The Most-Tested Topics in IB Chemistry HL
Every IB Chemistry HL past-paper question, mapped to the current syllabus and ranked by how often each topic is tested (2016–2025).
All topics (HL) ()
42 papers analysed · top 15 of 21 topics
| # | Topic | % of all HL questions | Questions | Avg marks |
|---|---|---|---|---|
| 1 | Introduction to organic chemistry | 24.2% | 226 | 3.2 |
| 2 | Collision theory and reaction rates | 12.6% | 118 | 3.8 |
| 3 | Covalent bonding | 12.3% | 115 | 3.8 |
| 4 | Proton transfer reactions (acids and bases) | 12.2% | 114 | 2.9 |
| 5 | Electron transfer reactions (redox and electrochemistry) | 12.1% | 113 | 2.8 |
| 6 | The mole concept | 11.6% | 108 | 4.6 |
| 7 | Periodic trends in atomic properties | 11.1% | 104 | 2.3 |
| 8 | Reacting masses and volumes | 10.3% | 96 | 5.3 |
| 9 | Enthalpy of reaction | 8.4% | 78 | 3.3 |
| 10 | Atomic number, mass number and isotopes | 7.4% | 69 | 3.9 |
| 11 | Reactivity 2: Energetics and Kinetics | 7.1% | 66 | 6 |
| 12 | Structure 2: Electron Configuration | 6.9% | 64 | 3.5 |
| 13 | Dynamic equilibrium | 6.8% | 63 | 2.8 |
| 14 | Organic reaction mechanisms | 6.2% | 58 | 3.3 |
| 15 | Metallic bonding | 4.7% | 44 | 2.7 |
How this was measured
Based on OwlsPrep's database of IB Chemistry HL past papers (2016–2025), 933 questions each tagged to its syllabus topic and mapped to the current IB syllabus via our topic crosswalk. “% of all HL questions” = the share of all tagged IB Chemistry HL questions that test the topic. Topics no longer in the current syllabus are excluded; because one question can test several topics, shares do not sum to 100%. Figures are aggregate statistics from question metadata — no exam questions or mark schemes are reproduced.
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