polyatomic ions

ammonium - NH₄⁺

acetate - C₂H₃O₂⁻

bromate - BrO₃⁻

chlorate - ClO₃⁻

chlorite - ClO₂⁻

cyanide - CN⁻

bicarbonate (hydrogen carbonate) - HCO₃⁻

hydroxide - OH⁻

hypochlorite - ClO⁻

iodate - IO₃⁻

nitrate - NO₃⁻

nitrite - NO₂⁻

permanganate - MnO₄⁻

perchlorate - ClO₄⁻

thiocyanate - SCN⁻

carbonate - CO₃⁻²

chromate - CrO₄⁻²

dichromate - Cr₂O₇⁻²

oxalate - C₂O₄⁻²

peroxide - O₂⁻²

sulfate - SO₄⁻²

sulfite - SO₃⁻²

phosphate - PO₄⁻³

phosphite - PO₃⁻³

arsenate - AsO₄⁻³

borate - BO₃⁻³