Arsenide is an arsenic

Arsenic

Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

 anion with the charge −3. The trianion is formed by the reduction of arsenic by three electrons. For example heating arsenic powder with excess sodium gives sodium arsenide (Na₃As). The anions have no existence in solution since they are extremely basic. These solid salts have very high lattice energies

Lattice energy

The lattice energy of an ionic solid is a measure of the strength of bonds in that ionic compound. It is usually defined as the enthalpy of formation of the ionic compound from gaseous ions and as such is invariably exothermic. Lattice energy may also be defined as the energy required to completely...

.

An arsenide (compound) is a compound with arsenic in oxidation state

Oxidation state

In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

 −3, but the term is used loosely. The mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 sperrylite

Sperrylite

Sperrylite is a platinum arsenide mineral with formula: PtAs2 and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits...

 (PtAs₂) is called a platinum arsenide, but the formal oxidation state for arsenic is −2. because the solid is usually described as Pt⁴⁺,As₂^4-. The description of gallium arsenide (GaAs) is more straightforward since it features isolated arsenic centers.

Arsenides are toxic because of the inherent toxicity of arsenic and all of its compounds.

Metal arsenides react with acids to form highly toxic arsine

Arsine

Arsine is the chemical compound with the formula AsH3. This flammable, pyrophoric, and highly toxic gas is one of the simplest compounds of arsenic...

 gas.

See category for a list.