1. Roman Numbers used in Chemical Formulae

2. For example, Copper has two valencies, 1 and 2
Many Transition Metal Elements (the block in the middle of the Periodic Table) can have more than one valency
For example, Copper has two valencies, 1 and 2
The valency of such an element in a compound is written in brackets immediately after the name of the element.
Do you know your roman numerals?

3. Examples… 1. Copper(I) oxide 1 2 Cu O Formula is Cu2O
2. Tin(IV) carbonate 2 1 4 2 Sn
CO3
Formula is Sn(CO3)2

4. TRY… 1. Silver(I) sulphate Answer Ag2SO4 2. Lead(IV) oxide Answer PbO2
Answer Fe2S3
3. Iron(III) sulphide
4. Tin(II) phosphate
Answer Sn3(PO4)2
Answer NiCl2
5. Nickel(II) chloride