Ion Symbol & Name Rules
When an ion symbol is written you must include the charge of the ion.
When an ion name is written you do not include the charge of the ion.
- Ions are charged particles that have a symbol or formula and a name.
Cation (+) Ion Rules
Elemental cation names look like the element names, so they must end in
the word ion.
Elemental cation charges are determined by their family on the Periodic
Ions that can hold more than one charge must have different names for
There are two naming methods.
Classical Names: Suffix -ic means greater positive charge
Suffix -ous means lesser positive charge
Stock Names: Roman Numerals indicate the positive charge
Odd Ions That Do Not Follow Cation Rules As Stated: NH41+
Anion (-) Ion Rules
- Elemental anion names end in the suffix -ide.
- Anion suffixes -ate & -ite mean that oxygen is present.
Suffix -ate means the number of oxygens can be predicted by the Periodic
Suffix -ite means one less oxygen than -ate. Yet both hold the same
- Oxygen always acts as the Oxide ion with a (-2) charge, so almost
anything that attaches to oxide to form an ion must be positive in charge.
(Two negative things repel.)
- Prefix bi- means that a Hydrogen Ion H1+ has attached to an
anion and decreased its charge by one
Odd Ions That Do Not Follow Anion Rules As Stated:
CN 1- cyanide OH 1- hydroxide C2H3O2 1- acetate MnO4 1- permanganate
ClO 1- hypochlorite hypo- prefix means under, so one
oxygen under chlorite
ClO21- chlorite ClO31- chlorate
ClO41- perchlorate per- (hyper-) prefix
means above, so one oxygen above chlorate
H2PO41- hydrogen biphosphate or
dihydrogen phosphate Di- prefix means two
Cr2O7 2- dichromate C2O4 2- oxalate