1.18 understand the term mole as the Avogadro number of particles (atoms, molecules, formulae, ions or electrons) in a substance

The Mole

The mole is a measure of an amount of substance.

One mole is the amount of a substance that contains 6 x 10²³ particles (atoms, molecules, formula, ions or electrons). 6 x 10²³ is the Avagadro Number.

e.g.

1 mol of Na contains 6 x 10²³ atoms of sodium

1 mol of H₂ contains 6 x 10²³ molecules of hydrogen

1 mol of NaCl contains 6 x 10²³ formulae of sodium chloride.