Common Polyatomic Ions

C₂H₃O₂^-

Acetate

C₆H₅COO^-

Benzoate (charge = -1)

HCO₃^-

Bicarrbonate

HSO₄^-

Bisulfate

HSO₃^-

Bisulfite

BrO₃^-

Bromate (charge = -1)

ClO₃^-

Chlorate

ClO₂^-

Chlorite

CN^-

Cyanide

H₂PO₄^-

Dihydrogen phosphate

OH^-

Hydroxide

ClO^-

Hypochlorite

IO₃^-

Iodate (charge = -1)

NO₃^-

Nitrate

NO₂^-

Nitrite

ClO₄^-

Perchlorate

IO₄^-

Periodate (charge = -1)

MnO₄^-

Permanganate

SCN^-

Thiocyanate (charge = -1)

Fe(CN)₆^3-

Hexacyanoferrate (III) - (charge = -3)

Fe(CN)₆^4-

Hexacyanoferrate (II) - (charge = -4)

CO₃^2-

Carbonate

CrO₄^2-

Chromate

Cr₃O₇^2-

Dichromate

HPO₄^2-

Hydrogen Phosphate

MoO₄^2-

Molybdate (charge = -2)

C₂O₄^2-

Oxalate (charge = -2)

O₂^2-

Peroxide

SiO₃^2-

Silicate (charge = -2)

SO₄^2-

Sulfate

SO₃^2-

Sulfite

S₂O₃^2-

Thiosulfate (charge = -2)

WO₄^2-

Tingstate (charge = -2)

AsO₄^3-

Arsenate (charge = -3)

AsO₃^3-

Arsenite (charge = -3)

BO₃^3-

Borate (charge = -3)

PO₄^3-

Phosphate

PO₃^3-

Phosphite (charge = -3)

NH₄⁺

Ammonium

Hg₂⁺²

Dimercury (I) - (charge = +2)