| carbide ion | C4- |
| carbon monoxide | CO |
| carbon dioxide | CO2 |
| carbonic acid | H2CO3 |
| bicarbonate ion | HCO3- |
| carbonate ion | CO32- |
| hydrogen cyanide | HCN |
| cyanide ion | CN- |
| cyanate ion, also isocyanate ion | CNO- |
| thiocyanate ion, also isothiocyanate ion | SCN- |
| carbon disulphide | CS2 |