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Chemistry > Common Ions

Electrically charged atoms or groups of atoms are known as ions. Cations are positively charged ions and anions are negatively charged ions. the two combine in the proper proportions to form neutral (uncharged) ionic compounds.

The table below shows the common ions and charges.


Formula Name
Na+ sodium
K+ potassium
Fe2+ iron (II) or ferrous
Fe3+ iron (III) or ferric
Cu+ copper (I) or cuprous
Cu2+ copper (II) or cupric
NH4+ ammonium
H3O+ hydronium


Formula Name
OH- hydroxide
Cl- chloride
Br- bromide
I- iodide
CN- cyanide
S2- sulfide
NH2- amide
NO3- nitrate
NO2- nitrite
SO42- sulfate
SO32- sulfite
PO43- phosphate
HPO42- hydrogen phosphate
H2PO4- dihydrogen phosphate
ClO4- perchlorate
ClO3- chlorate
ClO2- chlorite
ClO- hypochlorite
MnO42- manganate
SiO44- silicate
O22- peroxide