Hi Diploma students
These are comprehensive revision notes for IB Diploma Programme Chemistry, free and open to anyone. They cover the syllabus first taught in 2023 and first examined in 2025 — all twenty-two sub-topics of Structure and Reactivity, standard level and higher level, plus the internal assessment and the core.
The 2023 course is not the old one with the topics renumbered. Options are gone, the syllabus is organised around two concepts instead of eleven topics, and the papers changed shape. A great deal of material still circulating online describes a course that no longer exists, so if you have inherited notes from an older sibling, read Start here before you trust them.
Please take note that although succinct notes are essential towards your revision, they should not be the only materials you cover — working through problems from your textbook and past papers is just as important, and in chemistry so is time in the laboratory.
Happy revising. — Mr. Suta
🧭Start here
What changed in 2023, how Structure and Reactivity fit together, what separates SL from HL, how Papers 1A, 1B and 2 are built, and what is in the data booklet so you never memorise it. Ten minutes here will save you a term of guessing.
📚The syllabus
Two organising concepts, six topics, twenty-two sub-topics. Structure is what matter is; Reactivity is what it does. The syllabus states the relationship in one sentence, and it is worth taking literally: structure determines reactivity, which in turn transforms structure. Material marked AHL on a page is additional higher level — HL candidates only.
Structure 1 — Models of the particulate nature of matter
Where chemistry starts counting. Elements, compounds and mixtures; inside the atom; how electrons are arranged and what light tells us about that; the mole, which is the single most important idea in the course; and the ideal gas as a model with known limits. SL 17 hours, HL 21.
Structure 2 — Models of bonding and structure
Three bonding models — ionic, covalent, metallic — each pushed until it breaks, and then the honest admission that bonding is a continuum rather than three boxes. S2.2 is the longest sub-topic in the course and carries most of the AHL load. SL 20 hours, HL 30.
Structure 3 — Classification of matter
Two great classification systems: the periodic table for elements and functional groups for organic compounds. Both exist for the same reason — so that you can predict the properties of something you have never met. At HL this is the biggest single jump in the course, from 16 hours to 31, because transition elements and analytical spectroscopy are both here.
Reactivity 1 — What drives chemical reactions?
Energy. Measuring enthalpy changes in a polystyrene cup, then getting the ones you cannot measure out of energy cycles, then fuels, and finally — at HL only — the second reason reactions happen at all, which is entropy. SL 12 hours, HL 22.
Reactivity 2 — How much, how fast and how far?
Three separate questions that students constantly merge into one. How much is stoichiometry, how fast is kinetics, how far is equilibrium — and a reaction can be fast and go nowhere, or complete and take a century. Keeping the three apart is most of the skill. SL 21 hours, HL 31.
Reactivity 3 — What are the mechanisms of chemical change?
The syllabus classifies reactions by what happens to the electrons: a proton moves (acids and bases), an electron moves (redox), a single electron is shared (radicals), or a pair is shared (nucleophiles and electrophiles). It is the biggest topic in the course by a distance — SL 24 hours, HL 45 — and at HL it is a quarter of everything.
Assessment and the core
The scientific investigation is 20% of your grade and is marked on four criteria worth six marks each — which means research design is worth as much as your conclusion, and most lost marks are lost before any data is collected. The Extended Essay and the Collaborative Sciences Project sit outside the syllabus but inside your two years.
🧩How to use these pages
Every sub-topic page has the same shape: what you need to be able to do, then the chemistry broken into the syllabus understandings, a worked example, six practice questions with full answers, and a clearly separated list of other people’s resources.
Each worked example ends by naming the specific mistake that costs marks on that sub-topic — forgetting that the water absorbs the heat and not the reaction, cancelling a state symbol out of an equilibrium expression when it should stay, drawing the SN2 transition state with five bonds. Those paragraphs are the most useful part of the page and the easiest to skip.
Where a sub-topic connects to another, the link is in the text. Follow them. The syllabus is built around linking questions, and Paper 2 routinely starts in one place and finishes somewhere else entirely.
🎓Official IB resources
These are the documents that actually govern the course. Your school has access to all of them through the Programme Resource Centre, so ask your teacher — or me — if you cannot reach one.
- The Chemistry guide (first assessment 2025) — the definitive statement of what can be asked. Each understanding is numbered, and anything not there is not examinable.
- The Chemistry data booklet — you get a clean copy in every paper. Learn what is in it now, so you stop memorising things you will be given.
- Specimen papers and markschemes — written for this syllabus, unlike most of the past papers you will find online.
- Subject reports — examiners describing, in plain language, exactly what candidates got wrong last session. Almost nobody reads them.
📜A note on past papers
Past papers are the most valuable revision in this subject, and your school can give you properly licensed ones. Two cautions when you use them.
First, anything from 2024 or earlier is the old syllabus. Much of it is still perfectly good practice — a mole calculation does not change — but the option topics, the old Paper 3 and several old understandings are gone, and some current material was never examined before 2025. Use old papers for skills, current specimens for format.
Second, mark your own work against the markscheme rather than against a model answer. IB markschemes award specific points, often with ORA (or reverse argument) and OWTTE (or words to that effect) attached, and you cannot see which points you missed by comparing prose.