What does arsenite mean?
Arsenite is a noun used in chemistry to denote a salt or ester of arsenious acid, in which arsenic exists in its trivalent, or +3, oxidation state. The term most commonly appears in scientific and environmental contexts, where arsenites are significant because many of them are markedly toxic. Compounds such as sodium arsenite were historically employed as pesticides, herbicides, and wood preservatives, and legacy contamination from these uses remains an environmental concern. In water chemistry, arsenite is distinguished from arsenate, its pentavalent (+5) counterpart, and the two forms behave differently: arsenite is typically more difficult to remove from water and is associated with greater acute toxicity. Because of this, arsenite is a key term in discussions of groundwater safety, industrial hygiene, and analytical chemistry, where precise identification of the arsenic species present is essential for assessing risk and choosing appropriate treatment methods.
nounA salt or ester of arsenious acid, containing arsenic in its trivalent (+3) state. Arsenites are typically highly toxic compounds.
- A salt or ester of arsenious acid, containing trivalent arsenic (As³⁺); such compounds are generally toxic and occur as environmental contaminants.
"The chemist tested the groundwater for traces of arsenite before declaring the well safe."
"Laboratory analysis revealed elevated levels of arsenite in the drinking water supply."
"In aqueous solution, the arsenite ion readily binds to soft metal cations, forming stable complexes."
The plural refers to multiple distinct arsenite compounds or species, e.g. sodium arsenite and potassium arsenite.
"Several arsenites were detected in the industrial waste samples."
Arsenites were once so widely used as pesticides and wood preservatives that old pressure-treated timber can still leach them into soil today.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of arsenite
Arsenite derives from arsenic, which entered English in the Middle Ages from Latin arsenicum, itself borrowed from Greek arsenikon, a term for the yellow pigment orpiment. The suffix -ite, standard in chemical nomenclature for salts of acids whose names end in -ous, was applied to denote salts of arsenious acid. Related terms sharing this root include arsenic, arsenical, and arsenious.
How arsenite is actually used
Arsenite is a technical term used chiefly in chemistry, toxicology, and environmental science. In environmental contexts it often refers specifically to the As(III) oxidation state, which is generally more toxic and more mobile in water than its pentavalent counterpart, arsenate.
Easily confused with arsenite
An arsenate contains arsenic in its pentavalent (+5) state, whereas an arsenite contains arsenic in its trivalent (+3) state.