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Major changes for the 2023 programme

Major changes in the 2023 Guide (first exams May 2025) compared with the 2014 Guide (last exams November 2024)

Introduction

If you are teaching the IB Diploma programme for the first time then the changes from the 2014 Guide are not so relevant, even so, it may be useful when it comes to using past examination questions (from May 2016 until November 2024). Most IB Diploma chemistry teachers however will be familiar with the syllabus based on the 2014 Guide and many will be teaching both syllabuses at the same time during the changeover year. Although the chemistry content in the 2023 Guide has been reduced considerably there are some major changes which are perhaps not so immediately obvious, principally because of the way in which the syllabus is now set out. The aim of this page is to highlight these major changes (click on the + button to open up each heading) but in order to keep it to a manageable size it cannot be comprehensive. For definitive information you should consult the IB Diploma 2023 Chemistry Guide together with any other official IB publications. You might like to also watch a YouTube video produced by the IB which provides some further insights into the new course.

Underlying philosophy

The new 2023 Guide lists nine aims which broadly reflect the ten aims of the 2014 Guide. The biggest difference is with the first aim which is to “develop conceptual understanding that allows connections to be made between different areas of the subject, and to other DP sciences subjects”. This provides the rationale for listing the syllabus in just two strands “Structure” and “Reactivity” rather than the previous way of listing the eleven (twenty one for HL) main topic areas in the 2014 Guide. However it seems strange that "students are expected to examine scientific knowledge claims in a real-world context, fostering interest and curiosity" and yet almost the content in all the options material from the 2014 guide which addressed much of the real world context is not present in the 2023 guide, neither are there any references to other IB science subjects. The Nature of Science and International-mindedness etc. are still an integral part of the course but the term "Utilization" is no longer on the syllabus.

External assessment

There are still four assessment objectives upon which both the external and internal assessment are based. The wording of each objective has changed between the two guides but essentially there are no major changes to the objectives.

The time for the external examination papers remains the same (SL: 3 hours; HL 4.5 hours) but there are now only two examination papers for each level. As before all the questions should be attempted (there is no choice). Note that unlike the 2014 programme students can use a calculator and will have access to a clean copy of the whole IB data booklet for all of Paper 1 (i.e. for the multiple choice questions as well as for Section B).

Paper 1: Total time 1.5 hours; total raw mark 55; component weighting 36%

      In two booklets completed together without interruptions on SL level material only

Section A: 30 multiple choice questions (30 marks)

Section B: Data-based & experimental work questions  (25 marks)

      Paper 2: Total time for paper 1.5 hours, total raw mark 50, component weighting 44%

      Short-answer and extended-response questions on standard level material only

Paper 1: Total time 2 hours; total raw mark 75; component weighting 36%

      In two booklets completed together without interruptions on SL and AHL material 

Section A: 40 multiple choice questions (40 marks)

Section B: Data-based & experimental work questions  (35 marks)

      Paper 2: Total time for paper 2.5 hours, total raw mark 90, component weighting 44%

      Short-answer and extended-response questions on SL and AHL material

Internal assessment (IA)

The internal assessment research work is now called "The scientific investigation" (in the previous 2014 Guide it is called "The individual  scientific investigation). It is the third assessment component and still counts 20% towards the overall assessment (with the external assessment making up the remaining 80%).

The allocated time of 10 hours remains unchanged but now there is more scope for students to collaborate with one or two other students, if they wish. This means that they are able to share similar methodologies, provided that the independent or dependent variables differ, and the data collected is unique to each student so that each student has their own individual research question.

The maximum overall word count for the written report is 3,000 words and the 2023 guide gives guidance as to what counts as a word. (The 6-12 pages etc. guidance in the 2014 Guide has now gone).

The report is now assessed on four, not five, criteria. The four criteria have equal weighting. Each is worth 6 marks to still give a maximum raw mark of 24 which the IB scales to give the 20% IA weighting. The four new criteria are Research design, Data analysis, Conclusion and Evaluation and there are new level descriptors for assigning the marks. The equal weighting for each criteria now means that a greater emphasis is placed on higher-order thinking skills with 50% of the marks allocated for Conclusion and Evaluation.

Practical scheme of work

There is no change to the hours (SL 40 hours; HL 60 hours) and the form "Record of experimental programme" which replaces the old form 4/PSOW) still includes 10 hours for the Scientific investigation and 10 hours for what was the Group 4 project but which is now called the Collaborative sciences project. The PSOW should provide opportunities for students to practise the tools, techniques and the Inquiry process listed under skills (see next heading) to complement their coverage throughout the whole of the course. Unlike the 2014 Guide there are no mandatory areas to be covered.

Skills in the study of chemistry

Although required mathematical skills and ICT skills are listed in the 2014 Guide this is essentially a brand new addition to the 2023 Guide which sets out the required skills much more clearly. None of the 110 hours (SL) or 180 hours (HL) time for teaching the syllabus  is allocated specifically to covering these listed skills, but they can (and will) be assessed both externally and internally. The skills cover Tools: Experimental techniques, and Technology & Mathematics and the Inquiry process: Exploring & designing, Collecting & processing data and Concluding & evaluation. Make sure you familiarise yourself with all these required skills which are listed on pages 27 to 32 of the 2023 Guide.

Data booklet

Unfortunately I cannot put a link to the data booklet here as it is copyright IBO but you can download it yourself from the resources section of My IB.The data booklet for first exams 2025 is considerably smaller (23 sections compared to 38 sections for the first exams 2016 data booklet). This is principally because there are no longer options on the syllabus. New (or altered sections) include 2. Physical constants (which now include elementary masses), 3. Metric (SI) multipliers and 4. Unit conversions and standard conditions (STP and SATP conditions are now 273.15 K and 100 kPa; and 298.15 K and 100 kPa respectively compared to 273.15 K and 100 kPa; and 298.15 K and 100 kPa in the 2016 Data booklet). Note that what were Sections 21 and 25 respectively in the 2016 Data booklet, 'The strengths of organic acid and bases' and 'The activity series' are among the sections that have now disappeared.

The syllabus content SL/HL and AHL

As far as delivering the new programme goes this is where the major change occurs. The syllabus is set out in a completely different way so it is not so easy to see what is new, what has been retained unaltered, what has been altered slightly and what has been completely removed compared to the 2014 Guide.  Some of the new sub-topics contain material from more than one of the 2014 topics.  There is no longer a "core" and options. The four separate options in the 2014 Guide have completely gone and very little of the chemistry covered specifically in those options has been retained. The 11 (SL) or 21 (SL & HL) topics headings making up the "core" and AHL have gone and now the syllabus content is set out under just two main strands "S: Structure" and "R: Reactivity" to emphasise the importance of conceptual understanding. Each strand is broken down into sub-topics with a guiding question and these are further broken down into understandings. These show the content and outcomes of teaching and learning together with any clarifications and suggested guiding questions to make links to other sub-topics. At the end of each sub-topic any AHL material is then added.

An example of how the syllabus is set out

Because the new strands often overlap with material in different topics and sub-topics from the 2014 Guide it is difficult to compare the suggested teaching times, but generally there seems more time to cover the content of the 2023 syllabus compared to the 2014 syllabus.

Additions to the 2023 chemistry syllabus not in 2014 Guide

The list below contains the main additions to each heading that are completely absent from anywhere in the core/AHL in the 2014 Guide - for content in the 2014 Guide that is no longer assessed (i.e. absent from the 2023 Guide) see the next heading 'Material in 2014 Guide not included in 2023 Guide'.

S1 Models of the particulate nature of matter

S1.1 - Introduction to the particulate nature of matter

Specifies that solvation, filtration, recrystallization, evaporation, distillation and paper chromatography should be covered.

S1.2 - The nuclear atom

Mass spectrometer is only required at HL, not SL

S1.3 - Electron configurations

Frequency is now f not ν, i.e. E = hf not E = hν.

S1.4 - Counting particles by mass: The mole

Avogadro's constant is now only represented by NA (not NA, or L)

S1.5 - Ideal gases

No additions

S2 Models of bonding & structure

S2.1 - The ionic model

Binary ionic compounds are named with the cation first, followed by the anion. The anion adopts the suffix "ide".
Names are given for the listed polyatomic ions.
Include lattice enthalpy as a measure of the strength of the ionic bond in different compounds, influenced by ionic radius and charge.

S2.2 - The covalent model

Lewis formula now used instead of Lewis structure.
Coordination bond now used instead of coordinate covalent bond.
Chromatography is a technique used to separate the components of a mixture based on their relative attractions involving intermolecular forces to mobile and stationary phases.
Explain, calculate and interpret the retardation factor values, RF.
AHL Sigma and pi bonding now only described in terms of 'combination' of atomic orbitals rather than 'overlap'.

S2.3 - The metallic model

Note that alloys are covered in S2.4.
AHL Transition elements have delocalized d-electrons.
Explain the high melting point and electrical conductivity of transition elements.

S2.4 - From models to materials

Understanding and using the bonding triangle to explain properties of materials (only covered in Option A in the 2014 Guide).
AHL Condensation polymerisation (only covered in Option A in 2014 Guide).

S3 Classification of matter

S3.1 - The periodic table: Classification of elements

Periodicity is now stated to refer to trends in properties of elements across a period and down a group.
Deduce equations for the reactions with water of the oxides of group 1 and group 2 metals, carbon and sulfur. (Changed from "Construction of equations to explain the pH changes for reactions of Na2O, MgO, P4O10, and the oxides of nitrogen and sulfur with water.")
Include acid rain caused by gaseous non-metal oxides, and ocean acidification caused by increasing CO2 levels. (Acid deposition is covered in Topic 8 in the 2014 Guide but there is no mention of ocean acidification.)
The terms “oxidation number” and “oxidation state” are often used interchangeably, and either term is now acceptable in assessment.
Naming conventions for oxyanions use oxidation numbers shown with Roman numerals, but generic
names persist and are acceptable. Examples include NO3– nitrate, NO2–   nitrite, SO42– sulfate and SO32– sulfite.

S3.2 - Functional groups: Classification of organic compounds

Emphasis on names of functional groups and homologous series rather than on names of classes and functional groups. Halogeno and amido added to names of functional groups.
Discussion of the structure of benzene using physical and chemical evidence is only now required at HL, not SL, (although phenyl, C6H5-,  is still included in the list of functional groups that need to be identified).
Recognize isomers, including branched, straight-chain, position and functional group isomers.

R1 What drives chemical reactions?

R1.1 - Measuring enthalpy changes?

Axes for energy profiles should be labelled as reaction coordinate x, potential energy y.
Heat evolved is now Q, not q, as in Q = mcΔT and the new equation ΔH = − Q/n in the calculation of the enthalpy change of a reaction.

R1.2 - Energy cycles

AHL Calculate enthalpy changes of a reaction using ΔHf⦵ or ΔHc⦵:
ΔH⦵ = ΣΔHf⦵(products) − ΣΔHf⦵(reactants) (in core of 2014 guide);  ΔH⦵ = ΣΔHc⦵(reactants) − ΣΔHc⦵(products) (not in 2014 guide)
The construction of complete Born-Haber cycles will not be assessed.

R1.3 - Energy from fuels

Evaluate the amount of carbon dioxide added to the atmosphere when different fuels burn.
Understand the link between carbon dioxide levels and the greenhouse effect (only covered fully in Option C in the 2014 Guide).
Understand the difference between renewable and non-renewable energy sources and consider the advantages and disadvantages of biofuels (only covered in Option C in the 2014 Guide).
Hydrogen and methanol fuels cells (only covered in Option C in the 2014 Guide).

R1.4 - Entropy & spontaneity (AHL only)

ΔG is now known as Gibbs energy (in the 2014 Guide it is Gibbs free energy).
Note the units: ΔH kJ mol−1;  ΔS J K−1 mol−1; ΔG kJ mol−1.
Perform calculations using the equation ΔG = ΔG⦵ + RT lnQ and its application to a system at equilibrium ΔG⦵ = −RT lnK. (The 2014 Guide only has the second equation given in Topic 17)

R2 How much, how fast and how far?

R2.1 - How much? The amount of chemical change

Calculate the atom economy from the stoichiometry of a reaction and include discussion of the inverse relationship between atom economy and wastage in industrial processes. (Atom economy is only covered in Options A and B in the 2014 Guide).

R2.2 - How fast? The rate of chemical change

Biological catalysts are called enzymes.
AHL Distinguish between intermediates and transition states, and recognize both in energy profiles of reactions.
Interpret the terms “unimolecular”, “bimolecular” and “termolecular”.
The constant A in the Arrhenius equation is now called the Arrhenius factor (in the 2014 Guide it is called the frequency factor or pre-exponential factor).

R2.3 - How far? The extent of chemical change

Equilibrium constant referred to throughout as K rather than Kc.
The equilibrium law describes how the equilibrium constant, K, can be determined from the stoichiometry of a reaction.
Le Châtelier’s principle can be applied to heterogeneous equilibria such as X(g) ⇄ X(aq).
Include the extent of reaction for: K<<1, K<1, K = 1, K>1, K>>1.
AHL The approximation [reactant]initial ≈ [reactant]eqm when K is very small should be understood.

R3 What are the mechanisms of chemical change?

R3.1 - Proton transfer reactions

The distinction between the terms “base” and “alkali” should be understood.
Amines added to the list of bases and organic acids added to the list of acids included for neutralization reactions.
Sketch and interpret pH curves for monoprotic neutralisation reactions involving strong acids and strong bases (only covered at HL in the 2014 Guide).
AHL Solve problems involving the composition and pH of a buffer solution, using the equilibrium constant (only covered in Options B and C in the 2014 Guide).

R3.2 - Electron transfer reactions

The relative reactivity of metals observed in metal/ metal ion displacement reactions does not need to be learned; appropriate data will be supplied in examination questions.
Secondary (rechargeable) cells involve redox reactions that can be reversed using electrical energy. Deduce the reactions of the charging process from given electrode reactions for discharge, and vice versa. (Secondary cells were only covered in Option C in the 2014 Guide).
Include discussion of advantages and disadvantages of fuel cells, primary cells and secondary cells.
Deduce equations to show reduction of carboxylic acids to primary alcohols via the aldehyde, and reduction of ketones to secondary alcohols (include the role of hydride ions in the reduction reaction). (Only covered at HL in the 2014 Guide).
Reduction of unsaturated compounds by the addition of hydrogen lowers the degree of unsaturation. (Degree of unsaturation replaces the term 'Index of hydrogen deficiency' in the 2014 Guide).
AHL The effects of concentration and the nature of the electrode are limited to the electrolysis of NaCl(aq) and CuSO4(aq).

R3.3 - Electron sharing reactions

The use of a single-barbed arrow (fish hook) to show the movement of a single electron.
The stability of alkanes is due to the strengths of the C−C and C−H bonds and their essentially non-polar nature.

R3.4 - Electron-pair sharing reactions

Explain, with equations, the formation of ions by heterolytic fission.
Recognize nucleophiles and electrophile (both neutral and negatively charged species) in chemical reactions.
The word 'substrate'. is used in a diagram
AHL Describe and explain the mechanism of the reaction between benzene and a charged electrophile, E+. (In the 2014 Guide this is limited to the nitration of benzene using NO2+ as the electrophile).

Skills

Although skills are not listed as part of the 'syllabus' in the 2023 Guide they can be assessed so are included here. They contain content covered in Topic 11, Mathematical requirements and the Internal Assessment in the  2014 Guide and the Use of ICT in the Teachers support material. Listed below are just the new skills under "Tools" not specifically mentioned anywhere in the 2014 Guide or 2014 TSM. The skills for the Inquiry process are essentially similar to those covered under Internal Assessment in the 2014 Guide.

Tools

T1 Experimental techniques

Understand how to accurately measure the following to an appropriate level of precision: mass, volume, time temperature, length, pH of a solution, electric current and electric potential difference.
Show awareness of the purpose and practice of: preparing a standard solution, carrying out dilutions, drying to constant mass, distillation and reflux, paper or thin layer chromatography, separation of mixtures, calorimetry, acid–base and redox titration, electrochemical cells, colorimetry or spectrophotometry, physical and digital molecular modelling, recrystallization and melting point determination.

T2 Technology

None

T3. Mathematics

Determine rates of change from tabulated data.
Calculate mean and range.
Appreciate when some effects can be ignored and why this is useful.
Compare and quote values to the nearest order of magnitude.
Understand direct and inverse proportionality, as well as positive and negative correlations between variables.
Distinguish between continuous and discrete variables.
Apply the coefficient of determination (R2) to evaluate the fit of a trend line or curve.
Draw and interpret uncertainty bars.
AHL Carry out calculations involving exponential functions

Material in 2014 Guide not included in 2023 Guide

The following no longer need to be learned.

Topic 1: Stoichiometric relationships

Parts per million (ppm) as a unit of concentration

Topic 2: Atomic structure
The mass spectrometer to determine the relative atomic mass of an element from its isotopic composition (no longer at SL).

Topic 3: Periodicity

The terms lanthanoids and actinoids.
Construction of equations to explain the pH changes for reactions of Na2O, MgO, P4O10, and the oxides of nitrogen and sulfur with water. (Changed to "Deduce equations for the reactions with water of the oxides of group 1 and group 2 metals, carbon and sulfur.")
Group trends should include the treatment of the reactions of alkali metals with halogens.

Topic 4: Chemical bonding & structure

Resonance structures occur when there is more than one possible position for a double bond in a molecule (no longer at SL).

Topic 5 - Energetics/thermochemistry

ΔH⦵ = ΣΔHf⦵(products) − ΣΔHf⦵(reactants) (moved to HL)

Topic 6: Chemical kinetics

None

Topic 7: Equilibrium

Determination of the relationship between different equilibrium constants, Kc for the same reaction (at the same temperature) when represented by equations written in different ways.
Relationship between Kc values for reactions that are multiples of one another.
Reaction quotient, Q (no longer at SL level, moved to HL).

Topic 8: Acids & bases

The difference between the terms amphoteric and amphiprotic.
The terms ionization and dissociation can be used interchangeably.
"Distinction between strong and weak acids in terms of the rates of their reactions with metals, metal oxides, metal hydroxides, metal hydrogen carbonates and metal carbonates. Strong and weak acids and bases also differ
in their electrical conductivities for solutions of equal concentrations." (Although this is still in the 2023 Guide as "The distinction between strong and weak acids or bases and concentrated and dilute reagents should be covered." it is no longer spelt out so clearly).
Balancing the equations that describe the combustion of nitrogen to its oxides and the subsequent formation of HNO2 and HNO3.
Distinction between the pre-combustion and post-combustion methods of reducing sulfur oxides emissions.
Deduction of acid deposition equations for acid deposition with reactive metals and carbonates.

Topic 9: Redox processes

The activity series ranking metals according to the ease with which they undergo oxidation.
Deducing of the feasibility of a redox reaction from the activity series.
The Winkler Method to measure biochemical oxygen demand (BOD), used as a measure of the degree of pollution in a water sample.

Topic 10: Organic chemistry

Phenyl is still present in the 2023 Guide as a functional group but arene is removed from homologous series. Nitrile and carboxamide removed from examples of functional groups.
Alcohols undergo esterification (or condensation) reactions with acids.
Discussion of the structure of benzene using physical and chemical evidence (now only at HL).
Benzene does not readily undergo addition reactions but does undergo electrophilic substitution reactions (now only at HL).

Topic 11: Measurement & data processing

All of 11.3 Spectroscopic identification of organic compounds at SL. (Note that this also includes the Index of hydrogen deficiency, IHD.)

Topic 12: Atomic structure

None

Topic 13: The periodic table—the transition metals

Zn is not considered to be a transition element as it does not form ions with incomplete d-orbitals.
Transition elements show an oxidation state of +2 when the s-electrons are removed.
Knowledge of different types of magnetism including explanation of the magnetic properties in transition metals in terms of unpaired electrons.
Explanation of the effect of the identity of the metal ion, the oxidation number of the metal and the identity of the ligand on the colour of transition metal ion complexes.
Explanation of the effect of different ligands on the splitting of the d-orbitals in transition metal complexes and colour observed using the spectrochemical series.
A list of polydentate ligands is given in the data booklet in section 16.

Topic 14: Chemical bonding & structure

Explanation of the wavelength of light required to dissociate oxygen and ozone.
Description of the mechanism of the catalysis of ozone depletion when catalysed by CFCs and NOx.

Topic 15: Energetics/thermochemistry

Calculation of enthalpy changes from dissolution energy cycles.
Relate size and charge of ions to hydration enthalpies.
Complete construction of Born-Haber cycles.
Perform lab experiments which could include single replacement reactions in aqueous solutions.
Enthalpies of aqueous solutions (section 19) and enthalpies of hydration (section 20) are given in the data booklet.

Topic 16: Chemical kinetics

The order of a reaction can be fractional in nature.
Name of the frequency factor (or pre-exponential factor) changed to the Arrhenius factor.

Topic 17: Equilibrium

The position of equilibrium corresponds to a maximum value of entropy and a minimum in the value of the Gibbs free energy. (Not specifically mentioned in the 2023 Guide but implied in the use of ΔG = ΔG⦵ + RT lnQ and ΔG⦵ = −RT lnK in R1.4).

Topic 18: Acids & bases

Calculations of pH at temperatures other than 298 K.

Topic 19: Redox processes
The standard hydrogen electrode (SHE) consists of an inert platinum electrode in contact with 1 mol dm−3 hydrogen ion and hydrogen gas at 100 kPa and 298 K. The standard electrode potential (E⦵) is the potential (voltage) of the reduction half-equation under standard conditions measured relative to the SHE. Solute concentration is 1 mol dm−3 or 100 kPa for gases. (Although the standard hydrogen electrode is still in the 2013 Guide these precise details are no longer listed.)
Determination of the relative amounts of products formed during electrolytic processes.

Topic 20: Organic chemistry

Difference between conformational and configurational isomers
E/Z isomerism
Distinction between optical isomers using a polarimeter.
Typical reducing agents are lithium aluminium hydride (used to reduce carboxylic acids) and sodium borohydride.
Explanation of why hydroxide is a better nucleophile than water.
Outline of the difference between protic and aprotic solvents.
SN2 reactions are best conducted using aprotic, polar solvents and SN1 reactions are best conducted using protic, polar solvents.
Conversion of nitrobenzene to phenylamine via a two-stage reaction.
All of 20.2 Synthetic routes (i.e. deduction of up to four step synthetic routes given starting reagents and the product(s) and retrosynthesis).

Topic 21: Measurement and analysis

Use of X-ray crystallography to identify the bond lengths and bond angles of crystalline compounds
Explanation of the use of tetramethylsilane (TMS) as the reference standard in 1H NMR.

Options
All the content on all four of the options except for some or all of the material on:
Atom economy (Options A & B)
Triangular bonding diagram (Option A)
Condensation polymerisation (Option A)
Buffer solution calculations (Options B & D)
Acid rain/deposition (Option C)
Greenhouse effect (Option C)
Biofuels, fuel cells and secondary voltaic cells (Option C)

Changes in terminology

2023 Guide

Scientific investigation

Collaborative sciences project

NA (Avogadro's constant)

f (frequency, e.g. c = fλ)

Lewis formula

coordination bond

amido

Gibbs energy change, ΔG

Arrhenius factor, A

Equilibrium constant generally referred to as K

Degree of unsaturation

2014 Guide

Individual scientific investigation

Group 4 project

NA or L (Avogadro's constant)

ν (frequency, e.g. c = νλ)

Lewis structure

coordinate bond

carboxamide

Gibbs free energy change, ΔG

The frequency factor (or pre-exponential factor), A

Equilibrium constant generally referred to as Kc

Index of hydrogen deficiency, IHD

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