Common Polyatomic Ions (Alphabetical order by ion name) NOTE: -ite ending means one less oxygen than the -ate form. Ion Ion Ion Ion Ion Name Ion Name Ion Name Ion Name Symbol Symbol Symbol Symbol - CH3CO2 2- - - Acetate or Dichromate Cr2O7 Hypobromite BrO Perrhenate ReO4 - CH3COO + Dihydrogen - - 3- Ammonium NH4 H2PO4 Hypochlorite ClO Phosphate PO4 Phosphate 3- Dihydrogen - - 3- Arsenate AsO4 H2PO3 Hypoiodite IO Phosphite PO3 Phosphite 3- 2- - 2- Arsenite AsO3 Dithionate S2O6 Iodate IO3 Plumbate PbO3 - 2- - 2- Azide N3 Dithionite S2O4 Iodite IO2 Plumbite PbO2 2- 3- - 2- Borate BO3 Ferricyanide Fe(CN)6 Isocyanate NCO Rhenate ReO4 - 4- 2- 2- Bromate BrO3 Ferrocyanide Fe(CN)6 Manganate MnO4 Selenate SeO4 - - - 2- Bromite BrO2 Fulminate CNO Nitrate NO3 Selenite SeO3 2- - - 2- Carbonate CO3 Hydrazide N2H3 Nitrite NO2 Silicate SiO3 - Hydrogen 2- 2- 2- Chlorate ClO3 HAsO4 Oxalate C2O4 Stannate SnO3 arsenate - Hydrogen - - 2- Chlorite ClO2 HCO3 Ozonide O3 Stannite SnO2 carbonate 2- Hydrogen 2- - 2- Chromate CrO4 HPO4 Perbromate BrO4 Sulfate SO4 Phosphate - Hydrogen 2- - 2- Chromite CrO2 HPO3 Perchlorate ClO4 Sulfite SO3 Phosphite 3- Hydrogen - - - Citrate C6H5O7 HSO4 Periodate IO4 Superoxide O2 Sulfate - Hydrogen - - - Cyanate OCN HSO3 Permanganate MnO4 Thiocyanate SCN Sulfite - - 2- 2- Cyanide CN Hydroxide OH Peroxide O2 Thiosulfate S2O3 2- Tungstate WO4 PREFIXES: per- = one more oxygen than -ate hypo- = one less oxygen than –ite Common Polyatomic Ions (Alphabetical order by formula) Ion Ion Ion Ion Ion Ion Name Ion Name Ion Name Symbol Name Symbol Symbol Symbol 3- 2- - 3- AsO3 Arsenite C2O4 Oxalate IO3 Iodate PO3 Phosphite 3- - - 3- AsO4 Arsenate CrO2 Chromite IO4 Periodate PO4 Phosphate 2- 2- 2- 2- BO3 Borate CrO4 Chromate MnO4 Manganate PbO2 Plumbite - 2- - 2- BrO Hypobromite Cr2O7 Dichromate MnO4 Permanganate PbO3 Plumbate - 3- - 2- BrO2 Bromite Fe(CN)6 Ferricyanide N3 Azide ReO4 Rhenate - 4- - - BrO3 Bromate Fe(CN)6 Ferrocyanide NCO Isocyanate SCN Thiocyanate - 2- Hydrogen - 2- BrO4 Perbromate HAsO4 NH2 Amide SO3 Sulfite arsenate - CH3CO2 - Hydrogen + 2- or Acetate HCO3 NH4 Ammonium SO4 Sulfate - carbonate CH3COO 3- 2- Hydrogen - 2- C6H5O7 Citrate HPO3 N2H3 Hydrazide S2O3 Thiosulfate Phosphite - 2- Hydrogen - 2- ClO Hypochlorite HPO4 NO2 Nitrite S2O4 Dithionite Phosphate - - Dihydrogen - 2- ClO2 Chlorite H2PO3 NO3 Nitrate S2O6 Dithionate Phosphite - 2- Dihydrogen - 2- ClO3 Chlorate H2PO4 O2 Superoxide SeO3 Selenite Phosphate - - Hydrogen 2- 2- ClO4 Perchlorate HSO3 O2 Peroxide SeO4 Selenate Sulfite - - Hydrogen - 2- CN Cyanide HSO4 O3 Ozonide SiO3 Silicate Sulfate - - - 2- CNO Fulminate IO Hypoiodite OCN Cyanate SnO2 Stannite 2- - - 2- CO3 Carbonate IO2 Iodite OH Hydroxide SnO3 Stannate 2- WO4 Tungstate NOTE: -ite ending means one less oxygen than the -ate form. PREFIXES: per- = one more oxygen than -ate hypo- = one less oxygen than -ite .