Common Polyatomic Ions

arsenate

AsO4 -3

bromate

BrO3 -

acetate

C2H3O2 -, or CH3COO -

oxalate

C2O4 -2

cyanide

CN -

carbonate

CO3 -2

hypochlorite

ClO -

chlorite

ClO2 -

chlorate

ClO3 -

perchlorate

ClO4 -

dichromate

Cr2O7 -2

chromate

CrO4 -2

hydrogen carbonate (also called bicarbonate)

HCO3 -

iodate

IO3 -

permanganate

MnO4 -

ammonium

NH4 +

nitrite

NO2 -

nitrate

NO3 -

peroxide

O2 -2

hydroxide

OH -

phosphite

PO3 -3

phosphate

PO4 -3

thiocyanate

SCN -

sulfite

SO3 -2

sulfate

SO4 -2