Mole concept

relative atomic mass

• relative atomic mass of an element is the average mass of one atom of the element when compared with $\frac{1}{12}$ the mass of one atom of carbon-12

relative molecular mass (relative formula mass)

• relative molecular mass of a molecule is the average mass of one molecule of a substance when compared with $\frac{1}{12}$ the mass of one atom of carbon-12

avogadros law

• avagadros law states that equal volumes for all gases, under the same temperature and pressure contain the same number of particles