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Which A-Level H2 Chemistry topics come up most often?
We counted every question in 29 A-Level H2 Chemistry papers in Rae's library: 1127 questions across 31 topics. The most common single topic is Transition metals: properties and complex ion colour, at 7.2% of all questions.
Every topic, ranked
| Topic | Questions | Share | Papers | Avg marks |
|---|---|---|---|---|
| Transition metals: properties and complex ion colour | 81 | 7.2% | 21 | 1.9 |
| Chemical bonding types and molecular shapes | 73 | 6.5% | 23 | 1.5 |
| Nitrogen-containing organic compounds | 66 | 5.9% | 18 | 1.7 |
| Periodic trends across period 3 and groups 2/17 | 62 | 5.5% | 22 | 2.2 |
| Isomerism: structural, cis-trans, and optical | 54 | 4.8% | 21 | 1.4 |
| Hydrocarbons: alkanes, alkenes, arenes reactions | 51 | 4.5% | 19 | 1.6 |
| Chemical equilibrium and equilibrium constants | 50 | 4.4% | 20 | 1.6 |
| Thermochemistry: enthalpy changes and Hess's Law | 45 | 4.0% | 16 | 1.5 |
| Reaction rates, order and rate equations | 43 | 3.8% | 16 | 1.8 |
| Aqueous acid-base equilibria and pH calculations | 42 | 3.7% | 19 | 1.8 |
| Mole concept and stoichiometric calculations | 41 | 3.6% | 24 | 1.4 |
| Batteries, fuel cells, and electrolysis applications | 41 | 3.6% | 17 | 1.9 |
| Carboxylic acids and derivatives chemistry | 41 | 3.6% | 16 | 2.1 |
| Solubility product and common ion effect | 40 | 3.5% | 15 | 1.5 |
| Ideal gas behaviour and gas laws | 37 | 3.3% | 17 | 1.6 |
| Electrochemistry: electrode potentials and cells | 37 | 3.3% | 16 | 1.6 |
| Halogen derivatives and nucleophilic substitution | 37 | 3.3% | 15 | 1.8 |
| Carbonyl compounds: aldehydes and ketones | 33 | 2.9% | 12 | 1.9 |
| Atomic structure and electron arrangement | 32 | 2.8% | 20 | 1.1 |
| Organic reaction mechanisms overview | 28 | 2.5% | 13 | 2.4 |
| Activation energy and catalysis mechanisms | 27 | 2.4% | 14 | 1.6 |
| Ionisation energies and orbital shapes | 24 | 2.1% | 14 | 2.1 |
| Entropy and Gibbs free energy | 23 | 2.0% | 11 | 1.7 |
| Acid-base theories (Arrhenius, Brønsted-Lowry, Lewis) | 21 | 1.9% | 11 | 1.4 |
| Buffer solutions and their applications | 20 | 1.8% | 12 | 1.9 |
| Intermolecular forces and hydrogen bonding | 20 | 1.8% | 12 | 1.8 |
| Bonding effects on physical properties | 19 | 1.7% | 9 | 1.8 |
| Alcohols and phenols reactivity | 16 | 1.4% | 12 | 1.6 |
| Organic nomenclature and structural representations | 14 | 1.2% | 8 | 2.6 |
| Haber process and industrial equilibrium application | 5 | 0.4% | 2 | 1.6 |
| Acid-base theories (Arrhenius, Bronsted-Lowry, Lewis) | 4 | 0.4% | 3 | 1.5 |
How to use this
Topic frequency is a guide to where revision time pays back, not a prediction. The three topics that appear most here (Transition metals: properties and complex ion colour, Chemical bonding types and molecular shapes, Nitrogen-containing organic compounds) are worth being fluent in, but a topic near the bottom of the table can still carry a whole question in any given year.
Method, and what this is not
These counts come from real A-Level H2 Chemistry papers held in Rae's library (papers dated 2009 to 2025), which include school preliminary papers as well as national papers. Each question is labelled with one topic. This is a count of what our library contains, not an official SEAB distribution, and it does not tell you what will be set in a future exam. Questions that could not be labelled with a single topic are excluded from the counts.
You are welcome to cite or link to this page. If you would like the underlying counts in another format, get in touch through the A-Level H2 Chemistry page.