When we get a change in syllabus it can be pretty overwhelming to work out which concepts are old syllabus (so you shouldn’t stress about them) and which concepts are new syllabus (so you won’t see questions on them but you should stress about them!).
The red highlighted sections are big new concepts to the new syllabus and I strongly recommend you spend time on these.
Are you an HL student? Make sure you read the SL and the HL sections.
I’ve done my best to make this document as complete as possible but please message me at missparkerchem@gmail.com if you spot any issues or missing concepts. This page will be updated regularly so I recommend not downloading and just checking back here when you want to check something.
Still not feeling confident?
New concepts for the 2025 exams
New concepts in SL
S2.2.8 Dipole-induced dipole – this term wasn’t in the last syllabus
S2.2.10 Chromatography – Make sure you review this as a method of separation, an experimental technique (with common issues and improvements) and how to interpret results including calculation of Rf.
S2.4 Bonding triangle This model for the spectrum of types of bonding is completely new. Practice using the bonding triangle and consider the pros and cons of different ways of determining type of bonding.
S2.4.4 Common properties of plastics in terms of structure – it wasn’t explicitly expected for you to know an example of a natural and a synthetic polymer
S3.2.2 Functional groups to know: halogeno, hydroxyl, carbonyl, carboxyl, alkoxy, amino, amido, ester, phenyl (removed alkyl, alkenyl, alkynyl, nitrile . Added halogeno . Changes: ether -> alkoxy, carboxyamide → amide. ) You’ll see these a bunch in past paper questions so be careful of assuming “correct” answers will be correct in new syllabus.
S3.2.3 Change of key term – “class” of compound now called homologous series e.g. alkanes, alkenes, alkynes, halogenoalkanes, alcohols, aldehydes, ketones, carboxylic acids, ethers, amines, amides and esters. (removed nitrile and arene)
S3.2.6 IB now uses more specific terminology for isomers – branched, straight-chain, position and functional group isomers. I recommend ensuring you know what each of these mean
R1.1.3 – axis labels for energy level diagrams more specific now. Must be reaction coordinate x , potential energy y – more options used to be accepted in mark schemes
R1.3.3 fossil fuels Evaluation of fossil fuels is new to the syllabus. Review the pros and cons of each type and how the release of CO2 leads to the greenhouse effect.
R1.3.4 bio fuels Review the pros and cons of biofuels and be comfortable interpreting data on them.
R1.3.5 fuel cells – Memorise the hydrogen and methanol fuel cells including being able to deduce the half equations.
R2.1.5 atom economy – Know how atom economy can be used as a measure of efficiency of a reaction and how to calculate it.
R2.2.2 “the role of collision geometry” – check you know what this means, it’s new
R2.3.2 – K – equilibrium constant used to be Kc – this means exactly the same just a change in notation
R3.1.1 The distinction between the terms “base” and “alkali” should be understood. – now explicitly expected in syllabus
R3.1.6 strong acids – HCl, HBr, HI, HNO3 H2SO4 – know that these are strong acids – HBr and HI are new to this list. Also know that all group 1 hydroxides are strong bases.
R3.1.7 – this syllabus statement is more specific in terms of acid-base reactions you’re expected to know. The inclusion of amines as a base is new and I would check if you know how to answer – acid + amine → salt + water – type questions.
R3.1.8 -pH curve for strong acid- strong base is new to SL
R3.2.7 rechargeable cells – secondary cells – know how these work and to be able to compare to primary (voltaic cells) and fuel cells in terms of pros and cons.
R3.2.9 – know experimental set up and explanation for oxidation of alcohols – this is now explicit in the syllabus although you may see some questions on this, it is now expected knowledge why you might choose distillation or heating at reflux.
R3.2.10 Reduction of carboxylic acids/aldehydes/ketones – new to SL syllabus
R3.4.2 Basic mechanism for nucleophilic substitution – new to SL syllabus
R3.4.1/3 Recognition of nucleophiles and electrophiles – new to SL syllabus
R3.4.5 reactions of alkenes now described as “Electrophilic addition” which is new to SL (used to just be addition – you will not score points for this now, IB are trying to incorporate use of nucleophile and electrophile concepts)
New concepts in HL
S2.4.6 Condensation polymerisation-be able to identify condensation polymers, and draw polyamides and polyesters from monomers. Also recommend knowing about the hydrolysis of condensation polymers with water.
S3.1.7 Explanation for discontinuities in first ionization energy – explanations will not accept “special stability” of filled/half-filled sublevels – this used to be accepted in some answers so check you know how to answer this correctly
R1.2.4 equations for enthalpy changes using enthalpy of combustion/formation now in data booklet
R1.4.4 Lots more material on dG and equilibrium. The equation linking dG and Q is new. Worth reviewing this concept since you won’t find many questions on this in past paper Q.
R2.2.2 “the role of collision geometry” – check you know what this means, it’s new
R3.1.17 Calculation of pH of buffers and effect of dilution on buffers -Understand and explain how buffers work using equations. Review how to calculate pH and how diluting buffers affects the buffer capacity.
Concepts that have been removed from the syllabus
Feel free to message me @chem.jungle if you have any questions about any of these or want more clarification
Concepts no longer in SL
Resonance structures removed from SL
R1.2.3 calculation of enthalpy of formation and combustion removed from SL. SL only need to be able to use Hess’ Law for multistep reactions
Amphiprotic- this term is no longer used in the syllabus – but the concept of things that can behave as both acids and bases (e.g. water) will still show up.
S3.1.5 Acid rain – lots of content about acid rain / pre/post combustion removal of acidic emissions has been removed from the syllabus – now just need to know just basic equations of formation of acid rain and how ocean acidification happens due to increasing CO2 in the atmosphere.
S3.2.6 No longer expected to name ethers or esters.
Esterification – formation of esters removed
R3.2.7 – no longer need to know specific oxidising agents for alcohols – ignore questions that expect you to know acidified potassium dichromate etc
Winkler method to determine biochemical oxygen demand – when you see questions on this it is no longer in syllabus but could still be used as a back titration application question, so might be worth attempting if you’re aiming for a 7.
Activity series removed from data booklet – they’ll just give you data to deduce activity series if required
Removal of ppm as a unit of concentration – only need to convert mol dm-3 and g dm-3
S3.1.2 removed knowledge of position of lanthanoids and actinoids in periodic table
Interpretation of mass spectrums of compounds has been removed from SL (could still be expected to interpret mass spec of an element).
Interpretation of infrared spectra of compounds has been removed from SL
Interpretation of NMR (nuclear magnetic resonance) of compounds has been removed from SL
Calculation of IHD value removed.
Concepts no longer in HL
S3.2.7 Change of term : no longer using conformational and configurational isomers – IB now using exclusively cis-trans/optical as well as branched, straight-chain, position and functional group isomers.
S3.2.7 E/Z isomers removed.
S3.2.10 Removed explanation of TMS (tetramethylsilane) as the reference standard for NMR
S3.2.10 Removed X-ray crystallography
R1.2.5 Construction of a born haber cycle no longer expected
R1.2.5 Removed enthalpy of hydration and solution – also not expected to construct cycles with these
R3.2.10 Reduction of carboxylic acids/aldehydes/ketones no longer need specific reagents, just use of hydride ions
Winkler method to determine biochemical oxygen demand – when you see questions on this it is no longer in syllabus but could still be used as a back titration application question, so might be worth attempting if you’re aiming for a 7.
R3.2.10 Removed explanation of the solvent in nucleophilic substitution and the knowledge of how the reaction mechanism affects the rate.
R3.4.13 Electrophilic substitution of benzene -used to be nitration of benzene, now replaced with general electrophile E+. Formation of the nitronium ion removed. Also reduction of nitrobenzene to phenylamine was removed.
S3.1.8 Different types of magnetism for transition elements removed – paramagnetism/diamagnetism/ferromagnetism
R3.4.8 – Ligands – now only need basic knowledge of ligands. Removed monodentate/bidentate/polydentate ligands, how they affect the splitting of the d-orbitals (spectrochemical series)
Removed explanation of the wavelength of light required to dissociate oxygen and ozone (although this could come up as an application questions – i.e. higher energy (stronger) bonds in ozone require lower wavelength/high freq of radiation to break) and Description of the mechanism of the catalysis of ozone depletion when catalysed by CFCs and NOx.
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