Methodology

This list is based on analysis of Pearson Edexcel International A-Level Chemistry past papers (2019–2024), examiner reports, mark schemes and specification. Topics are ranked by frequency and mark allocation.

Top 10 most frequently tested topics

1. Organic chemistry

Evidence: Alkanes, alkenes, alcohols, carbonyls, aromatic chemistry. Examiner reports note naming, mechanisms and bonding errors.

Covers: homologous series; mechanisms; alcohols; aldehydes/ketones; carboxylic acids; benzene; polymers.

2. Mole calculations and stoichiometry

Evidence: Appears in almost every paper. Examiner reports note limiting reagent and units.

Covers: mole concept; reacting masses; empirical/molecular formula; titration calculations; gas volumes.

3. Energetics and thermochemistry

Evidence: Enthalpy, Hess’s law, bond enthalpy. Examiner reports note sign errors and incomplete definitions.

Covers: enthalpy change; Hess’s law; bond enthalpy; Born-Haber cycles; entropy.

4. Chemical bonding

Evidence: Ionic, covalent, metallic; shapes; intermolecular forces. Examiner reports note hybridisation errors.

Covers: bonding types; VSEPR; shapes; polarity; intermolecular forces.

5. Equilibria (Kc, Kp)

Evidence: Le Chatelier; equilibrium constants. Examiner reports note equilibrium expression and units.

Covers: dynamic equilibrium; Le Chatelier; Kc; Kp; effect of conditions.

6. Acids, bases and pH

Evidence: Titration, buffers, pH calculations. Examiner reports note weak acid and buffer errors.

Covers: Brønsted-Lowry; pH; titration curves; buffers; indicators.

7. Electrochemistry

Evidence: Electrolysis; electrode potentials. Examiner reports note half-equation errors.

Covers: electrolysis; E°; electrochemical cells; fuel cells.

8. Kinetics

Evidence: Rate equations; order; Arrhenius. Examiner reports note order of reaction.

Covers: rate equations; order; half-life; catalysts; Arrhenius equation.

9. Periodicity and Group chemistry

Evidence: Periodic trends; Group 2, 17. Examiner reports note trend explanations.

Covers: ionisation energy; electronegativity; Group 2; Group 17; transition elements.

10. Atomic structure and spectroscopy

Evidence: Electronic configuration; mass spectrometry; IR, NMR. Examiner reports note splitting and chemical shift.

Covers: electronic configuration; mass spec; IR; NMR; identification.

Revision priority

Organic chemistry and mole calculations carry the most marks. Show working and check units. See common mistakes.

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Sources: Edexcel past papers 2019–2024, examiner reports, specification.