Polyatomic Ions Chart
Use this table to find the formula and charge of common polyatomic ions used in ionic compounds.
| Ion | Formula | Charge | Examples |
|---|---|---|---|
| ammonium | NH4 | +1 | NH4Cl, (NH4)2SO4 |
| hydroxide | OH | -1 | NaOH, Ca(OH)2 |
| nitrate | NO3 | -1 | NaNO3, Ca(NO3)2 |
| nitrite | NO2 | -1 | NaNO2 |
| sulfate | SO4 | -2 | Na2SO4, Fe2(SO4)3 |
| sulfite | SO3 | -2 | Na2SO3 |
| carbonate | CO3 | -2 | CaCO3, Na2CO3 |
| bicarbonate | HCO3 | -1 | NaHCO3 |
| phosphate | PO4 | -3 | Na3PO4, Ca3(PO4)2 |
| acetate | C2H3O2 | -1 | NaC2H3O2 |
| chlorate | ClO3 | -1 | KClO3 |
| perchlorate | ClO4 | -1 | NaClO4 |
| cyanide | CN | -1 | NaCN |
| permanganate | MnO4 | -1 | KMnO4 |
| chromate | CrO4 | -2 | K2CrO4 |
| dichromate | Cr2O7 | -2 | K2Cr2O7 |