Naming – ous vs ic

While naming ionic compounds using IUPAC involving multivalent metal ions the oxidation state or valency of the element is shown in brackets after the name of the metal using roman numerals. Example Iron (II) Sulfate = Fe2SO4, if you name the same compound using trivial naming system or the older naming system the compound is called Ferrous Sulfate.
Multivalent ions when named using the trivial system the metal with lower oxidation system always ends in -ous and the next higher oxidation number will end in -ic.
So Iron (III) Sulfate or Fe2(SO4)3 will be called Ferric Sulfate.
Cu+ = Cuprous ion
Cu2+ = Cupric ionĀ  and so on

 

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