Overview

In chemistry, "arsenide" most commonly denotes the anion As3− or compounds in which arsenic formally has a −3 oxidation state. The simple ionic form, often called the arsenide ion, contrasts with molecular arsenic species and with oxidized forms such as arsenite and arsenate. Many materials described as arsenides are extended solids or intermetallic phases rather than discrete As3− salts.

Composition and oxidation state

Arsenic in arsenides typically appears in a low oxidation state approximating −3; this is discussed in textbooks as the −3 oxidation state. The label "arsenide" is also applied to binary compounds between arsenic and metals or metalloids where bonding ranges from largely ionic to covalent or metallic. For a general definition see the phrase arsenic in −3 state.

Physical and chemical properties

Properties vary widely. Some alkali or alkaline-earth arsenides show ionic behavior and are strongly basic, while transition-metal arsenides tend to be metallic, brittle or semiconducting. Many arsenides act as reducing agents because the arsenic can be oxidized to higher states. The distinction between ionic and metallic characters is important: simple salts emphasize anion/cation interactions (ionic) while intermetallic arsenides have delocalized electrons and a more metallic character.

Reactions and hazards

Arsenides react with acids to release arsine (AsH3), a toxic, flammable gas; this classical reaction is summarized in safety and preparative contexts (formation of arsine). Care is required when handling arsenides because of their potential to produce volatile arsenic hydrides and because many arsenide materials are toxic or environmentally persistent.

Uses, examples and significance

Representative compounds illustrate the range of chemistry: zinc arsenide (Zn3As2) is an example of a more ionic or mixed compound (zinc arsenide), while gallium arsenide (GaAs) is a covalent/semiconductor arsenide widely used in electronics and optoelectronics. Other metal arsenides occur as minerals or are investigated for magnetic, superconducting or thermoelectric behavior. For general background and reference material see basic descriptions and specialist sources (reducing behavior, metallic arsenides).

Distinctions and practical notes

  • Do not confuse arsenide (As3−) with arsenite (AsO3 3−) or arsenate (AsO4 3−); those are oxyanions with arsenic in higher oxidation states.
  • Arsenide materials span ionic salts, intermetallics and semiconductors—each class has different handling and environmental profiles.
  • Consult safety data before laboratory work because reactions with acids can generate arsine gas and other hazardous products; see technical literature at professional resources for procedures and risk mitigation.

For further reading, specialist chemistry texts and material-science reviews discuss bonding, electronic structure and applications of arsenide compounds in more detail; introductory entries and safety summaries are available from general reference sources (oxidation state context, ionic/metallic classification, compound examples).