nitrite

The term nitrite (NO₂^-) is used for the compound nitrogen dioxide (NO₂) when singly ionized (specifically, as an anion, with one extra electron). (NO₂ is the compound with molecules each consisting of one nitrogen and two oxygen atoms.) The term nitrite is also used to indicate a compound that includes the anion, presumably with an ionic bond, resulting in a nitrite salt. Example such salts are those consisting the anion bound to a sodium or potassium atom i.e., sodium nitrite and potassium nitrite. The presence of nitrite ions is indicated by the spectra of some astronomical objects and some nitrite compounds may be biosignatures.