When Metals Have More Than One Cation

Some transition metals can have more than one cation Some transition metals can have more than one cation. For example, copper can have a +1 or a +2 charge. We can tell the charge of the metal because it is written in as a roman numeral in the name. This is called the stock system for naming.

E.g. write the formula for copper (I) sulfide Cu 1+ S2- Cu2S

E.g. write the formula for copper (II) sulfide Cu 2+ S2- CuS

Naming and the Stock System We can find the name of a compound using the stock system. We use a reverse criss-cross method

Naming and the Stock System FeCl3 Iron can have a +2 or a +3 charge. Fe? Cl1- There are 3 negative charges, therefore Fe must be +3. We would call it Iron (III) chloride.

Naming and the Stock System Cu2S Copper can have a +1 or a +2 charge. 2 Cu? S2- Two atoms of Copper (I) will make a 2+ charge (1+ x 2 atoms of Cu= 2+). We would call it Copper (I) sulfide.