# 4.3.2.1

4.3.2.1 Moles (HT only)

## Content

• Chemical amounts are measured in moles. The symbol for the unit mole is mol.

The mass of one mole of a substance in grams is numerically equal to its relative formula mass.

• One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.

The number of atoms, molecules or ions in a mole of a given substance is the Avogadro constant. The value of the Avogadro constant is 6.02 x 1023 per mole.

Students should understand that the measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO2).

Students should be able to use the relative formula mass of a substance to calculate the number of moles in a given mass of that substance and vice versa.

WS 4.1Use scientific vocabulary, terminology and definitions.

WS 4.2 Recognise the importance of scientific quantities and understand how they are determined.

WS 4.3 Use SI units (eg kg, g, mg; km, m, mm; kJ, J) and IUPAC chemical nomenclature unless inappropriate.

WS 4.5Interconvert units.

WS 4.6 Use an appropriate number of significant figures in calculation.

MS 1a - Recognise and use expressions in decimal form

MS 1b - Recognise and use expressions in standard form

MS 1c Use ratios, fractions and percentages

MS 2a Use an appropriate number of significant figures

MS 3a Understand and use the symbols: =, <, <<, >>, >, ∝ , ~

MS 3b Change the subject of an equation