of the selenides and sulfides are similar.
Similar to sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
, for an aqueous solution
Aqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
, selenide ion, Se2−, is prevalent only in very basic conditions. In neutral conditions, hydrogen selenide ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
, HSe−, is most common. In acid conditions, hydrogen selenide
Hydrogen selenide
Hydrogen selenide is the inorganic compound with the formula H2Se. It is the simplest and virtually the only hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit: 0.05 ppm over an 8 hour period...
, H2Se, is formed.
Some selenides are reactive to oxidation by air. Owing to the greater reducing power of selenide, metal selenides are more easily decomposed to the elements than are sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
s (tellurides
Telluride (chemistry)
The telluride ion is Te2−. It is the final stable member of the series of dianions O2−, S2−, and Se2− ....
are even more labile). Selenides of electropositive metals: such as aluminium selenide readily hydrolyse, even in moist air, evolving toxic hydrogen selenide gas.
Pure selenide mineral
Selenide mineral
Selenide minerals are those minerals that have the selenide anion as a main component.Selenides are similar to sulfides and often grouped with them.Examples include:* athabascaite Cu5Se4* clausthalite PbSe* penroseite Se2* stilleite ZnSe...
s are rare, instead selenium tends to partially substitute for sulfide in many sulfide mineral
Sulfide mineral
The sulfide minerals are a class of minerals containing sulfide as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts...
s, although the degree of substitution is only of commercial interest for copper sulfide ores. Selenium is thus recovered as a by-product of copper mining. Some selenide minerals include ferroselite
Ferroselite
Ferroselite is an iron selenide of general formula FeSe2 precipitated under reducing conditions in anoxic environments. It is a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits....
and umangite
Umangite
Umangite is a copper selenide mineral, Cu3Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with a black streak. It has a metallic luster.Umangite is...
.
Examples
- Gallium(II) selenideGallium(II) selenideGallium selenide is a chemical compound. It has a hexagonal layer structure, similar to that of GaS. It is a photoconductor, a second harmonic generation crystal in nonlinear optics, and has been used as a far-infrared conversion material at 14-31 THz and above.-Uses:It is said to have potential...
- Indium(III) selenideIndium(III) selenideIndium selenide is a compound of indium and selenium. It has potential for use in photovoltaic devices and it has been the subject of extensive research. The two most common forms α- and β- have defect wurtzite structures, however there are five known forms The α- β phase transition is...
- Sodium selenideSodium selenideSodium selenide is a inorganic compound of sodium and selenium with the chemical formula Na2Se. This colourless solid is prepared by the reaction of selenium with a solution of sodium in ammonia....
, Na2Se - Cadmium selenideCadmium selenideCadmium selenide is a solid, binary compound of cadmium and selenium. Common names for this compound are cadmium selenide, cadmium selenide, and cadmoselite ....