Common Polyatomic Ions Ion Name C2H3O2 or acetate CH3COO1ammonium NH4+ Ion S22SiF62- Name C2O42- oxalate hexafluorosilicate hydrogen carbonate (bicarbonate) hydrogen phosphate hydrogen phosphite hydrogen sulfate (bisulfate) hydrogen sulfite (bisulfite) hydronium hydroxide hypobromite hypochlorite hypoiodite hypophosphite iodate iodite BrO4- perbromate ClO4- perchlorate IO4MnO4- periodate permanganate arsenate HCO3- AsO33N3- arsenite azide HPO42HPO32- BO33- borate HSO4- BrO3BrO2C22CO32ClO3ClO2CrO42CrO2CNO- bromate bromite carbide carbonate chlorate chlorite chromate chromite cyanate HSO3H3O+ OHBrOClOIOPO23IO3IO2- cyanide MoO42- molybdate dichromate dihydrogen phosphate dihydrogen phosphite HPO4-2 monohydrogen phosphate Cr2O72H2PO4H2PO3- Name disulfide AsO43- CN- Ion NO3- nitrate NO2- nitrite O22PO43PO33P2O74SeO42SiO32SO42SO32C4H4O62B4O72CNS- or SCNS2O32- peroxide phosphate phosphite pyrophosphate selenate silicate sulfate sulfite tartrate tetraborate thiocyanate thiosulfate Common Polyatomic Ions Ion Name C2H3O2- or acetate CH3COO1ammonium NH4+ Ion S22SiF62- Name C2O42- oxalate hexafluorosilicate hydrogen carbonate (bicarbonate) hydrogen phosphate hydrogen phosphite hydrogen sulfate (bisulfate) hydrogen sulfite (bisulfite) hydronium hydroxide hypobromite hypochlorite hypoiodite hypophosphite iodate iodite BrO4- perbromate ClO4- perchlorate IO4MnO4- periodate permanganate arsenate HCO3- AsO33N3- arsenite azide HPO42HPO32- BO33- borate HSO4- BrO3BrO2C22CO32ClO3ClO2CrO42CrO2CNO- bromate bromite carbide carbonate chlorate chlorite chromate chromite cyanate HSO3H3O+ OHBrOClOIOPO23IO3IO2- cyanide MoO42- molybdate dichromate dihydrogen phosphate dihydrogen phosphite HPO4-2 monohydrogen phosphate Cr2O72H2PO4H2PO3- Name disulfide AsO43- CN- Ion NO3- nitrate NO2- nitrite O22PO43PO33P2O74SeO42SiO32SO42SO32C4H4O62B4O72CNS- or SCNS2O32- peroxide phosphate phosphite pyrophosphate selenate silicate sulfate sulfite tartrate tetraborate thiocyanate thiosulfate