There are a number of ions that are not individual atoms but are composed of multiple atoms that are covalently bonded together. However, this group of atoms is most stable when it has either lost of gained an electron and thus existed as a charged ion. These polyatomic ions are extremely common in chemistry and thus it is important to be able to both recognize and name them. While there are many such ions in the world, you are responsible for knowing the ions listed in the following tables.
| Name | Formula |
|---|---|
| ammonium | NH4+ |
| nitrite | NO2− |
| nitrate | NO3− |
| sulfite | SO32− |
| sulfate | SO42− |
| hydrogen sulfate (aka: bisulfate) |
HSO4− |
| thiosulfate | S2O32− |
| oxalate | C2O42− |
| hydroxide | OH− |
| Name | Formula |
|---|---|
| phosphite | PO33− |
| phosphate | PO43− |
| hydrogen phosphate | HPO42− |
| dihydrogen phosphate | H2PO4− |
| perchlorate | ClO4− |
| chlorate | ClO3− |
| chlorite | ClO2− |
| hypochlorite | ClO− |
| bromate | BrO3− |
| iodate | IO3− |
| Name | Formula |
|---|---|
| acetate acetate |
CH3COO− C2H3O2− |
| carbonate | CO32− |
| hydrogen carbonate (aka: bicarbonate) |
HCO3− |
| chromate | CrO42− |
| dichromate | Cr2O72− |
| permanganate | MnO4− |
| peroxide | O22− |
| cyanide | CN− |
| cyanate | OCN− |
| thiocyanate | SCN− |
| IUPAC Name | older name | Formula |
|---|---|---|
| copper(I) | cuprous | Cu+ |
| copper(II) | cupric | Cu2+ |
| iron(II) | ferrous | Fe2+ |
| iron(III) | ferric | Fe3+ |
| lead(II) | plumbous | Pb2+ |
| lead(IV) | plumbic | Pb4+ |
| mercury(I) | mercurous | Hg22+ |
| mercury(II) | mercuric | Hg2+ |
| tin(II) | stannous | Sn2+ |
| tin(IV) | stannic | Sn4+ |