Overview
IB Chemistry has changed. The current syllabus was first taught from 2023 with first examinations in May 2025, and three structural shifts stand out: the course is now concept-based, organised around two big ideas — *Structure* and *Reactivity* — instead of a long list of separate topics; the old optional topics have been removed entirely; and assessment is streamlined to two exam papers rather than three. If your picture of IB Chemistry comes from an older sibling or an out-of-date revision site, this guide gets you current. The underlying chemistry has not changed — but how it is framed, and how you are examined on it, has.
The headline changes at a glance
The rest of this guide unpacks each of these and what they mean for how you should revise. For exact paper timings, mark allocations, and weightings, always check the official IB subject guide or ask your teacher for the definitive current structure — those specifics are the sort of thing that gets misquoted online, so go to the source.
| Area | Old syllabus | New (2025) syllabus |
|---|---|---|
| Syllabus structure | Topic-by-topic list (atomic structure, bonding, energetics… as separate units) | Concept-based, organised under two themes: Structure and Reactivity |
| Options | Optional topics chosen from a menu, assessed separately | Removed — one common body of content, no options |
| Exam papers | Three papers (the third covered the options) | Two papers (Paper 1 and Paper 2) |
| Focus | Coverage of discrete topics | Connections between models, patterns, and reactions |
The new Structure + Reactivity framework
For the IB Diploma Programme, the most fundamental change is philosophical. Instead of marching through numbered topics, the syllabus now hangs everything on two organising concepts, each split into three strands:
Structure — the make-up of matter:
- S1 — models of the particulate nature of matter (atoms, isotopes, the mole, electron configuration).
- S2 — models of bonding and structure (ionic, covalent, metallic bonding; intermolecular forces; how structure explains properties).
- S3 — classification of matter (the periodic table and periodicity, organic families, spectroscopic identification).
Reactivity — how and why matter changes:
- R1 — what drives reactions (energetics: enthalpy, and for HL entropy and Gibbs free energy).
- R2 — how much, how fast, and how far (stoichiometry, kinetics, and equilibrium together).
- R3 — what are the mechanisms of chemical change (proton transfer / acid–base, electron transfer / redox, and organic mechanisms).
The point of this reorganisation is to make the connections explicit. Bonding (S2) is no longer a box you tick and forget — it is the thing that explains boiling points, solubility, and mechanism, so it keeps reappearing across Reactivity. Studying by isolated topic worked well enough on the old syllabus; on this one it works against you, because the exam rewards students who move fluidly between a structural idea and its consequences for reactivity.
Options removed — what it means
For the IB Diploma Programme, on the previous syllabus your class picked an optional topic from a menu, studied it in addition to the core, and answered on it in a dedicated paper. That is gone. The 2025 syllabus is a single common body of content that every candidate studies — no options, no menu, no separate option paper.
What this means in practice:
- Everyone sits the same content, so there is no longer a "we did the medicinal chemistry option, they did energy" divide between schools.
- Less content sprawl. Material that used to live in options has, where retained, been folded into the main concepts rather than bolted on separately.
- Simpler revision planning. No hunting for past papers on one specific option or worrying that yours is under-resourced online.
If you find old resources labelled "Option A/B/C/D" or "Paper 3 options," treat them as out of date for exam structure — though the underlying chemistry can still be useful practice.
The streamlined assessment
For the IB Diploma Programme, assessment now runs on two written papers instead of three:
- Paper 1 contains a multiple-choice section and a data-based section — recall, quick application, and interpreting given data.
- Paper 2 contains short-answer and extended-response questions — full calculations, "state and explain" answers, and structured problems marked point-by-point on method and accuracy.
The third paper from the old structure, which existed largely to assess the options, is no longer part of the course — a genuine simplification, with a clearer split between the "know it / read the data" work of Paper 1 and the "work it through and explain it" work of Paper 2.
Because exact timings and weightings are the details most often mis-stated by third-party sites, confirm the current numbers in the official IB subject guide or with your teacher rather than trusting any figure quoted second-hand. For how each paper is marked and where the marks are won, see how to get a 7 in IB Chemistry.
What stayed the same
For the IB Diploma Programme, it is easy to over-panic about a syllabus change. Plenty is unchanged:
- The internal assessment is still the individual scientific investigation — your own experimental inquiry, criterion-marked, worth planning early.
- SL and HL still share a common core, with additional higher level (AHL) content layered on for HL. The extra HL depth (entropy and Gibbs free energy, more demanding equilibrium and organic work) sits on top of the same concepts. If you are still deciding, read IB Chemistry SL vs HL.
- The actual chemistry — moles, bonding, energetics, kinetics, equilibrium, acids and bases, redox, organic mechanisms — is the same science it always was.
- "Skills in the study of chemistry" — practical tools, inquiry, and nature-of-science thinking — run through the whole course rather than being a bolt-on unit.
So the map is redrawn, but most of the territory is familiar.
What this means for your revision
For the IB Diploma Programme, the single biggest mindset shift: revise connected concepts, not isolated topics. A few concrete habits follow from the concept-based design:
- Anchor everything to Structure or Reactivity. When you learn a fact, ask which concept it serves and what it lets you predict — bonding is a tool for explaining reactivity, not trivia.
- Practise crossing strands. Real exam questions link structure (say, S2 intermolecular forces) to a property or reaction outcome. Drill those bridges deliberately.
- Do not chase deleted options, and prepare two paper styles, not three — fast recall and data reading for Paper 1; full working, units, and reasoned explanations for Paper 2.
How to study the new syllabus
For the IB Diploma Programme, a simple weekly loop beats cramming:
- Learn one concept strand at a time — take S2 or R2 as a unit and understand it before drilling questions.
- Practise timed, mixed questions that force you to connect strands, with the data booklet open so navigating it becomes automatic.
- Mark honestly and log dropped marks by type — units, sig figs, method, vague explanation — then attack your recurring errors before the next session.
Start your scientific investigation IA early rather than in the final term, and use the IB guides hub to structure the run-in. For paper-by-paper practice, the IB Chemistry SL past papers guide shows how to use them well.
How MarkScheme helps
MarkScheme's chemistry courses are built on the 2025 syllabus, mapped to the Structure and Reactivity concepts rather than the old topic list — no filtering out deleted options or second-guessing whether a resource is current. Work through the [IB Chemistry SL course](/ib/courses/chemistry-sl) or the [HL course](/ib/courses/chemistry-hl), then [get an answer marked](/mark) against IB-style criteria so your extended Paper 2 responses get examiner-shaped feedback before the real thing.
Frequently asked questions
This section covers Frequently asked questions — what IB examiners reward most often in past papers and coursework.
When are the first exams for the new IB Chemistry syllabus?
The current syllabus was first taught from 2023, with first examinations in May 2025. If you are sitting Chemistry in 2025 or later, this is your syllabus.
Are there still options in IB Chemistry?
No. The optional topics from the previous syllabus have been removed. Every candidate now studies one common body of content, and there is no separate options paper.
How many exam papers are there now?
Two — Paper 1 (a multiple-choice section plus a data-based section) and Paper 2 (short-answer and extended-response questions). The old third paper, which mainly assessed the options, is gone. For exact timings and weightings, check the official IB subject guide or ask your teacher.
Is the internal assessment different?
The IA is still the individual scientific investigation — your own experimental inquiry, criterion-marked. It remains a significant, controllable chunk of your grade, so start it early.
Do SL and HL still share content?
Yes. SL and HL share a common core, with additional higher level (AHL) content for HL that adds depth (entropy and Gibbs free energy, more demanding equilibrium and organic work). See IB Chemistry SL vs HL if you are choosing.