Polyatomic ions

Ammonium ion

NH₄⁺

Hydronium ion

H₃O⁺

Hydroxide ion

OH⁻

Cyanide ion

CN⁻

Nitrite ion

NO₂⁻

Nitrate ion

NO₃⁻

Hypochlorite ion

ClO⁻ or OCl⁻

Chlorite ion

ClO₂⁻

Chlorate ion

ClO₃⁻

Perchlorate ion

ClO₄⁻

Permanganate ion

MnO₄⁻

Acetate ion

C₂H₃O₂⁻

Oxalate ion

C₂O₄²⁻

Carbonate ion

CO₃²⁻

Hydrogen carbonate ion (bicarbonate ion)

HCO₃⁻

Sulfite ion

SO₃²⁻

Hydrogen sulfite ion (bisulfite ion)

HSO₃⁻

Sulfate ion

SO₄²⁻

Hydrogen sulfate ion (bisulfate ion)

HSO₄⁻

Thiocyanate ion

SCN⁻

Thiosulfate ion

S₂O₃²⁻

Chromate ion

CrO₄²⁻

Dichromate ion

Cr₂O₇²⁻

Phosphate ion

PO₄³⁻