Cоmmоn Pоlyаtomic Cаtions Cаtion Name NH4+ Ammonium ion H3O+ Hydronium ion Common Polyatomic Anions Anion Name C2H3O2- Acetate ion CO32- Carbonate ion ClO3- Chlorate ion ClO2- Chlorite ion CrO42- Chromate ion CN- Cyanide ion Cr2O72- Dichromate ion HCO3- Hydrogen carbonate ion HSO4- Hydrogen sulfate ion OH- Hydroxide ion ClO- Hypochlorite ion NO3- Nitrate ion NO2- Nitrite ion ClO4- Perchlorate ion MnO4- Permanganate ion PO43- Phosphate ion SO42- Sulfate ion SO32- Sulfite ion