1. The mass of atoms

2. Objectives Today we will learn: What atomic number and mass number mean The relative masses of subatomic particles What isotopes are That masses of atoms can be compared by their relative atomic masses That carbon 12 is used as a standard to measure relative atomic mass from That the relative masses of compounds can be calculated

3. True or False Atoms are charged particles Atoms contain charged particles Electrons are found in energy levels or shells Electrons have a negative charge Protons are found in the nucleus of an atom Neutrons are found in shells around the outside of an atom

4. What do you know about the atom…

5. Find the number of Protons, Electrons and Neutrons and the mass number of the following… Li Na Al C Ar Ca Au N W Bi Hg 4+ F - Tc 3+

6. What about chlorine?

7. Isotope Same number of protons different number of neutrons

8. Find the link between these 12g of C 197g of Au 7g of Li 88g of Sr 56g of Fe 119g of Sn 48g of Ti 23g of Na 24g of Mg 91g of Zr 40g of Ca 84g of Kr 11g of B 127g of I 80g of Br 1g of H 75g of As

9. The Mole Is based on Avogardos number 6.022 x 10 23 particles in one mole

10. Find the relative mass of the following… Li Na CO 2 Al 2 O 3 CH 4 Ar CaCO 3 Au N 2 W Bi H 2 O CuSO 4 5H 2 O

11. Working out the number of moles 12g carbon 16g oxygen gas 9g gold 45g hydrogen 10g argon Mass N o MolesRelative Mass

12. Objectives Today we will learn: What atomic number and mass number mean The relative masses of subatomic particles What isotopes are That masses of atoms can be compared by their relative atomic masses That carbon 12 is used as a standard to measure relative atomic mass from That the relative masses of compounds can be calculated You can now Define atomic number and mass number Use the periodic table to get atomic & mass number to work out the number of each subatomic particle that an atom has Give a definition of atomic mass Calculate relative formula masses State what a mole is

13. Calculations with Percentages, Formulae & Equations You will learn… How to calculate the percentage of an element in a compound from its formula How to calculate the empirical formulae of a compound from its percentage composition That balanced symbol equations show the relative numbers of molecules of reactants and products in a reaction That balanced symbols equations can be used to calculate the masses of reactants and products Teaser… How could you work out the % of carbon in CaCO 3

14. Define Click herehere

15. Percentage of an element in a compound By Mass! Find the relative mass of the compound Divide the total relative mass of the element of interest by the relative mass of the compound. Mass of element of interest Total Relative mass of substance

16. Percentage of an element in a compound For example… Find the percentage of oxygen in magnesium oxide Magnesium oxide = MgO Mg = 24 O = 16 MgO = 40 16/40 = 40% Mass of element of interest Total Relative mass of substance

17. Questions

18. Empirical Formulae Empirical formula Haiku Convert mass to mole Then divide it by the small Multiply til whole

19. Example NaSO Percentage29.1%40.5%30.4% Convert Mass to Mole 29.1 / 23 = 1.265217 40.5 / 32 1.265625 30.4 / 16 1.9 Then divide it by the small 1.265217 = 1 1.265625 1.265217 = 1 1.9 1.265217 = 1.5 Multiply til whole X 2 223 Convert mass to mole Then divide it by the small Multiply til whole

20. Questions

21. Calculations with Percentages, Formulae & Equations You will learn… How to calculate the percentage of an element in a compound from its formula How to calculate the empirical formulae of a compound from its percentage composition That balanced symbol equations show the relative numbers of molecules of reactants and products in a reaction That balanced symbols equations can be used to calculate the masses of reactants and products You have learnt… To calculate the percentage composition of an element in a compound To calculate the empirical formulae of compounds from percentage composition.