1. You’re going to need to get your pens ready for this one! Calculations in chemistry And quickly finishing off metallic structures

2. Relative atomic mass - A r Just another way of saying how heavy different atoms are compared with the mass of one atom of carbon – 12 (regular carbon!) Mass number Q. What does the atomic mass number represent? A. Total number of protons and neutrons found in an atoms nucleus Atomic number Number of protons present

3. Relative atomic mass - A r ElementArAr H1 C12 O16 Mg24 Cl35. Table.1. Different elements and their different A r Relative atomic mass is easy!! It’s the same value as the mass number – it just sounds scarier! So what does this tell us about Mg and H?

4. Relative formula mass - M r To find the relative formula mass (M r ) of a compound, you just add together the A r values for all the atoms in its formula. Example 1: Find the M r of carbon monoxide (CO). The A r of carbon is 12 and the A r of oxygen is 16. So the M r of carbon monoxide is 12 + 16 = 28. Example 1: Find the M r of carbon monoxide (CO). The A r of carbon is 12 and the A r of oxygen is 16. So the M r of carbon monoxide is 12 + 16 = 28. O 16 8

5. Relative formula mass - M r Example 2:Find the M r of sodium oxide-Na 2 O The A r of sodium is 23 and the A r of oxygen is 16. So the M r of sodium oxide is (23 x 2) + 16 = 62.

6. Carbon dioxide Sulphur dioxide SO 2 Calcium carbonate CaCO 3 Sodium hydroxide NaOH Sulphuric acid H 2 SO 4 Hydrochloric acid HCl Copper sulphate CuSO 4 Magnesium chloride MgCl 2 Sodium carbonate Na 2 CO 3 Find the M r of these: