Alevel Chemistry Revision PC 01
Revision Material
Duration: 2nd – 8th March
Topic 1 Atoms, molecules and stoichiometry
This topic illustrates how quantitative relationships can be established when different substances react.
(The term relative formula mass or Mr will be used for all compounds including ionic compounds.)
Learning outcomes
Candidates should be able to:
1.1 Relative masses and (a) define and use the terms relative atomic, isotopic, molecular and formula masses,
12
atoms and molecules based on the C scale
1.2 The mole and the (a) define and use the term mole in terms of the Avogadro constant
Avogadro constant
1.3 The determination of (a) analyse mass spectra in terms of isotopic abundances (knowledge of the working of the
relative atomic mass spectrometer is not required)
masses, Ar (b) calculate the relative atomic mass of an element given the relative abundances of its
isotopes, or its mass spectrum
1.4 The calculation of (a) define and use the terms empirical and molecular formula
empirical formulae (b) calculate empirical and molecular formulae, using combustion data or composition by mass
1.5 Reacting masses and (a) write and construct balanced equations
volumes (of solutions (b) perform calculations, including use of the mole concept, involving:
and gases) 1. (i) reacting masses (from formulae and equations)
2. (ii) volumes of gases (e.g. in the burning of hydrocarbons)
(iii) volumes and concentrations of solutions
When performing calculations, candidates’ answers should reflect the number of significant figures given or asked for in the question.
When rounding up or down, candidates should ensure that significant figures are neither lost unnecessarily nor used beyond what is
justified (see also Practical Assessment, Paper 3, Display of calculation and reasoning on page 51).
(c) deduce stoichiometric relationships from calculations such as those in 1.5(b)
Revision Material
Duration: 2nd – 8th March
Topic 1 Atoms, molecules and stoichiometry
This topic illustrates how quantitative relationships can be established when different substances react.
(The term relative formula mass or Mr will be used for all compounds including ionic compounds.)
Learning outcomes
Candidates should be able to:
1.1 Relative masses and (a) define and use the terms relative atomic, isotopic, molecular and formula masses,
12
atoms and molecules based on the C scale
1.2 The mole and the (a) define and use the term mole in terms of the Avogadro constant
Avogadro constant
1.3 The determination of (a) analyse mass spectra in terms of isotopic abundances (knowledge of the working of the
relative atomic mass spectrometer is not required)
masses, Ar (b) calculate the relative atomic mass of an element given the relative abundances of its
isotopes, or its mass spectrum
1.4 The calculation of (a) define and use the terms empirical and molecular formula
empirical formulae (b) calculate empirical and molecular formulae, using combustion data or composition by mass
1.5 Reacting masses and (a) write and construct balanced equations
volumes (of solutions (b) perform calculations, including use of the mole concept, involving:
and gases) 1. (i) reacting masses (from formulae and equations)
2. (ii) volumes of gases (e.g. in the burning of hydrocarbons)
(iii) volumes and concentrations of solutions
When performing calculations, candidates’ answers should reflect the number of significant figures given or asked for in the question.
When rounding up or down, candidates should ensure that significant figures are neither lost unnecessarily nor used beyond what is
justified (see also Practical Assessment, Paper 3, Display of calculation and reasoning on page 51).
(c) deduce stoichiometric relationships from calculations such as those in 1.5(b)
