The relative mass (
Mr) of atoms depends largely on the number of their protons and neutrons and, as shown at the right, relative masses are given with the symbol for the element in the periodic table. This module is concerned with calculations involving relative atomic masses and chemical formulae showing the number and types of atoms present in a substance.
On completion of the module you should be able
- to calculate, from relative atomic masses and the given formula for a substance, the relative mass of the formula unit
- to use relative masses of component atoms to identify the formula unit that has a given relative mass
- to identify compounds for which the empirical formula unit is different to the molecular formula
- to calculate the factor by which the empirical and molecular formulae are related when the relative molecular mass is known