A-Level Chemistry Year 2 Curriculum: No Optional Topics; A Chapter-by-Chapter Look at Cambridge Chapters 23–37 and Edexcel Units 4 and 5

First, a quick note: A-Level Chemistry has no optional topics. The A Level section of Cambridge 9701 (Chapters 23–37) is entirely compulsory, and all six units of Edexcel IAL are also mandatory. In our article on How A-Level Chemistry is Tested, we only listed the chapter names for the A Level section; for practical and calculation questions, see Articles 183 and 197. This article breaks down what is covered in the second year (A Level stage) chapter by chapter: Cambridge Chapters 23–37 and Edexcel Units 4 and 5, followed by a comparison of the differences between the two exam boards. The content is based on the Cambridge 9701 (2025–2027) and Pearson IAL Chemistry syllabuses.

1. Which Papers Are Taken in the Second Year

• Cambridge: Paper 4 A Level Structured Questions (2 hours, 100 marks, 38.5% of A Level, also draws on AS knowledge) and Paper 5 Planning, Analysis and Evaluation (1 hour 15 minutes, 30 marks, 11.5%);
• Edexcel: Units 4 and 5 are each 1 hour 45 minutes long and worth 90 marks, each accounting for 20% of the IAL. They can be taken in January, June, or October. Each paper is divided into three sections: Section A (multiple-choice), Section B (structured questions), and Section C (data or calculation questions in Unit 4; contemporary context questions in Unit 5). A data booklet is required. At least 22 marks in Unit 4 and 18 marks in Unit 5 assess Level 2 or above mathematical skills. There may be synoptic questions requiring knowledge from previous units. For the Unit 6 practical unit, see Article 183.

2. Cambridge A Level: Physical Chemistry (Chapters 23–26)

• Chapter 23 Chemical Energetics: Enthalpy of atomization, lattice energy, first electron affinity (and trends in Groups 16 and 17); Born-Haber cycles (limited to +1, +2 cations and −1, −2 anions); energy cycles for enthalpy of solution and enthalpy of hydration; effects of ionic charge and radius on lattice energy and enthalpy of hydration; definition of entropy and determining the sign of entropy change, calculating ΔS using standard entropies (ΔS = ΔS_surroundings + ΔS_system is not required); Gibbs free energy ΔG = ΔH − TΔS, predicting reaction feasibility and the effect of temperature;
• Chapter 24 Electrochemistry: Predicting electrolysis products; F = Le; Q = It and calculating the mass and volume of electrolysis products; determining Avogadro's constant by electrolysis; standard electrode potentials and the standard hydrogen electrode; cell potential, electrode polarity, and direction of electron flow; predicting reaction feasibility and redox strength; qualitatively predicting electrode potential changes from concentration, and quantitative calculations using the Nernst equation; ΔG = −nE°F;
• Chapter 25 Equilibria: Conjugate acid-base pairs; calculating pH, Ka, pKa, and Kw (Kb is not tested); pH of strong acids, strong bases, and weak acids; preparation, principles, and pH calculations of buffer solutions, and the role of HCO₃⁻ in blood; solubility product Ksp and the common ion effect; partition coefficient;
• Chapter 26 Reaction Kinetics: Rate equations (orders of 0, 1, 2 for each substance); determining order using concentration-time graphs, initial rates method, and half-life method; half-life of first-order reactions is independent of concentration, k = 0.693/t½; deducing the mechanism and rate-determining step from the rate equation, or vice versa; qualitative effect of temperature on the rate constant; heterogeneous catalysis (iron in the Haber process; palladium, platinum, and rhodium in catalytic converters) and homogeneous catalysis (nitrogen oxides catalyzing the oxidation of sulfur dioxide in the atmosphere; Fe²⁺/Fe³⁺ catalyzing the reaction between I⁻ and S₂O₈²⁻).

3. Cambridge A Level: Inorganic Chemistry (Chapters 27–28)

• Chapter 27 Group 2: Trends in the thermal stability of nitrates and carbonates (effect of ionic radius on the polarization of large anions); changes in the solubility and enthalpy of solution of hydroxides and sulfates (explained by the relative magnitudes of enthalpy of hydration and lattice energy);
• Chapter 28 Transition Elements (Titanium to Copper): Definition of transition elements; drawing 3d_xy and 3d_z² orbitals; four properties and their explanations: variable oxidation states, catalytic activity, formation of complex ions, and colored compounds; ligands (monodentate, bidentate such as ethylenediamine and ethanedioate, multidentate such as EDTA⁴⁻); geometries of linear, square planar, tetrahedral, and octahedral complexes; coordination number; ligand exchange in copper(II) and cobalt(II) complexes; using E° to predict redox reactions; calculations involving MnO₄⁻ and C₂O₄²⁻, MnO₄⁻ and Fe²⁺, Cu²⁺ and I⁻; d-orbital splitting and the color of complexes; cis-trans and optical isomerism in complexes; stability constant Kstab.

4. Cambridge A Level: Organic Chemistry and Analysis (Chapters 29–37)

• Chapter 29 Introduction to A Level Organic Chemistry: Naming and structures of arenes, halogenoarenes, phenols, acyl chlorides, secondary and tertiary amines, amides, and amino acids; terminology for electrophilic substitution and addition-elimination mechanisms; shape of benzene, sp² hybridization, and delocalized π system; optical isomerism, and the significance of chirality in pharmaceutical synthesis (resolution of racemic mixtures, chiral catalysts);
• Chapter 30 Arenes: Halogenation, nitration, Friedel-Crafts alkylation and acylation, side-chain oxidation, and hydrogenation of benzene and methylbenzene; electrophilic substitution mechanism; whether halogenation occurs on the side chain or the benzene ring; directing effects of substituents (limited to –NH₂, –OH, –R, –NO₂, –COOH, –COR);
• Chapters 31–33: Comparing the reactivity of halogenoalkanes and halogenoarenes; preparation, reactions, and acidity of phenol, and comparing the acidity of water, phenol, and ethanol; comparing the acidity of carboxylic acids, phenol, and alcohols, and the acidity of chloro-substituted carboxylic acids; further oxidation of methanoic acid and ethanedioic acid; preparation, five reactions, and addition-elimination mechanism of acyl chlorides, and comparing the ease of hydrolysis of acyl chlorides, halogenoalkanes, and halogenoarenes;
• Chapter 34 Nitrogen Compounds: Preparation and basicity of amines; preparation of phenylamine, diazonium salts and azo dyes; comparing the basicity of ammonia, ethylamine, and phenylamine; preparation, hydrolysis, and reduction of amides, and why amides are much less basic than amines; zwitterions and isoelectric point of amino acids, peptide bonds, and interpreting electrophoresis results;
• Chapter 35 Polymerization: Condensation polymerization of polyesters and polyamides; deducing the repeating unit from the monomer, or vice versa; identifying the type of polymerization; polyolefins are hard to degrade, some polymers are photodegradable, and polyesters and polyamides are hydrolyzable;
• Chapter 36 Organic Synthesis: Identifying functional groups in multifunctional molecules and predicting their properties; designing multi-step synthetic routes; analyzing reaction types, reagents, and by-products in synthetic routes;
• Chapter 37 Analytical Techniques: Thin-layer chromatography (Rf values); gas-liquid chromatography (retention time, percentage composition of mixtures); carbon-13 NMR; proton NMR (chemical shift, peak area, n + 1 splitting rule, TMS standard, deuterated solvents, using D₂O to identify O–H and N–H protons).

5. Edexcel Unit 4: Rates, Equilibria, and Further Organic Chemistry

• Kinetics II: Rate equations, order (0, 1, 2), half-life, rate-determining step, and mechanism; using the rate equation for the hydrolysis of halogenoalkanes as evidence for S_N1 and S_N2 mechanisms; calculating and graphing to find activation energy (Arrhenius equation provided if needed); heterogeneous catalysis;
• Entropy and Energetics: Entropy as a measure of the disorder of a system; ΔS_total = ΔS_system + ΔS_surroundings, ΔS_surroundings = −ΔH/T, using ΔS_total to predict feasibility and calculate feasible temperatures (the syllabus notes ΔG can be used, but it is not required); thermodynamic and kinetic stability; Born-Haber cycles; comparing experimental and theoretical lattice energy values and the partial covalent character of ionic bonds; enthalpy of solution, enthalpy of hydration;
• Chemical Equilibria: Expressions and calculations for Kc and Kp (partial pressures in atm); effects of temperature, pressure, and catalysts on the equilibrium constant and equilibrium position;
• Acid-Base Equilibria: Brønsted-Lowry acids and bases; calculating pH, Ka, pKa, and Kw; determining Ka from experimental data; titration curves and indicator selection; calculation and preparation of buffer solutions, and their role in biological systems;
• Organic Chemistry: Chirality and optical activity (using optical rotation data as evidence for S_N1 and S_N2 mechanisms); naming and reactions of aldehydes and ketones; reactions of carboxylic acids, acyl chlorides, and esters; polyesters;
• Spectroscopy and Chromatography: Deducing structures using exact molecular mass from mass spectrometry; carbon-13 and proton NMR (including high-resolution); Rf values in paper and thin-layer chromatography; coupling high-performance liquid chromatography and gas chromatography with mass spectrometry (e.g., in forensics and doping control).

Core practicals: Titration method for the rate of reaction between iodine and propanone and the "iodine clock" reaction (9a, 9b), measuring activation energy (10), measuring the Ka of a weak acid (11).

6. Edexcel Unit 5: Transition Metals and Organic Nitrogen Chemistry

• Redox Equilibria: Standard electrode potentials and the standard hydrogen electrode; cell EMF and cell diagrams; E°cell is proportional to total entropy change and ln K; limitations of predictions using E°; redox titration calculations and measurement uncertainty; Fuel cells (electrode reactions in hydrogen-oxygen fuel cells in acidic and alkaline electrolytes);
• Transition Metals: Definition and electron configurations; variable oxidation states; ligands and coordinate bonds; origin of color and reasons why some ions are colorless; octahedral, tetrahedral, and square planar complexes; bidentate and hexadentate ligands; ligand substitution of CO for O₂ in hemoglobin; colors and interconversions of the four oxidation states of vanadium; conversion between dichromate and chromate ions; amphoteric behavior; explaining the stability of multidentate ligand substitution using ΔSsystem; heterogeneous catalysis such as V₂O₅ and catalytic converters, homogeneous catalysis of Fe²⁺, and autocatalysis of Mn²⁺;
• Arenes: Thermochemical, X-ray diffraction, and infrared data as evidence for the delocalized structure of benzene; electrophilic substitution reactions and mechanisms of benzene; reaction of phenol with bromine water;
• Organic Nitrogen Compounds: Nomenclature of amines, amides, and amino acids; reactions and basicity of amines; preparation and diazotization of aromatic amines; amides; condensation polymers and their properties (including the water solubility of polyvinyl alcohol); acidity and basicity of amino acids, zwitterions, optical activity, and peptide bonds;
• Organic Synthesis: Deducing structures from combustion analysis, elemental percentages, functional group reactions, infrared, mass spectrometry, and NMR data; Grignard reagents for carbon chain extension; designing synthesis routes of no more than four steps; selecting experimental procedures and identifying hazards; refluxing, washing, extraction, recrystallization, drying, distillation, steam distillation, and measuring melting and boiling points.

Core practicals: electrochemical cells (12), two redox titrations (13a, 13b), preparation of a transition metal complex (14), analysis of inorganic and organic unknowns (15), preparation of aspirin (16).

VII. Comparison Between the Two Exam Boards (Excerpt)

The practical implication is: when using textbooks or exercises from the other exam board, you must select content according to your own syllabus. For example, Cambridge students need to specifically practice the Nernst equation, solubility product, and Kstab; Edexcel students need to be proficient in using ΔStotal to determine feasibility and master fuel cells and Grignard reagents.

VIII. How to Study

Here are some empirical suggestions:

1. Clarify the concept chain in physical chemistry first: Energetics (lattice energy, enthalpy of solution, entropy, feasibility) and electrochemistry (electrode potentials, feasibility, relationship with equilibria) are interconnected; deduce them step by step in the order of the syllabus;
2. Organize calculations into a checklist of question types: Born-Haber cycles, entropy and feasibility temperature, pH and buffer solutions, rate constants and half-lives, redox titrations; write a complete example question for each type (see Article 197 for the format);
3. Organize transition metals by "color—ligand—reaction": Make a comparison table of the complex colors, ligand substitution reactions, and observations for each ion;
4. Expand the organic chemistry conversion map: Add arenes, phenol, acyl chlorides, amines, amides, amino acids, and polymers to the AS map, labeling the reagents, conditions, and mechanisms;
5. Practice NMR spectra extensively: First count the environments, then look at the peak areas, and finally look at the splitting to deduce the structure step by step;
6. Do not neglect Year 1 content: Year 2 papers from both exam boards may test knowledge from Year 1.

Conclusion

A-Level Chemistry has no optional topics; physical chemistry, inorganic chemistry, organic chemistry, and analytical chemistry in Year 2 are all compulsory. The two exam boards are broadly similar, but there are differences in how entropy change is handled, the year in which Kp and carbonyl compounds are taught, and whether topics like the Nernst equation, solubility product, fuel cells, and Grignard reagents are included. Go through each chapter according to your own syllabus, and combine this with core practicals and past paper practice to create a checklist for your Year 2 revision. If you need A-Level Chemistry tutoring, feel free to chat with our teachers.

Verification note: This article was verified in September 2026: the content and notes for each subsection of Cambridge 9701 Chapters 23–37 (including ΔSsurroundings not required and Kb not tested), as well as Kp and carbonyl compounds belonging to the AS section, are from the Cambridge International "Chemistry 9701 syllabus for 2025, 2026 and 2027"; the duration, marks, and weightings of Papers 4 and 5 were verified in Article 166 on this site. The duration, marks, weightings, exam sessions, paper structure, data booklet, minimum math marks requirement, synoptic question notes, topic content, and core practicals 9–16 for Edexcel Units 4 and 5 are from the Pearson IAL Chemistry Specification (Edition 1, September 2017). "Not in the syllabus" in the comparison table means we did not find the corresponding entry in the syllabus content list. The content is our excerpted translation. The study methods are our empirical suggestions.

References:

• Cambridge International：Chemistry 9701 Syllabus 2025–2027（PDF）
• Pearson Edexcel：International A Level Chemistry Specification（PDF）