1. 1.Each element has a different symbol 2.The formula for a compound shows the elements in the compound 3.It also shows the ratio of the atoms of different elements in the compound Chemical Formula

2. The Periodic Table

3. Chemical Formula

4. Atomic Structure

5. Electron shells

7. 1.Word equations use the names of the reactants and products to describe a reaction Word equations

9. 1.Chemical equations use the chemical formulae of the reactants and products to describe a reaction 2.The total mass of the product(s) of a chemical reaction must equal the total mass of the reactant(s) 3.Therefore chemical equations must be balanced 4.The total number of atoms of one element should be the same on both sides of the equation Chemical equations

10. Balancing equations

11. 1.Atoms of different elements have different masses 2.The relative atomic mass (A r ) is the mass of the elements compared to the mass of a hydrogen atom Relative atomic masses

12. Relative atomic mass Relative atomic masses

13. 1.The relative formula mass (M r ) is the relative mass of a molecule compared to the mass of a hydrogen atom Relative Formula Mass Relative formula mass

15. 1.The unknown mass of a reactant or product can be worked out by using the known masses of the other reactants and products Equation calculations

16. Calculations from Equations Calculations from equations

17. Calculations from Equations Calculations from equations