Important Common Ions
H+
Li +
Na+
K+
Ag+
1+
hydrogen ion
lithium ion
sodium ion
potassium ion
silver ion
Mg 2+
Ca2+
Sr 2+
Ba2+
Zn2+
2+
magnesium ion
calcium ion
strontium ion
barium ion
zinc ion
3+
Al3+ aluminum ion
Sc3+ scandium ion
3N 3- nitride ion
P 3- phosphide ion
2O 2- oxide ion
S 2- sulfide ion
Se 2- selenide ion
1Ffluoride ion
Cl - chloride ion
Br - bromide ion
Iiodide ion
Most “-ide” anions are monatomic ions (one atom) like those above. Two exceptions are
hydroxide ion (OH -) and cyanide ion (CN -) shown with the polyatomic ions below.
Important Ions with Variable Charge
1+ or 2+
Cu+ copper (I) ion cuprous ion
Cu2+ copper (II) ion cupric ion
2+ or 3+
Fe2+ iron (II) ion
ferrous ion
3+
Fe
iron (III) ion ferric ion
2+ or 4+
Sn2+ tin (II) ion
stannous ion
4+
Sn
tin (IV) ion
stannic ion
Pb2+ lead (II) ion
plumbous ion
Each name specifies the charge of the ion in one of two ways:
Pb4+ lead (IV) ion plumbic ion
Modern System (preferred): Roman Numeral in parentheses indicates the charge of the cation. Ex. copper (I) ion means copper ion with a 1+ charge.
Old System: “-ous” suffix — lower charge; “-ic” suffix — higher charge. To understand these names you must know the two possible charges.
Ex. cuprous ion means copper ion with the “lower” charge (1+ vs 2+); cupric ion means copper ion with the “higher” charge (2+ vs 1+)
Important Polyatomic Ions
NH4+
Cation
1+
ammonium ion
Anions
123NO3- nitrate ion
CO32- carbonate ion
PO43- phosphate ion
NO2- nitrite ion
SO42- sulfate ion
ClO3 chlorate ion
SO32- sulfite ion
ClO2 chlorite ion
HPO42- hydrogen phosphate (not biphosphate ion)
OH
hydroxide ion
CN cyanide ion
All “-ate” and “-ite” ions contain oxygen. The “-ite” ion
Modern
Old
has one less oxygen than the “-ate” ion.
HCO3- hydrogen carbonate ion
bicarbonate ion
HSO4- hydrogen sulfate ion
bisulfate ion
The “bi-” prefix on the name of a 2- anion indicates a
HSO3- hydrogen sulfite ion
bisulfite ion
different ion. The “bi” ion has one hydrogen and a
H2PO4 dihydrogen phosphate (not biphosphate ion)
1- charge. Ex. sulfate SO42-; bisulfate HSO4- .