The current IB Chemistry syllabus, first assessed in 2025, organizes chemistry around two connected concepts: Structure and Reactivity. SL and HL students study the same broad framework, but HL includes substantially more content, greater mathematical and conceptual depth, and longer examinations.
Both levels complete two examination papers and a scientific investigation worth 20% of the final grade. This reference breakdown explains the syllabus structure, teaching hours, assessment weightings, and the practical differences between SL and HL.
IB Chemistry SL vs HL comparison
| Feature | Chemistry SL | Chemistry HL |
|---|---|---|
| Recommended total teaching time | 150 hours | 240 hours |
| Syllabus content | 110 hours | 180 hours |
| Experimental programme | 40 hours | 60 hours |
| External assessment | 80% | 80% |
| Scientific investigation | 20% | 20% |
| Total examination time | 3 hours | 4 hours 30 minutes |
| Paper 1 | 1 hour 30 minutes, 55 marks | 2 hours, 75 marks |
| Paper 2 | 1 hour 30 minutes, 50 marks | 2 hours 30 minutes, 90 marks |
HL is not a separate chemistry course with an unrelated list of topics. It extends the SL foundation through additional syllabus statements and more demanding applications. For example, both levels study energetics, but entropy and spontaneity are HL content; elsewhere, HL students meet greater depth in bonding, equilibrium, acids and bases, redox chemistry, organic mechanisms, and analytical reasoning.
This distinction matters when selecting revision materials. An SL student does not need every HL extension, while an HL student cannot prepare effectively by mastering only the shared foundation.
How the IB Chemistry syllabus is organized
The syllabus replaces a collection of largely separate units with a conceptual roadmap. Its central relationship is that structure determines reactivity, while reactions transform structure.
| Organizing concept | Syllabus area | Recommended hours SL | Recommended hours HL |
|---|---|---|---|
| Structure | Structure 1: Models of the particulate nature of matter | 17 | 21 |
| Structure | Structure 2: Models of bonding and structure | 20 | 30 |
| Structure | Structure 3: Classification of matter | 16 | 31 |
| Reactivity | Reactivity 1: What drives chemical reactions? | 12 | 22 |
| Reactivity | Reactivity 2: How much, how fast and how far? | 21 | 31 |
| Reactivity | Reactivity 3: What are the mechanisms of chemical change? | 24 | 45 |
| Total syllabus content | 110 | 180 |
The hours are recommended teaching allocations, not examination weightings. The IB does not promise that a syllabus area receiving 20% of teaching time will provide exactly 20% of an examination's marks. Questions can also connect several areas, such as using bonding and energetics to explain a reaction or combining stoichiometry with equilibrium.
Students can review the complete sequence through the RevisionDojo IB Chemistry resource hub. More focused resources include Structure 2 bonding and structure notes and questions, equilibrium practice, and rate of reaction resources.
Assessment and weighting
| Component | SL format | HL format | Final weighting |
|---|---|---|---|
| Paper 1A | Multiple-choice questions | Multiple-choice questions | Part of Paper 1 |
| Paper 1B | Data-based and experimental-work questions | Data-based and experimental-work questions | Part of Paper 1 |
| Paper 1 overall | 55 marks, 1 hour 30 minutes | 75 marks, 2 hours | 36% |
| Paper 2 | Short-answer and extended-response questions, 50 marks | Short-answer and extended-response questions, 90 marks | 44% |
| Scientific investigation | Individual written report | Individual written report | 20% |
Paper 1 and Paper 2 assess knowledge, application, analysis, and evaluation. Calculators and the chemistry data booklet are permitted in both papers under the current format, so students must practise locating and applying information rather than trying to memorize every constant or equation. RevisionDojo's IB Chemistry data booklet resource can help students become familiar with this reference.
The scientific investigation is an open-ended task completed over approximately 10 hours. Students formulate a research question, gather and analyse data, and submit an individual report with a maximum overall word count of 3,000 words. It is internally assessed by the teacher and externally moderated by the IB.
What the experimental programme includes
The experimental programme receives 40 recommended hours at SL and 60 at HL. It includes practical work, the collaborative sciences project, and the scientific investigation.
| Experimental component | SL hours | HL hours |
|---|---|---|
| Practical work | 20 | 40 |
| Collaborative sciences project | 10 | 10 |
| Scientific investigation | 10 | 10 |
Practical work is not merely preparation for the investigation. Experimental design, uncertainty, graphical interpretation, data processing, and evaluation may be examined, particularly through Paper 1B.
How to revise the syllabus effectively
Organize revision by syllabus statement rather than by textbook chapter alone. For each statement, check that you can define the relevant terms, explain the chemistry, perform required calculations, interpret unfamiliar data, and answer using the appropriate command term.
A productive sequence is:
- Review one subtopic using concise notes.
- Recall definitions, equations, and explanations without looking.
- Complete topic-specific questions at the correct level.
- Record whether each error came from knowledge, reasoning, mathematics, or exam technique.
- Return to weak material before attempting mixed and timed papers.
The organic chemistry notes and questions illustrate how students can move from content review to targeted practice. RevisionDojo Flashcards can reinforce definitions and reaction patterns, while the Questionbank and Jojo AI can support focused practice and feedback. Nearer the examination, Mock Exams and Predicted Papers are more useful for developing timing and connecting different syllabus areas.
Common misunderstandings
Do not treat the recommended teaching hours as guaranteed topic weightings. Do not revise from pre-2025 resources without checking alignment, because the former option topics and three-paper examination structure no longer describe the current course.
It is also incorrect to assume that Paper 1 tests recall while Paper 2 tests understanding. Paper 1B includes data and experimental reasoning, and both papers assess application and analysis. Finally, the identical 20% investigation weighting does not make SL and HL equally demanding overall, because HL has 70 additional hours of syllabus content and substantially longer examinations.
Conclusion
The IB Chemistry syllabus gives SL and HL students a shared Structure and Reactivity framework, but HL adds considerably more depth, content, and examination time. At both levels, Paper 1 contributes 36%, Paper 2 contributes 44%, and the scientific investigation contributes 20%.
Successful preparation requires syllabus-level checking, experimental understanding, and regular application through questions. RevisionDojo's Chemistry Study Notes, Flashcards, Questionbank, and Jojo AI are most useful when combined in that order before progressing to timed Mock Exams.
Sources and referenced URLs
- Official IB Chemistry subject page
- Official IB Chemistry subject brief for first assessment 2025
- Official IB Chemistry curriculum updates
- Official IB Chemistry specimen papers
- RevisionDojo IB Chemistry resources
- RevisionDojo Structure 2 resources
- RevisionDojo equilibrium resources
- RevisionDojo rate of reaction resources
- RevisionDojo organic chemistry resources
- RevisionDojo IB Chemistry data booklet
