OLD SCHOOL NAMING (based on Latin, and the common forms of the ions) Symbol Systematic Name Common Name Cu+ copper(I) ion cuprous ion Cu2+ copper(II) ion cupric ion Fe2+ iron(II) ion ferrous ion Fe3+ iron(III) ion ferric ion Sn2+ tin(II) ion stannous ion Sn4+ tin(IV) ion stannic ion Cr2+ chromium(II) ion chromous ion Cr3+ chromium(III) ion chromic ion Mn2+ manganese(II) ion manganous ion Mn3+ manganese(III) ion manganic ion Symbol Systematic Name Common Name Hg22+ mercury(I) ion mercurous ion Hg2+ mercury(II) ion mercuric ion Pb2+ lead(II) ion plumbous ion Pb4+ lead(IV) ion plumbic ion Co2+ cobalt(II) ion cobaltous ion Co3+ cobalt(III) ion cobaltic ion Ni2+ nickel(II) ion nickelous ion Ni4+ nickel(IV) ion nickelic ion Ti3+ titanium(III) ion titanous ion Ti4+ titanium(IV) ion titanic ion