Naming Compounds with Transition Metals + Sn & Pb

What is the Roman Numeral?Naming Compounds with Transition Metals + Sn & PbHow do I figure out charge on cation?When naming ionic compounds with a transition metal or Sn & Pb, you must include a roman numeral in the name to indicate the positive charge on the cation.Examples:CuCl2 = Copper (II) chlorideCo(NO3)3 = Cobalt (III) nitrateHow do I figure out charge on cation?From the finished formula, you must work backwards to determine the positive charge. You also must know the negative charge on anion.Example: AuCl3

Practice Problems:Cr2O3

Sn(C2H3O2)2

Cu3PO4