Polyatomic ions

There are groups of covalently bound atoms that act like a single ion.  An OH has a negative charge and will combine with one sodium ion like a chloride ion.  A list of these polyatomic ions is shown below.

Polyatomic ions and their names:


Formula Name
NH4+ Ammonium
OH- Hydroxide 
NO3- Nitrate
NO2- Nitrite
CH3CO2- Acetate
CN- Cyanide
MnO4- Permanganate
CO32- Carbonate
HCO3-‑ Bicarbonate
SO32- Sulfite
HSO3- Bisulfite
SO42- Sulfate
PO43- Phosphate
HPO42- Hydrogen phosphate
H2PO4- Dihydrogen phosphate
SiO32- Silicate
CrO42- Chromate