List of Common Polyatomic Ions:
Cations:
Symbol
NH4+
Name
Ammonium
Charge
+1
Symbol
Hg2+2
Name
Charge
Dimercury (I)
+2
Anions:
Symbol
C2H3O2C6H5COOHCO3HSO4HSO3BrO3ClO3ClO2CNH2PO4OHClOIO3NO3NO2ClO4IO4MnO4SCNFe(CN)63Fe(CN)64-
Name
Charge
Acetate
-1
Benzoate
-1
Bicarbonate
-1
Bisulfate
-1
Bisulfite
-1
Bromate
-1
Chlorate
-1
Chlorite
-1
Cyanide
-1
Dihydrogen Phosphate -1
Hydroxide
-1
Hypochlorite
-1
Iodate
-1
Nitrate
-1
Nitrite
-1
Perchlorate
-1
Periodate
-1
Permanganate
-1
Thiocyanate
-1
Hexacyanoferrate (III)
Hexacyanoferrate (II)
Variable Valence Cations:
Antimony (III) and (V)
Arsenic (III) and (V)
Cobalt (II) and (III)
Chromium (II), (III), and (VI)
Copper (I) and (II)
Gold (I) and (III)
Indium (I) and (III)
Iron (II) and (III)
Lead (II) and (IV)
Manganese (II), (III), (IV), and (VIII)
Mercury (II) Hg2+
Mercury (I) Hg22+
Platinum (II) and (IV)
Tin (II) and (IV)
✤Silver (1+)
✤Zinc (2+)
✤Cadmium (2+)
✤Forms only one type of ion and
Roman numerals are not used.
Symbol
CO32CrO42Cr2O72HPO42MoO42C2O42O22SiO32SO42SO32S2O32WO42AsO43AsO33BO33PO43PO33-
Name
Charge
Carbonate
-2
Chromate
-2
Dichromate
-2
Hydrogen Phosphate -2
Molybdate
-2
Oxalate
-2
Peroxide
-2
Silicate
-2
Sulfate
-2
Sulfite
-2
Thiosulfate
-2
Tungstate
-2
Arsenate
-3
Arsenite
-3
Borate
-3
Phosphate
-3
Phosphite
-3
Diatomic Molecules:
-3
-4
Bromine
Chlorine
Fluorine
Hydrogen
Iodine
Nitrogen
Oxygen
Br2
Cl2
F2
H2
I2
N2
O2
Prefixes (for non-metals):
1 – Mono
2 – Di
3 – Tri
4 – Tetra
5 – Penta
6 – Hexa
7 – Hepta
8 – Octa
9 – Nona
10 – Deca
Roman Numerals:
I One
IV Four
II Two
V Five
III Three VI Six
VII Seven
VIII Eight
IX Nine
X Ten