IB Diploma Programme Chemistry: Syllabus Guide

This guide covers the full syllabus structure of IB Diploma Programme Chemistry, first assessment 2025, for both Standard Level (SL) and Higher Level (HL) students. It complements the subject overview and the assessment revision notes already on the site by listing what is actually taught – the six numbered syllabus components, split across two strands: Structure and Reactivity.

Recommended teaching time for syllabus content is 110 hours at SL and 180 hours at HL, on top of a 40-hour (SL) / 60-hour (HL) experimental programme covering practical work, the collaborative sciences project and the scientific investigation.

Structure 1 – Models of the particulate nature of matter (17 hours SL / 21 hours HL)

• Structure 1.1 – Introduction to the particulate nature of matter, the foundational model everything else in the syllabus builds on.
• Structure 1.2 – The nuclear atom, including sub-atomic particles and isotopes.
• Structure 1.3 – Electron configurations, and how electron arrangement explains chemical behaviour.
• Structure 1.4 – Counting particles by mass: the mole, the quantitative bridge between mass and particle number.
• Structure 1.5 – Ideal gases, and the relationships between pressure, volume, temperature and amount.

Structure 2 – Models of bonding and structure (20 hours SL / 30 hours HL)

• Structure 2.1 – The ionic model – bonding through electron transfer between metals and non-metals.
• Structure 2.2 – The covalent model – bonding through shared electron pairs.
• Structure 2.3 – The metallic model – bonding through delocalised electrons.
• Structure 2.4 – From models to materials – how these three bonding models explain real material properties.

Structure 3 – Classification of matter (16 hours SL / 31 hours HL)

• Structure 3.1 – The periodic table: classification of elements, and how position predicts properties.
• Structure 3.2 – Functional groups: classification of organic compounds by their reactive groups.

Reactivity 1 – What drives chemical reactions? (12 hours SL / 22 hours HL)

• Reactivity 1.1 – Measuring enthalpy change, the energy released or absorbed by a reaction.
• Reactivity 1.2 – Energy cycles in reactions, using indirect routes to calculate enthalpy changes that cannot be measured directly.
• Reactivity 1.3 – Energy from fuels, applying enthalpy concepts to real combustion contexts.
• Reactivity 1.4 – Entropy and spontaneity (Additional higher level – HL only), explaining why some reactions occur without being driven by energy release alone.

Reactivity 2 – How much, how fast and how far? (21 hours SL / 31 hours HL)

• Reactivity 2.1 – How much? The amount of chemical change, using stoichiometry to quantify reactions.
• Reactivity 2.2 – How fast? The rate of chemical change, and the factors that speed up or slow down reactions.
• Reactivity 2.3 – How far? The extent of chemical change, covering equilibrium and how far a reaction actually proceeds.

Reactivity 3 – What are the mechanisms of chemical change? (24 hours SL / 45 hours HL)

• Reactivity 3.1 – Proton transfer reactions – acid-base chemistry.
• Reactivity 3.2 – Electron transfer reactions – redox chemistry.
• Reactivity 3.3 – Electron sharing reactions – radical chemistry: homolytic fission and free-radical substitution, with its initiation, propagation and termination stages, shown using half-headed (single-barbed) arrows that move one electron.
• Reactivity 3.4 – Electron-pair sharing reactions – organic reaction mechanisms built on shared electron pairs, together with Lewis acid-base reactions, coordination bonds and the formation of transition-element complexes.

Reading the Structure / Reactivity split

The syllabus deliberately separates two different kinds of chemical question: Structure asks “what is matter built from and how is it arranged?”, while Reactivity asks “why and how does matter change?”. Reactivity 3, on reaction mechanisms, is both the largest single component by hours and the one that draws most heavily on everything in Structure 1 and 2 – you cannot reason about electron-transfer or electron-sharing mechanisms without a secure grip on electron configurations (Structure 1.3) and bonding models (Structure 2).

How to approach it

Revise Structure and Reactivity as two parallel tracks rather than strictly in numerical order, and explicitly practise moving between them: a question on entropy and spontaneity (Reactivity 1.4, HL only) will expect you to already reason fluently about particle behaviour from Structure 1. Because Paper 1B and Paper 2 draw on data-based and experimental-work questions across the whole syllabus, treat the six components as one connected model of matter and its changes, not six separate topics to revise in isolation. HL students should track the extra hours and named HL-only content carried by all six components (Structure 1: 17 to 21 hours; Structure 2: 20 to 30 hours; Structure 3: 16 to 31 hours; Reactivity 1: 12 to 22 hours, including entropy and spontaneity; Reactivity 2: 21 to 31 hours; Reactivity 3: 24 to 45 hours) since these are where SL-level revision habits most often under-prepare HL candidates.

Reactivity 3, on reaction mechanisms, is worth extra attention simply on teaching-hours grounds – at 24 hours SL and 45 hours HL it is the single largest component in the whole syllabus, though not by a wide margin: at SL the next largest is Reactivity 2 at 21 hours, and at HL Structure 3 and Reactivity 2 are both close behind at 31 hours each. Because it draws together proton transfer, electron transfer and two different modes of electron sharing, it also tends to be where students who have revised Structure and Reactivity 1-2 in isolation discover gaps: mechanism questions routinely expect fluent recall of bonding models from Structure 2 and periodic trends from Structure 3 applied on the spot, not as separately memorised facts. Building a habit of asking “what bonding model explains this mechanism” every time you meet a new reaction type in Reactivity 3 is one of the most efficient ways to revise this component, since it forces the cross-referencing the exam itself rewards.

Official syllabus

International Baccalaureate Organization, Chemistry guide, Diploma Programme, first assessment 2025 (published February 2023, updated May 2023) – copy consulted via a school-hosted mirror, not ibo.org.