In chemistry, an arsenite is a chemical compound containing an arsenic oxoanion where arsenic has oxidation state +3. Note that in fields that commonly deal with groundwater chemistry, arsenite is used generically to identify soluble As^III anions. IUPAC have recommended that arsenite compounds are to be named as arsenate(III), for example ortho-arsenatite is called trioxidoarsenate(III). Ortho-arsenite contrasts to the corresponding anions of the lighter members of group 15, phosphite which has the structure HPO₃^2- and nitrite, NO₂^- which is bent.