Sulfites (also sulphites) are compounds that contain the sulfite ion SO (additive IUPAC name: trioxidosulfate(2−)). The sulfite ion's the conjugate base of sulfurous acid. Although the acid itself's elusive, its salts are widely used. Structure The structure of the sulfite anion can be described with three equivalent resonance structures. In each resonance structure, the sulfur atom's double-bonded to one oxygen atom with a formal charge of zero (neutral), and sulfur's singly bonded to the… (More on Sulfite)