Aluminium selenide is the inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 Al

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

₂Se

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...

₃.

It is a solid prepared by igniting a mixture of the elements:

2 Al + 3 Se → Al₂Se₃

The pure compound is white, but typical samples are coloured. Samples of aluminium selenide must be protected from moisture, because the compound hydrolyzes readily, giving off highly toxic hydrogen selenide gas:

Al₂Se₃ + 3 H₂O → Al₂O₃ + 3 H₂Se

Al₂Se₃ has been used as a precursor to 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...

, which is released when the solid is treated with acids.

Safety

Aluminium selenide should be stored and handled away from moisture and air.