A Level Chemistry Topics by Exam Board: Full List

In this article, you’ll find a roadmap of all the A Level chemistry topics you'll encounter in your revision for the major exam boards: AQA, Edexcel and OCR (A).

AQA A Level Chemistry (7405) Topics

AQA A Level Chemistry is split into 3 main topics; Physical Chemistry, Inorganic Chemistry and Organic Chemistry. These topics are then divided into a number of sections. 

The AQA A Level Chemistry course also contains a number of Required Practicals that are linked to specific topics.

Topic 3.1 Physical Chemistry

1. Section 3.1.1 Atomic Structure

Understanding atomic structure is key to explaining chemical properties and periodic trends. This topic examines the basic particles: protons, neutrons, and electrons. Their properties play a key role in determining reactivity. You will learn how mass spectrometry determines isotopic composition and relative atomic mass.

The electron configuration of atoms shows us details about chemical bonding, periodicity, and ionisation energies. Studying the ionisation energies reveals quantum shells and subshells, which helps to predict how elements react.

Finally, you will examine energy levels (1s, 2s, 2p, etc.) as a structured model for electron arrangement. This model reinforces our understanding of periodic trends and the behaviour of elements.

Key concepts include:

• Fundamental particles (protons, neutrons, electrons)

• Mass number, isotopes & relative atomic mass (Aᵣ)

• Mass spectrometry (ionisation, acceleration, detection)

• Electron configuration (s-, p-, d-, f- orbitals) & energy levels

• Successive ionisation energy & evidence for shells and subshells

• Trends in ionisation energies & periodicity

Exam Tip: Look for large jumps in successive ionisation energies—these indicate a new electron shell has been reached.

2. Section 3.1.2 Amount of substance

Understanding how much of a substance is involved in a reaction is key in chemistry. This topic covers the mole concept and its links to particles, mass, and volume. You will learn to perform stoichiometric calculations, balance equations, and use the ideal gas equation to find gas volumes.

You will also explore the importance of concentration in solutions. Titration techniques will help determine unknown concentrations. Additionally, you will study percentage yield and atom economy. Both are important for assessing reaction efficiency and sustainability.

Key concepts include:

• The mole & Avogadro constant

• Empirical & molecular formulae

• Balanced equations & reacting masses

• Ideal gas equation (pV = nRT)

• Solution concentrations & titrations

• Percentage yield & atom economy

This topic includes 1 required practical:

• Required Practical 1: Make up a volumetric solution and carry out a simple acid–base titration.

Exam Tip: Always check that your units match in calculations—volume should be in dm³ for gas laws and concentration formulas.

3. Section 3.1.3 Bonding

Atoms bond in different ways, which affects their structure, reactivity, and physical properties. This topic looks at ionic, covalent, and metallic bonding. It also explains how electron pair repulsion theory shapes molecules.

You will learn about electronegativity and polarity. This helps you understand why some molecules have dipoles while others do not. The role of intermolecular forces on boiling points, solubility, and material strength is also discussed.

You will also explore dative covalent bonding. In this case, both electrons in a bond come from the same atom. This concept is key for ammonium ions (NH₄⁺) and transition metal complexes.

Key concepts include:

• Ionic, covalent & metallic bonding

• Dative covalent bonding & examples

• Molecular shape & bond angles (VSEPR theory)

• Electronegativity & bond polarity

• Intermolecular forces (London forces, dipole interactions, hydrogen bonding)

• Properties of simple & giant structures

Common Mistake: A molecule with polar bonds is not always polar as the shape can determine whether dipoles cancel out.

4. Section 3.1.4 Energetics

Every chemical reaction involves changes in energy. These changes determine if heat is released or absorbed. This topic examines enthalpy changes in reactions, formation, and combustion. It also looks at measuring these changes with calorimetry.

Hess’s Law allows for indirect calculations of these changes. Bond enthalpy calculations help estimate the energy needed for a reaction. You will also explore why mean bond enthalpies differ from actual values. This happens because bond environments can vary.

Key concepts include:

• Standard enthalpy changes (reaction, formation, combustion)

• Hess’s Law & enthalpy cycles

• Bond enthalpies & why calculated values differ from experimental values

• Calorimetry (Q = mcΔT)

This topic includes 1 required practical:

• Required Practical 2: Measurement of an enthalpy change.

Practical Application: Enthalpy calculations are crucial in fuels and energy production, helping to determine the efficiency of combustion reactions.

5. Section 3.1.5 Kinetics

Some reactions happen in just milliseconds, while others can take years. This topic looks at why reaction rates vary, focusing on collision theory and activation energy. You will explore how temperature, concentration, pressure, and catalysts change reaction speed.

Graphical methods help determine reaction rates. The Maxwell-Boltzmann distribution shows why only some particles react. You will also look at how catalysts lower activation energy by offering an alternative pathway and their role in industrial processes.

Key concepts include:

• Collision theory & activation energy

• Factors affecting rate (temperature, concentration, pressure, catalysts)

• Rate calculations & graphical methods

• Maxwell-Boltzmann distribution

• Effect of catalysts & energy profiles

This topic includes 1 required practical:

• Required Practical 3: Investigation of how the rate of a reaction changes with temperature.

Common Mistake: Increasing temperature does not raise the curve on a Maxwell-Boltzmann graph; it shifts the distribution, increasing the proportion of molecules with energy ≥ Eₐ.

6. Section 3.1.6 Chemical equilibria, Le Chatelier’s principle & K_c 

Chemical equilibrium shows how far a reaction proceeds, not how quickly it occurs. In reversible reactions, equilibrium happens when the rates of the forward and backward reactions are equal. At this point, the concentrations of reactants and products stay constant. You will learn about Le Chatelier’s Principle, which predicts how equilibrium reacts to changes in temperature, pressure, and concentration.

This topic also covers equilibrium constants (Kc and Kp). These constants help you calculate the extent of a reaction at equilibrium. You will see how Kc and Kp change with temperature. Remember, only temperature affects the value of equilibrium constants, while changes in concentration or pressure do not.

Key concepts include:

• Dynamic equilibrium & reversible reactions

• Le Chatelier’s Principle & predicting equilibrium shifts

• Equilibrium constant (K_c) & calculations

• Equilibrium constant (K_p) for gaseous reactions

• Effect of temperature on K_c & K_p

Exam Tip: A catalyst speeds up the rate of reaching equilibrium but does not change the position of equilibrium or K_c/K_p.

7. Section 3.1.7 Oxidation, reduction and redox equations

Redox reactions involve electron transfer. Oxidation means losing electrons. Reduction means gaining electrons. By assigning oxidation states, you can spot which species are oxidized and which are reduced.

This topic also covers half-equations. They help you balance redox reactions step by step. You will also study disproportionation reactions. In these, the same species is both oxidized and reduced, as seen in chlorine’s reaction with water.

Key concepts include:

• Oxidation (electron loss) & reduction (electron gain)

• Oxidising & reducing agents

• Assigning oxidation states

• Writing & combining half-equations

• Balancing full redox equations

• Disproportionation reactions (e.g., chlorine & water)

Common Mistake: When balancing redox equations, make sure electron transfer is equal on both sides as this is a frequent error identified by examiners.

8. Section 3.1.8 Thermodynamics (A-level only)

Energy changes decide if a reaction can occur. This topic builds on enthalpy changes. It introduces entropy (S), a measure of disorder, and Gibbs free energy (ΔG), which predicts if a reaction is thermodynamically feasible.

You will learn how Born-Haber cycles calculate lattice enthalpy. They explain why some ionic compounds are more stable than others.

Key concepts include:

• Enthalpy change (ΔH) & entropy change (ΔS)

• Gibbs free energy equation (ΔG = ΔH - TΔS)

• Feasibility of reactions (when ΔG ≤ 0)

• Lattice enthalpy & Born-Haber cycles

• Enthalpy of solution & hydration enthalpy

Practical Application: Entropy explains why ice melts at 0 °C. Even though the process is endothermic, the increase in disorder (ΔS) makes it spontaneous.

9. Section 3.1.9 Rate equations (A-level only)

The rate equation shows how reactant concentrations affect speed. Reaction orders reveal whether a reactant has no effect, a proportional effect, or a squared effect on rate. Analyzing experimental data lets you determine rate equations, rate constants (k), and activation energy (E_a). The Arrhenius equation links temperature to rate, explaining why reactions speed up with heat.

Key concepts include:

• Rate equation & reaction orders

• Rate constant (k) & its units

• Determining rate equations from experimental data

• Graphical methods: concentration-time & rate-concentration graphs

• Arrhenius equation (k = Ae⁻ᴱᵃ/ᴿᵀ) & activation energy

This topic includes 1 required practical:

• Required Practical 7: Measuring the rate of reaction:

  • by an initial rate method

  • by a continuous monitoring method.

Exam Tip: A reaction order must be determined experimentally because it is not the same as the stoichiometric coefficient in the balanced equation.

10. Section 3.1.10 Equilibrium constant K_p for homogeneous systems (A-level only)

Many industrial processes involve gases, where pressure affects equilibrium yield. This topic introduces K_p, the equilibrium constant for gaseous reactions. It is calculated using partial pressures. 

You will learn how to express K_p from a balanced equation, calculate equilibrium values, and understand how temperature changes affect K_p. The effect of catalysts on equilibrium position is also discussed.

Key concepts include:

• K_p as the equilibrium constant for gases

• Calculating K_p from partial pressures

• Using mole fractions to determine partial pressures

• Effect of temperature on K_p

• Catalysts and equilibrium position

Exam Tip: K_p is only affected by temperature, changes in pressure or concentration do not alter its value.

11. Section 3.1.11 Electrode potentials & electrochemical cells (A-level only) 

Electrochemical cells convert redox reactions into electrical energy. In these cells, electrons flow through an external circuit instead of moving directly between reactants.

This topic covers standard electrode potentials (E^o) and the electrochemical series. It explains how to predict reaction feasibility and shows how cells power batteries and fuel cells. You will also learn how different factors affect cell voltage.

Key concepts include:

• Redox reactions in electrochemical cells

• Standard electrode potentials (E^o) & measurement

• Electrochemical series & predicting reaction feasibility

• Constructing cell diagrams & calculating EMF

• Fuel cells & commercial applications

This topic includes 1 required practical:

• Required Practical 8: Measuring the EMF of an electrochemical cell.

Practical Application: Electrochemical cells are used in batteries and fuel cells, including those powering electric vehicles.

12. Section 3.1.12 Acids & bases (A-level only) 

Acids and bases drive many biological, industrial, and environmental processes. The pH scale measures acidity and buffer solutions help maintain pH stability. You will explore acid-base equilibria, including how to calculate pH, K_a, and pK_a for weak acids. Titration curves will also be studied to understand neutralisation reactions and indicator selection.

Key concepts include:

• Brønsted-Lowry acids and bases (proton transfer)

• The pH scale & hydrogen ion concentration

• K_a, and pK_a for weak acids

• The ionic product of water (K_w) & pH of strong bases

• Titration curves & choosing appropriate indicators

• Buffer solutions & maintaining constant pH

This topic includes 1 required practical:

• Required Practical 9: Investigate how pH changes when a weak acid reacts with a strong base and when a strong acid reacts with a weak base.

Common Mistake: K_a values are often very small, so make sure you use standard form correctly when calculating pH.

Topic 3.2 Inorganic Chemistry

1. Section 3.2.1 Periodicity 

The periodic table is more than a list of elements. It shows trends in structure, bonding, and reactivity. You will explore how atomic radius, first ionisation energy, and melting point change across Period 3.

These trends arise from nuclear charge, electron shielding, and bonding types. Understanding periodicity helps chemists predict chemical behaviour and explain changes across periods and groups.You will also study exceptions. For example, aluminium’s first ionisation energy is lower than magnesium’s, and oxygen’s is lower than nitrogen’s.

Key concepts include:

• Classification of elements (s-, p-, d-, f-blocks)

• Trends in atomic radius across Period 3

• First ionisation energy across a period & down a group

• Ionisation energy anomalies (Be→B and N→O trends)

• Melting points explained by structure & bonding

Exam Tip: Ionisation energy trends include exceptions. For example, Be → B and N → O do not follow the general pattern.

2. Section 3.2.2 Group 2, the alkaline earth metals 

Group 2 elements show predictable trends in reactivity and solubility. Moving down the group, atomic radius and reactivity increase, while ionisation energy decreases. You will study the solubility of hydroxides and sulfates and learn about their uses in medicine and industry.

The topic also explores why barium sulfate is insoluble and its role in sulfate ion tests. You will study the thermal decomposition of Group 2 carbonates, which is a key reaction in manufacturing lime and cement.

Key concepts include:

• Trends in atomic radius, ionisation energy & melting points

• Reactions of Mg–Ba with water

• Solubility of hydroxides & sulfates (Mg–Ba)

• Uses of Group 2 compounds (medicine, agriculture, flue gas desulfurisation)

• Testing for sulfate ions with BaCl₂ solution

• Thermal decomposition of Group 2 carbonates & oxides

Practical Application: Barium sulfate is used in X-rays as it is insoluble and safe to ingest, helping doctors view the digestive tract.

3. Section 3.2.3 Group 7(17), the halogens 

Halogens are reactive non-metals. They show trends in electronegativity, boiling points, and redox behaviour. Down the group, oxidising ability falls while halide ions become stronger reducing agents. Displacement reactions between halogens and halide ions demonstrate these trends.

This topic covers qualitative tests for halide ions and their reactions with concentrated sulfuric acid. You will study disproportionation reactions, where the same element is both oxidised and reduced. Examples include chlorine reacting with water and with cold and hot alkali. Finally, you will see how chlorine plays a key role in water treatment, weighing the risks and benefits of chlorination.

Key concepts include:

• Trends in electronegativity & boiling points

• Oxidising ability of halogens & displacement reactions

• Reducing ability of halide ions

• Reactions of NaCl, NaBr & NaI with concentrated H₂SO₄

• Testing for halide ions using silver nitrate & ammonia

• Disproportionation reactions (chlorine with water & alkali)

• Chlorine reactions with water & sodium hydroxide

• Uses of chlorine in water treatment & associated risks

This topic includes 1 required practical:

• Required Practical 4: Carry out simple test-tube reactions to identify:

  • cations – Group 2, NH₄⁺

  • anions – Group 7 (halide ions), OH^-, CO₃^2-, SO₄^2-

Real-World Connection: Chlorine is used in water purification to kill bacteria, but concerns about toxic by-products remain a topic of debate.

4. Section 3.2.4 Properties of Period 3 elements & their oxides (A-level only) 

Elements across Period 3 show clear trends in structure and reactivity. They react with oxygen and water in distinct ways.

The oxides of sodium, magnesium, aluminium, silicon, phosphorus, and sulfur differ in melting points, bonding, and solubility. When these oxides react with water, they form solutions with different pH levels, revealing their acidic or basic nature.

You will study how oxide bonding determines acid-base behaviour. Ionic oxides form alkaline solutions. Covalent oxides form acids. Amphoteric oxides react with both acids and bases.

Key concepts include:

• Reactions of Na and Mg with water

• Formation of oxides (Na₂O, MgO, Al₂O₃, SiO₂, P₄O₁₀, SO₂, SO₃)

• Trends in melting points of oxides

• Reactions of oxides with water & resulting pH

• Acidic, basic & amphoteric behaviour of oxides explained by bonding

Practical Application: The acidic and basic behaviour of oxides explains their use in industry—for example, aluminium oxide as a refractory material and silicon dioxide in glass production.

5. Section 3.2.5 Transition metals (A-level only) 

Transition metals have unique properties. Their partially filled d-orbitals let them form coloured compounds, variable oxidation states, and complex ions. They also act as catalysts in many industrial processes by changing oxidation states and forming reaction intermediates.

You will explore ligand substitution, coordination numbers, and stereoisomerism in complex ions. You will also learn the differences between homogeneous and heterogeneous catalysis.

Additionally, you will study autocatalysis, where the reaction product acts as a catalyst. For example, Mn²⁺ catalyses the oxidation of ethanedioate ions by acidified manganate(VII).

Key concepts include:

• Definition of a transition metal (Ti–Cu)

• Complex ion formation & ligand types

• Formation of coloured compounds

• Variable oxidation states & redox behaviour

• Catalytic properties (homogeneous & heterogeneous)

• Haber process (Fe catalyst) & Contact process (V₂O₅ catalyst)

• Autocatalysis (e.g., Mn²⁺ in ethanedioate oxidation)

• Catalyst poisoning & economic implications

Exam Tip: Catalyst poisoning reduces efficiency by blocking active sites—this is why lead poisons catalytic converters, leading to the phase-out of lead petrol.

6. Section 3.2.6 Reactions of ions in aqueous solution (A-level only)

Transition metal ions in solution undergo characteristic reactions that change colour depending on ligands, pH, and oxidation state. Test-tube reactions help identify iron, copper, and aluminium complexes based on their reaction with hydroxide, ammonia, and carbonate ions.

Key concepts include:

• Formation of metal-aqua complexes ([M(H₂O)₆]²⁺ and [M(H₂O)₆]³⁺)

• Comparison of acidity between [M(H₂O)₆]²⁺ and [M(H₂O)₆]³⁺

• Precipitation reactions with OH^-, NH₃, and CO₃^2-

• Amphoteric behaviour of Al(OH)₃

This topic includes 1 required practical:

• Required Practical 11: Carry out simple test-tube reactions to identify transition metal ions in aqueous solution.

Practical Application: These reactions are essential for qualitative analysis, allowing chemists to identify unknown metal ions in solution using simple lab techniques.

Topic 3.3 Organic Chemistry

1. Section 3.3.1 Introduction to organic chemistry

Organic chemistry studies carbon compounds. It is crucial in medicine, materials science, and industry. You will learn the IUPAC naming system to ensure clear communication.

The topic introduces functional groups and homologous series. It covers key reaction mechanisms like radical and nucleophilic substitution. You will also explore isomerism, including structural isomers and stereoisomers (E/Z).

Finally, mass spectrometry is introduced. Molecular ion peaks (M⁺) help determine molecular mass, and fragmentation patterns reveal structure.

Key concepts include:

• Nomenclature & IUPAC naming conventions

• Functional groups & homologous series

• Types of formulae (empirical, molecular, displayed, skeletal, structural)

• Reaction mechanisms (radical & nucleophilic substitution)

• Structural & stereoisomerism (E/Z & cis-trans isomerism)

• Mass spectrometry: molecular ion peaks & fragmentation patterns

Exam Tip: When naming compounds, identify the longest carbon chain first, then number it to give the lowest possible numbers to functional groups.

2. Section 3.3.2 Alkanes

Alkanes are saturated hydrocarbons with only single C–C bonds. They are unreactive, making them ideal fuels and lubricants.

You will study the fractional distillation of crude oil, which is a key process for producing fuels and petrochemicals. The topic covers both complete and incomplete combustion. It also examines the environmental impact of pollutant gases.

You will also explore cracking reactions. These reactions produce shorter, more useful hydrocarbons.

Key concepts include:

• Structure & properties of alkanes

• Fractional distillation of crude oil

• Complete vs incomplete combustion & pollutant formation

• Catalytic & thermal cracking

• Reactions of alkanes (free radical substitution)

Common Mistake: In free radical substitution, remember that propagation steps repeat multiple times before termination—this is how multiple products form.

3. Section 3.3.3 Halogenoalkanes

Halogenoalkanes contain a halogen atom (F, Cl, Br, I) bonded to a carbon atom. Their reactivity depends on bond polarity and bond enthalpy. You will explore their nucleophilic substitution reactions with hydroxide, cyanide, and ammonia. These reactions produce alcohols, nitriles, and amines. The topic also introduces elimination reactions, which form alkenes from halogenoalkanes.

Key concepts include:

• Bond polarity & reactivity of C-X bonds

• Nucleophilic substitution with OH^-, CN^-, NH₃

• Elimination reactions & alkene formation

• Uses of halogenoalkanes (solvents, refrigerants, pharmaceuticals)

Practical Application: Chlorofluorocarbons (CFCs) were once widely used in aerosols and refrigerants, but their impact on the ozone layer led to global restrictions.

4. Section 3.3.4 Alkenes

Alkenes are unsaturated hydrocarbons with at least one C=C double bond. This bond makes them more reactive than alkanes. It is a region of high electron density that attracts electrophiles.

Their addition reactions have key industrial uses. They are vital in producing polymers and alcohols. This topic covers electrophilic addition, Markovnikov’s rule, and the formation of addition polymers.

Key concepts include:

• Structure & bonding in alkenes (σ and π bonds, electron density)

• Electrophilic addition reactions with HBr, H₂SO₄, and Br₂

• Markovnikov’s rule & major/minor product formation

• Testing for unsaturation using bromine water

• Addition polymerisation & properties of polyalkenes

Practical Application: PVC (polyvinyl chloride) and poly(ethene) are widely used plastics, with properties modified by plasticisers to enhance flexibility.

5. Section 3.3.5 Alcohols

Alcohols are versatile organic compounds. They are used in fuels, solvents, and pharmaceuticals. They can be made by hydrating alkenes or through fermentation, with ethanol as a key biofuel.

Alcohols are classified as primary, secondary, or tertiary, which affects their reactivity. You will study oxidation, dehydration, and substitution reactions. You will also learn methods to distinguish between aldehydes and ketones.

Key concepts include:

• Production of alcohols (hydration of alkenes, fermentation)

• Classification: primary, secondary & tertiary alcohols

• Oxidation of alcohols using acidified potassium dichromate

• Distinguishing aldehydes & ketones (Tollens’ test & Fehling’s solution)

• Elimination reactions: dehydration to form alkenes

This topic includes 1 required practical:

• Required Practical 5: Distillation of a product from a reaction.

Exam Tip: Primary alcohols oxidise to aldehydes or carboxylic acids, depending on reaction conditions. Distillation produces aldehydes, while reflux leads to carboxylic acids.

6. Section 3.3.6 Organic analysis

Identifying organic compounds depends on qualitative tests and spectroscopic methods. This topic includes test-tube reactions to find functional groups. It also covers mass spectrometry and infrared (IR) spectroscopy for determining molecular structure. Being able to read spectra and use different techniques is key for today’s chemical analysis.

Key concepts include:

• Test-tube reactions for alcohols, aldehydes, alkenes & carboxylic acids

• Mass spectrometry: molecular ion peaks & fragmentation patterns

• Infrared spectroscopy: identifying functional groups from absorption peaks

• Fingerprint region for molecular identification

This topic includes 1 required practical:

• Required Practical 6: Tests for alcohol, aldehyde, alkene, and carboxylic acid

Common Mistake: The broad O–H peak in IR spectra helps identify alcohols and carboxylic acids, but carboxylic acids also show a strong C=O peak.

7. Section 3.3.7 Optical isomerism (A-level only)

Some molecules exist as non-superimposable mirror images. This is called optical isomerism. It happens when a molecule has a chiral centre, usually a carbon bonded to four different groups. The enantiomers rotate plane-polarised light in opposite directions but share identical properties in achiral environments. You will also study racemic mixtures, which contain equal amounts of both enantiomers and are optically inactive.

Key concepts include:

• Chirality & asymmetric carbon atoms

• Enantiomers & their effect on plane-polarised light

• Racemic mixtures & optical inactivity

• Drawing 3D representations of optical isomers

Exam Tip: In nucleophilic addition of HCN to aldehydes and unsymmetrical ketones, a racemic mixture forms because the nucleophile can attack from either side of the planar carbonyl group.

8. Section 3.3.8 Aldehydes & ketones (A-level only)

Aldehydes and ketones are carbonyl compounds. They have a C=O group. Aldehydes oxidize to form carboxylic acids, but ketones resist oxidation.

You will explore reduction reactions using NaBH₄. You will also learn about nucleophilic addition with HCN, which extends the carbon chain. Qualitative tests like Tollens’ reagent and Fehling’s solution help distinguish aldehydes and ketones.

Key concepts include:

• Structure & properties of aldehydes & ketones

• Oxidation of aldehydes to carboxylic acids

• Reduction of carbonyls to alcohols using NaBH₄

• Nucleophilic addition with HCN to form hydroxynitriles

• Distinguishing aldehydes & ketones (Tollens’ & Fehling’s tests)

Common Mistake: Tollens’ reagent gives a silver mirror with aldehydes, but ketones do not react. Make sure you know the tests and results as examiners often comment about mixing them up.

9. Section 3.3.9 Carboxylic acids & derivatives (A-level only)

Carboxylic acids are weak acids. They react with metals, carbonates, and bases to form salts, water, and CO2. They also undergo esterification with alcohols to form esters. Esters are used in solvents, perfumes, and food flavourings. 

The topic also explores acyl chlorides, which are highly reactive derivatives of carboxylic acids. Acyl chlorides undergo nucleophilic addition-elimination with water, alcohols, ammonia, and amines. The products of these reactions are carboxylic acids, esters, and amides.

Key concepts include:

• Acidity & reactions of carboxylic acids

• Esterification reactions & ester hydrolysis

• Acyl chlorides & nucleophilic addition-elimination

• Formation of amides from acyl chlorides

• Uses of esters in industry (biodiesel, solvents, flavourings)

This topic includes 1 required practical:

• Required Practical 10: Preparation of:

  • a pure organic solid and test of its purity

  • a pure organic liquid

Practical Application: Biodiesel is produced from vegetable oils by transesterification, where triglycerides react with methanol to form methyl esters.

10. Section 3.3.10 Aromatic chemistry (A-level only)

Aromatic compounds like benzene have a unique structure. Electrons spread over a ring of carbon atoms. This delocalisation makes benzene stable and less reactive than alkenes. You will study evidence for this delocalisation model. Thermochemical data allows you to compare benzene with cyclohexa-1,3,5-triene.

The topic also covers electrophilic substitution reactions, including nitration and acylation (Friedel-Crafts reactions). These reactions are key in organic synthesis. Additionally, you will learn how nitrobenzene is formed using concentrated HNO₃ and H₂SO₄. This is essential for making aromatic amines and explosives like TNT.

Key concepts include:

• Structure & bonding in benzene (delocalisation vs Kekulé model)

• Thermochemical evidence for benzene’s stability

• Electrophilic substitution reactions (nitration & Friedel-Crafts acylation)

• Formation of nitrobenzene & its applications

• Role of catalysts (AlCl₃) in acylation reactions

• Uses of aromatic compounds in industry (explosives, pharmaceuticals, dyes)

Exam Tip: Benzene does not react with bromine water, unlike alkenes—this is evidence for its delocalised structure.

11. Section 3.3.11 Amines (A-level only)

Amines are derivatives of ammonia (NH₃). In these compounds, hydrogen atoms are replaced by alkyl or aryl groups. Their properties depend on the availability of the nitrogen lone pair. This lone pair influences their basicity and nucleophilic behaviour. You will explore how amines are prepared, their role in organic synthesis, and their use in making dyes and surfactants.

Key concepts include:

• Structure & classification of amines (primary, secondary, tertiary, quaternary)

• Preparation of aliphatic & aromatic amines

• Amines as weak bases (effect of alkyl & aryl groups on basicity)

• Nucleophilic substitution reactions with halogenoalkanes

• Formation of amides & quaternary ammonium salts

Common Mistake: Aromatic amines are weaker bases than aliphatic amines because the nitrogen lone pair is delocalised into the benzene ring, reducing its availability.

12. Section 3.3.12 Polymers (A-level only)

Polymers are long-chain molecules created by linking monomers. You will learn about addition polymers, which come from alkenes, and condensation polymers, which release a small molecule, such as water. The environmental impact of polymers and their biodegradability will also be discussed.

Key concepts include:

• Addition polymers (e.g., polyethene, polypropene)

• Condensation polymers (polyesters & polyamides, e.g., nylon, Kevlar)

• Biodegradability & hydrolysis of polyesters & polyamides

• Recycling & environmental impact of plastics

Real-World Connection: Biodegradable polyesters are being developed to reduce plastic pollution and replace non-degradable polyalkenes.

13. Section 3.3.13 Amino acids, proteins & DNA (A-level only)

Amino acids are the building blocks of proteins. They have an amine (-NH₂) and a carboxyl (-COOH) group. You will study how they react and form peptide bonds. You will also explore how DNA stores genetic information via hydrogen bonds between base pairs.

Key concepts include:

• Structure & reactions of α-amino acids

• Zwitterions & isoelectric points

• Formation of peptides & hydrolysis of proteins

• Structure of DNA & base pairing

• Role of hydrogen bonding in DNA stability

Practical Application: The base pairing in DNA (A-T, C-G) is essential for genetic inheritance and protein synthesis.

14. Section 3.3.14 Organic synthesis (A-level only)

Building complex molecules from simpler ones is the heart of organic chemistry. Chemists design multi-step routes to do this. They carefully choose reagents and conditions to transform functional groups.

You will learn purification techniques including solvent extraction, drying agents, and recrystallisation to obtain pure solids. Thin-layer chromatography (TLC) helps monitor reaction progress and check purity.

Key concepts include:

• Multi-step organic synthesis pathways

• Functional group interconversions

• Reagents & conditions for organic reactions

• Purification techniques (solvent extraction, drying agents, recrystallisation)

• Chromatography for reaction monitoring & purity assessment

• Importance of atom economy & sustainability in synthesis

Exam Tip: When planning a synthetic route, check that each step is feasible, maximises yield, and avoids unnecessary side reactions.

15. Section 3.3.15 Nuclear magnetic resonance spectroscopy (A-level only)

Understanding molecular structures is key in chemistry. NMR spectroscopy is a powerful tool for this. It shows how atomic nuclei interact with magnetic fields. This interaction reveals the arrangement of atoms in a molecule.

You will study ¹H NMR and ¹³C NMR. The n+1 rule predicts 1H NMR splitting patterns. Integration values reveal the number of protons. Chemical shifts indicate the environment of atoms. Deuterated solvents, such as CDCl₃, prevent interfering proton signals.

Key concepts include:

• ¹H NMR spectroscopy (chemical shifts, peak splitting, integration)

• ¹³C NMR spectroscopy (number and position of carbon atoms)

• The use of tetramethylsilane (TMS) as a reference

• Deuterated solvents (e.g., CDCl₃) and their role

• Interpreting spectra to identify molecular structures

Exam Tip: When analyzing ¹H NMR spectra, check the splitting pattern (n+1 rule) to determine how many hydrogen atoms are adjacent to a given proton.

16. Section 3.3.16 Chromatography (A-level only)

Chromatography is a key separation technique used in research, industry, and forensics. It separates and identifies components in a mixture based on their movement through a stationary phase. This topic covers thin-layer chromatography (TLC), gas chromatography (GC), and column chromatography (CC).

Key concepts include:

• Thin-layer chromatography (TLC) (R_f values, identifying compounds)

• Column chromatography (CC) (solid-packed column for separation)

• Gas chromatography (GC) (volatility-based separation, detection by mass spectrometry)

• Factors affecting separation (solubility, retention time, polarity)

• Applications in forensic science, pharmaceuticals, and food analysis

This topic includes 1 required practical:

• Required Practical 12: Separation of species by thin-layer chromatography.

Practical Application: Gas chromatography is widely used in drug testing and detecting banned substances in competitive sports.

What is Covered in AQA A Level Chemistry (7405) Exam Papers?

There are 3 exam papers for the AQA A Level Chemistry exam (7405) course:

Revision Resources for AQA A Level Chemistry (7405)

To help you prepare for your AQA A Level Chemistry (7405) exams, Save My Exams provides a range of high-quality revision resources:

• Revision Notes: Concise, syllabus-aligned summaries breaking down complex topics into easy-to-understand explanations. These notes are ideal for reinforcing key concepts. Try our AQA A Level Chemistry Revision notes.

• Exam-Style Topic Questions: A collection of past paper and exam-style questions organised by topic, with detailed, step-by-step solutions from expert teachers. Try our AQA A Level Chemistry Exam Questions.

• Past Papers: AQA A Level Chemistry (7405) past papers that simulate real exam conditions, helping you refine your problem-solving skills and boost confidence.Try our AQA A Level Chemistry Past papers  . 

You can access all these resources at Save My Exams - AQA A Level Chemistry (7405)

Edexcel A Level Chemistry (9CH0) Topics

Edexcel A Level Chemistry is split into 19 topics, as outlined below.

The Edexcel A Level Chemistry course also contains a number of Core Practicals that are linked to specific topics. 

1. Atomic Structure & the Periodic Table

The structure of an atom defines its chemical properties and trends in the periodic table. This topic looks at how protons, neutrons, and electrons are arranged, affecting reactivity and periodicity. You will study mass spectrometry, which includes ionisation, acceleration, deflection, and detection. This process helps determine atomic mass and isotopes. 

Electron configurations show evidence of quantum shells. Successive ionisation energies help you understand the electronic structure of elements. You will also learn how elements fit into s-, p-, and d-blocks. Finally, you will explore how periodic trends influence atomic radius, ionisation energy, and melting/boiling points.

Key concepts include:

• Subatomic particles

• Relative atomic mass (A_r) & isotopes (including mass spectrometry process)

• Electron configurations & quantum shells

• Ionisation energy trends & interpretation of ionisation energy graphs

• Classification of elements

• Periodicity

Exam Tip: Be ready to explain successive ionisation energy graphs to determine electron configurations and group placement.

2. Bonding & Structure

Bonding shapes a substance's physical and chemical properties. This topic covers ionic, covalent, and metallic bonding. It looks at how electrostatic forces, electron sharing, and delocalised electrons affect melting points, solubility, and conductivity. You will learn about molecular shape and bond angles through electron pair repulsion theory. Electronegativity and bond polarity will help you see if molecules have permanent dipoles. 

Then, you will examine intermolecular forces like London forces, dipole interactions, and hydrogen bonding. These forces explain trends in boiling points and solubility. You will also look at factors that affect metallic bond strength, including ionic charge, electron density, and lattice structure. 

Finally, you’ll study the structures of giant ionic lattices, giant covalent structures (like diamond, graphite, and silicon dioxide), and metallic bonding. This will help you understand their unique material properties.

Key concepts include:

• Ionic, covalent, and metallic bonding (including charge density effects)

• Molecular shape & bond angles

• Electronegativity & polarity

• Intermolecular forces

• Solubility trends

• Giant structures vs simple molecules

Common Mistake: Don’t confuse ionic lattice energy with metallic bonding strength. Ionic compounds rely on electrostatic forces between ions, whereas metallic bonds depend on charge density and delocalised electrons.

3. Redox I

Redox reactions are essential to chemical reactions. They involve the transfer of electrons and oxidation number changes. This topic covers oxidation and reduction, both as electron transfer and in terms of oxidation states.

You will learn how to assign oxidation numbers, classify redox and disproportionation reactions, and construct ionic half-equations. Understanding oxidising and reducing agents explains why metals form cations and non-metals form anions in redox reactions.

Key concepts include:

• Oxidation number

• Redox reactions

• Oxidising & reducing agents

• Disproportionation reactions

• Ionic half-equations

Exam Tip: Be able to identify oxidation and reduction using both electron transfer and oxidation number changes, as exam questions often require both interpretations.

4. Inorganic Chemistry & the Periodic Table

The periodic table predicts element properties and chemical behaviour. This topic examines reactivity trends and chemical properties of Groups 1, 2, and 7. This includes their reactions with water, oxygen, and acids. 

You will study solubility trends and the thermal stability of carbonates and nitrates. You will learn how displacement reactions demonstrate halogen reactivity. You will also learn qualitative analysis techniques. These include flame tests and ion precipitation reactions to help identify unknown substances.

Key concepts include:

• Group 1: Alkali metals

• Group 2: Alkaline earth metals

• Group 7: Halogens

• Flame tests

• Qualitative analysis

Practical Application: Flame tests and precipitation reactions are widely used in forensic science and environmental monitoring to identify metal and non-metal ions.

5. Formulae, Equations & Amounts of Substance

Quantitative chemistry is essential for accurate measurements and calculations. This topic includes moles, molar mass, and the Avogadro constant. These concepts are the foundation for stoichiometry and balanced equations.

You will learn to determine empirical and molecular formulae. You will also calculate reacting masses and gas volumes. The ideal gas equation (pV = nRT) will be covered, along with its assumptions.

The topic explores limiting reagents and excess reactants, which impact reaction yield. You will study solution concentrations in titrations. Finally, you will learn to evaluate measurement uncertainty and error propagation.

Key concepts include:

• The mole & Avogadro constant

• Empirical & molecular formulae

• Balanced equations & state symbols

• Reacting masses, volumes & limiting reagents

• Gas laws (pV = nRT) & ideal gas assumptions

• Solution concentrations & titrations

Exam Tip: In limiting reagent problems, always identify which reactant runs out first—this determines the maximum product yield.

6. Organic Chemistry I

Organic chemistry studies compounds made of carbon. These compounds are key to fuels, plastics, pharmaceuticals, and biological molecules. You will learn about alkanes, alkenes, and halogenoalkanes, including their structure, properties, and reactivity.

This topic covers the radical substitution and electrophilic addition mechanisms. You will also look at stereoisomerism and polymerisation. These principles are important for understanding hydrocarbon reactions and their uses in industry.

Key concepts include:

• Functional groups & homologous series

• IUPAC nomenclature

• Alkanes & combustion

• Alkenes & electrophilic addition

• Halogenoalkanes & nucleophilic substitution

• Isomerism (structural & stereoisomerism)

This topic includes 3 core practicals:

• Core Practical 4: Investigation of the rates of hydrolysis of some halogenoalkanes

• Core Practical 5: The oxidation of ethanol

• Core Practical 6: Chlorination of 2-methylpropan-2-ol using concentrated hydrochloric acid

Exam Tip: Learn how to name organic compounds systematically as small errors in IUPAC nomenclature can lead to incorrect structures or isomers.

7. Modern Analytical Techniques I

Accurate structural determination is crucial in organic chemistry, industry, and forensic science. This topic introduces mass spectrometry (MS) and infrared (IR) spectroscopy. These techniques help to identify molecular structures and functional groups in unknown compounds. 

You will learn to interpret mass spectra, identify molecular ion peaks, and analyse fragmentation patterns. In IR spectroscopy, you will recognise characteristic absorption peaks for key functional groups.

Key concepts include:

• Mass spectrometry (MS)

• Molecular ion peak (M⁺) & fragmentation

• Infrared (IR) spectroscopy

• Key IR absorptions (C–H, C=C, O–H, C=O)

This topic includes 1 core practical:

• Core Practical 7: Analysis of some inorganic and organic unknowns

Exam Tip: Always check whether an IR spectrum shows a broad O–H peak, as this helps distinguish between alcohols and carboxylic acids..

8. Energetics I

Chemical reactions involve energy changes. This topic explores how these changes are measured and calculated. You will study enthalpy changes in formation, combustion, and neutralisation reactions. Then learn how to determine enthalpy values using experimental data, Hess’s Law, and bond enthalpies. The importance of calorimetry in measuring energy transfer is also covered.

Key concepts include:

• Standard conditions (100 kPa, 298 K)

• Enthalpy change (ΔH) & enthalpy level diagrams

• Standard enthalpy changes (formation, combustion, neutralisation)

• Calorimetry & Q = mcΔT calculations

• Hess’s Law & enthalpy cycles

• Bond enthalpies & mean bond enthalpies

This topic includes 1 core practical:

• Core Practical 8: To determine the enthalpy change of a reaction using Hess’s Law

Exam Tip: Always include signs and units in enthalpy calculations—forgetting a negative sign for exothermic reactions is a common mistake.

9. Kinetics I

Reaction rates depend on particle collisions and energy. This topic explores how temperature, concentration, pressure, and catalysts affect reaction rates. You will learn how to calculate reaction rates from experimental data and graphs. The Maxwell-Boltzmann distribution allows you to explain how temperature and catalysts influence reaction rates. 

You will also explore reaction profile diagrams. This will include how catalysts lower activation energy by providing an alternative reaction pathway.

Key concepts include:

• Collision theory & activation energy

• Effect of temperature, concentration, & pressure

• Rate calculations (graphs, tangents, gradients)

• Maxwell-Boltzmann distribution & activation energy explanation

• Reaction profile diagrams

• Catalysts & alternative reaction pathways

Common Mistake: Many students misinterpret the Maxwell-Boltzmann distribution. Raising temperature does not shift the curve upward, it spreads it out, increasing high-energy collisions.

10. Equilibrium I

Reversible reactions reach dynamic equilibrium. This is where the forward and backward reactions occur at the same rate. At this point, the concentrations of reactants and products remain constant.

This topic introduces Le Chatelier’s Principle. This allows you to predict how temperature, pressure, and concentration affect equilibrium position. You will also study the equilibrium constant (K_c) and how it determines the extent of a reaction.

Key concepts include:

• Dynamic equilibrium

• Le Chatelier’s Principle

• Industrial compromises (yield vs rate)

• Equilibrium constant (K_c) & calculations

Exam Tip: Be prepared to explain why K_c depends on temperature but not on concentration or pressure.

11. Equilibrium II

This topic builds on Equilibrium I by introducing the equilibrium constant for gaseous reactions, Kp. You will explore how temperature affects both Kc and Kp. You will also learn why pressure and concentration do not alter equilibrium constants. Equilibrium data helps determine reaction feasibility.

The topic covers heterogeneous equilibria, explaining how systems with multiple phases (solid, liquid, gas) differ from homogeneous systems.

Key concepts include:

• Equilibrium constant (K_p) for gaseous systems

• Partial pressures & equilibrium calculations

• Temperature dependence of K_c & K_p

• Heterogeneous vs homogeneous equilibria

• Relationship between ΔG and K (thermodynamic feasibility)

Practical Application: Gas-phase equilibria, such as the Haber process, rely on equilibrium data to optimise ammonia yield.

12. Acid-base Equilibria

Acid-base equilibria play a key role in chemistry, medicine, and industry. This topic introduces the Brønsted-Lowry theory, defining acids as proton donors and bases as proton acceptors.

You will learn to calculate pH, determine K_a values, and understand how buffers resist pH changes. The topic also covers the Henderson-Hasselbalch equation for predicting buffer pH and the ionic product of water (K_w), which affects pH calculations for strong and weak acids.

Key concepts include:

• Brønsted-Lowry acids & bases

• Acid dissociation constant (K_a) & pK_a

• pH calculations (strong vs weak acids)

• The ionic product of water (K_w)

• Titration curves & indicators

• Buffer solutions & Henderson-Hasselbalch equation

This topic includes 1 core practical:

• Core Practical 9 – Finding the K_a value for a weak acid.

Exam Tip: When calculating K_a from pH, always check for assumptions, such as [HA] ≈ [HA]_initial, to simplify calculations.

13. Energetics II

Reaction feasibility depends on more than just enthalpy changes. This topic explores entropy (ΔS) as a measure of disorder and how it, along with enthalpy (ΔH) and temperature (T), determines if a reaction can occur.

Using the Gibbs free energy equation (ΔG = ΔH - TΔS), you will learn to predict whether a reaction is thermodynamically spontaneous under different conditions.

The topic also covers lattice energy and Born-Haber cycles. These explain why some ionic compounds are highly stable while others dissolve due to hydration enthalpy. Finally, you will consider why some thermodynamically feasible reactions do not occur due to high activation energy or kinetic barriers.

Key concepts include:

• Lattice energy & Born-Haber cycles

• ΔH_solution & ΔH_hydration

• Entropy (ΔS) & total entropy change (ΔS_total)

• Gibbs free energy (ΔG = ΔH - TΔS) & feasibility

• Relationship between ΔG and equilibrium constant (K)

• Limitations of ΔG predictions (kinetic inhibition)

Exam Tip: When using ΔG = ΔH - TΔS, make sure ΔS is in J K^-1 mol^-1, and always convert it to kJ K^-1 mol^-1 by dividing by 1000 before calculating.

14. Redox II

Redox chemistry is key to electrochemical cells, electrode potentials, and redox titrations. This topic explores how electron transfer generates electrical energy and how E° values predict reaction feasibility.

You will study the principles behind fuel cells and storage cells. Redox titrations, used in volumetric analysis to determine unknown concentrations, are also covered. Finally, the Nernst equation is introduced to explain how concentration changes affect electrode potential.

Key concepts include:

• Oxidation and reduction (electron transfer & oxidation states)

• Standard electrode potentials (E^o) & electrochemical series

• Measuring electrode potentials & calculating E^o_cell

• Nernst equation (effect of concentration on E^o values)

• Redox titrations (manganate(VII), iodine-thiosulfate)

This topic includes 2 core practicals:

• Core Practical 10 – Investigating some electrochemical cells.

• Core Practical 11 – Redox titration.

Exam Tip: When writing cell diagrams, the more positive E^o value is placed on the right, and the half-equations must be balanced for electrons.

15. Transition Metals

Transition metals have d orbitals that are only partly filled. This allows for different oxidation states, catalytic properties, and the formation of coloured complexes.

You will look into ligand exchange reactions and stereoisomerism in complex ions. Transition metals also serve as catalysts in both industrial and biological systems. The topic also includes redox behaviour and explains their role in biological molecules, industrial reactions, and materials science.

Key concepts include:

• Electronic structure of transition metals

• Variable oxidation states

• Formation of coloured ions

• Complex ions & ligand exchange

• Stereoisomerism in complexes (cis-trans & optical isomerism)

• Redox chemistry of transition metals

• Catalytic behaviour (homogeneous & heterogeneous catalysts)

This topic includes 1 core practical:

• Core Practical 12 – The preparation of a transition metal complex​

Common Mistake: Not all transition metal ions are coloured as this depends on d-orbital splitting and whether an electron transition is possible.

16. Kinetics II

Reactions occur at different speeds. This topic explores how rate equations describe reaction kinetics mathematically. You will learn how to determine reaction orders, identify the rate-determining step, and predict reaction mechanisms based on experimental data. 

The Arrhenius equation will also be introduced. This can help you understand how temperature affects the rate constant (k). The Arrhenius equation can be used to calculate activation energy from graphical data.

Key concepts include:

• Rate equations & orders of reaction (0, 1, 2)

• Rate-determining step & reaction mechanisms

• Experimental determination of rate equations

• Graphical methods (rate–concentration & Arrhenius plots)

• Half-life & first-order reactions

• The Arrhenius equation (k = Ae⁻ᴱᵃ/ᴿᵀ)

This topic includes 2 core practicals:

• Core Practical 13a & 13b – Following the rate of the iodine-propanone reaction by a titrimetric method and investigating a ‘clock reaction’ (Harcourt-Essen, iodine clock).

• Core Practical 14 – Finding the activation energy of a reaction.

Common Mistake: A reaction mechanism is not the same as a balanced equation. Only species in or before the rate-determining step appear in the rate equation.

17. Organic Chemistry II

Aromatic compounds and carbonyl chemistry play a central role in synthetic organic reactions. This topic covers the structure of benzene and its delocalised π-system. This is used to explain why it undergoes electrophilic substitution rather than addition. 

You will also study phenols, carbonyl compounds (aldehydes and ketones), and carboxylic acid derivatives. Their reactivity and functional group interconversions are explored.

Key concepts include:

• Structure & bonding in benzene (delocalised π-system)

• Electrophilic substitution (nitration, halogenation, Friedel-Crafts acylation)

• Reactions of phenols

• Aldehydes & ketones (reduction, nucleophilic addition, 2,4-DNPH test)

• Carboxylic acids & derivatives (esters, acyl chlorides, amides)

• Acylation reactions (reactions of acyl chlorides with nucleophiles)

Practical Application: Aspirin is synthesised using acylation reactions, demonstrating the importance of ester and carboxylic acid chemistry in pharmaceuticals.

18. Organic Chemistry III

Organic synthesis uses multi-step pathways to produce target molecules from simpler materials. This topic covers functional group interconversions, carbon-chain extension, and purification methods. You will also learn to plan synthetic routes, use Grignard reagents, and optimise reaction conditions for maximum yield and purity.

Key concepts include:

• Synthetic routes & multi-step synthesis

• Functional group interconversions (oxidation, reduction, hydrolysis)

• Carbon-chain extension using Grignard reagents

• Reflux & distillation

• Purification techniques (recrystallisation, solvent extraction, chromatography)

• Percentage yield & atom economy

This topic includes 1 core practical:

• Core Practical 16 – The preparation of aspirin​

Exam Tip: When planning synthetic routes, check for functional group compatibility as some reactions require specific conditions to avoid unwanted side reactions.

19. Modern Analytical Techniques II

Advanced analytical techniques determine the structure of organic compounds with high precision. This topic introduces high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy. These methods provide detailed information about molecular structure and functional groups. 

You will learn how ¹³C and ¹H NMR spectra identify the number and type of carbon and hydrogen environments. Integration values and splitting patterns reveal structural details.

Key concepts include:

• High-resolution mass spectrometry (HRMS)

• Carbon-13 NMR spectroscopy (¹³C NMR)

• Proton NMR spectroscopy (¹H NMR) & chemical shifts

• Spin-spin coupling & the (n+1) rule

• Integration values & peak splitting patterns

• Combined techniques for structural determination

Exam Tip: In ¹H NMR, OH and NH protons often do not show spin-spin coupling due to rapid proton exchange in solution.

What is covered in Edexcel A Level Chemistry exam (9CH0) papers?

There are 3 exam papers for the Edexcel A Level Chemistry exam (9CH0) course:

Revision Resources for Edexcel A Level Chemistry (9CH0)

To help you prepare for your Edexcel A Level Chemistry (9CH0) exams, Save My Exams provides a range of high-quality revision resources:

• Revision Notes: Concise, syllabus-aligned summaries breaking down complex topics into easy-to-understand explanations. These notes are ideal for reinforcing key concepts. Try our Edexcel A Level Chemistry Revision notes.

• Exam-Style Topic Questions: A collection of past paper and exam-style questions organised by topic, with detailed, step-by-step solutions from expert teachers. Try our Edexcel A Level Chemistry Exam Questions.

• Past Papers: Edexcel A Level Chemistry (9CH0) past papers that simulate real exam conditions, helping you refine your problem-solving skills and boost confidence.Try our Edexcel A Level Chemistry Past papers. 

You can access all these resources at Save My Exams - Edexcel A Level Chemistry (9CH0)

OCR A Level in Chemistry A (H432) Topics

The OCR A Level in Chemistry A course is divided into 6 modules, each containing a number of topics.

The OCR A Level in Chemistry A course also contains a number of Practical Activity Groups (PAGs). Unlike AQA and Edexcel, these practicals are not linked to specific topics. Instead, they are linked to the broader modules because the PAG system is more flexible as students complete a range of activities across the course, and teachers have discretion over when and how they integrate the practicals into specific topics.

Furthermore, PAG 12: Research and Referencing is integrated throughout the course. It is not tied to a specific module but assessed across various practical tasks and investigative work.

Module 1 – Development of practical skills in chemistry

This module underpins all other modules and is assessed in written examinations and through the Practical Endorsement.

• Practical skills - assessed in a written examination

• Practical skills - assessed in the practical endorsement

These skills are embedded across the course rather than being tested separately.

Module 2 – Foundations in chemistry

This module contains 4 topics introducing the essential chemical principles required for the course.

This module includes 2 Practical Activity Groups (PAGs):

• PAG 1: Moles Determination

• PAG 2: Acid–base Titration

Atoms, compounds, molecules & equations

How atoms interact determines the structure and behavior of all substances. This topic covers how elements combine to form compounds and molecules. You will explore how isotopes affect relative atomic mass (RAM) calculations, and how chemical formulae represent substances. 

You will also learn to balance chemical equations. This is crucial for predicting reaction yields and ensuring accurate stoichiometric relationships. Balancing equations is a key skill that helps you describe and predict chemical reactions with confidence.

Key concepts include:

• Atoms and Elements

• Compounds and Molecules

• Isotopes and Relative Atomic Masses (RAM calculations)

• Chemical Formulae

• Chemical Equations

• Ionic and Covalent Compounds

🔬 Practical Application: Balancing equations is essential for reaction yield predictions in industry and underpins many quantitative chemistry calculations.

Amount of substance

Chemists measure substances using the mole, not individual atoms or molecules. This topic explores the relationships between mass, concentration, and volume. You will learn how gas laws (pV = nRT) quantify substances in different states.

You will practice empirical and molecular formula calculations to determine compound composition. Mastering percentage yield and atom economy will show how chemical processes become more efficient.

Key concepts include:

• The Mole and Avogadro’s Constant

• Moles in Solids, Liquids, and Gases

• Ideal Gas Equation (pV = nRT) 

• Empirical and molecular formula calculations

• Reacting Masses and Stoichiometry

• Percentage Yield and Atom Economy

Exam Tip: Always check unit conversions in calculations—especially volume (cm³ to dm³) and pressure (kPa to Pa).

Acid–base & redox reactions

Acids and bases are fundamental in chemistry, while redox reactions power key processes. You will explore how acids and bases behave in solution and apply the Brønsted-Lowry definitions to distinguish them. Titrations will help determine unknown concentrations.

This topic also covers oxidation numbers and redox reactions. You will learn to balance equations and predict reaction feasibility. This is essential for electrochemistry and industrial applications.

Key concepts include:

• Acids and Bases, including Bronsted-Lowry definitions

• Strong vs Weak Acids and Bases

• Titrations

• Redox Reactions

• Oxidation Numbers

• Ionic Equations, including neutralisation reactions

Exam Tip: Assign oxidation numbers to elements carefully as they help to identify redox changes.

Electrons, bonding & structure

The arrangement and bonding of atoms determine everything from the hardness of a diamond to the conductivity of metals. This topic covers electron configurations and different types of bonding (ionic, covalent, and metallic). You will explore how intermolecular forces affect properties like boiling points and solubility. 

You will also learn how to predict molecular shapes and bond angles using VSEPR theory. This will help you to understand why some molecules are linear while others adopt more complex geometries.

Key concepts include:

• Electron Configuration

• Ionic Bonding

• Covalent Bonding 

• Shapes of molecules (VSEPR theory) and bond angles

• Electronegativity and Bond Polarity

• Intermolecular Forces

• Metallic Bonding and Structure

Practical Application: Understanding intermolecular forces helps explain boiling points, solubility, and material properties..

Module 3 – Periodic table & energy

This module includes 2 Practical Activity Groups (PAGs):

• PAG 1: Moles Determination

• PAG 2: Acid–base Titration

The Periodic table & periodicity

The periodic table is a powerful tool that allows you to predict element properties based on their position. In this topic, you will explore periodic trends, such as atomic radius, electronegativity, and ionisation energy. This includes how these properties vary across periods and down groups. 

You will also examine successive ionisation energies. These explain electron configurations and why certain elements form stable oxidation states. Mastering these trends allows you to predict the reactivity and bonding behaviour of elements.

Key concepts include:

• Periodic Table Structure

• Periodic Trends Across a Period, including successive ionisation energy

• Group Trends Down a Group

Common Mistake: Confusing atomic radius and ionic radius—positive ions are smaller than their atoms, while negative ions are larger.

Group 2 & the halogens

Group 2 and Group 17 elements show distinctive reactivity patterns. They also have vital uses, including agriculture to water purification. In this topic, you will explore how Group 2 metals become more reactive as you move down the group, while halogens become less reactive. By applying these trends, you can predict how these elements will behave in different chemical environments.

Key concepts include:

• Group 2: The Alkaline Earth Metals

• Uses of Group 2 compounds

• Reactions of Group 2 with water and dilate acids

• Group 17: The Halogens

• Uses of Group 17 Compounds

• Halogen displacement reactions

Exam Tip: Group 2 oxides and hydroxides become more soluble down the group, while sulfates become less soluble.

Qualitative analysis

Identifying unknown substances is a key skill in chemistry, from forensics to medical diagnostics. This topic covers systematic tests for different anions, cations, and gases based on their characteristic reactions. By applying these techniques, you can determine the composition of unknown samples and see how chemical testing is used in real-world investigations.

Key concepts include:

• Tests for Anions including halide, sulfate and carbonate ions

• Tests for Cations

• Tests for Gases including hydrogen, oxygen and ammonia

Common Mistake: Confusing the carbonate and sulfate tests—carbonates release gas while sulfates form a precipitate.

Enthalpy changes

Every chemical reaction involves energy changes, making it either exothermic (releasing energy) or endothermic (absorbing energy). This topic covers how enthalpy changes can be measured. It also gives key enthalpy definitions and explores reaction feasibility. 

By applying Hess’s Law, you will learn how to determine enthalpy changes indirectly. This will demonstrate why energy calculations are crucial in both industry and biology.

Key concepts include:

• Types of Enthalpy Change

• Exothermic vs. Endothermic Reactions

• Bond enthalpy calculations 

• Hess’s Law

• Born-Haber cycle for ionic compounds

Exam Tip: Use enthalpy cycle diagrams when applying Hess’s Law.

Reaction rates & equilibrium (qualitative)

Why do some reactions happen instantly while others take years? What happens when a reaction reaches equilibrium? This topic explores collision theory and how temperature, pressure, and catalysts affect reaction rates. 

You will also learn how to use the Maxwell-Boltzmann distribution graph to explain why temperature affects reaction speeds. Dynamic equilibrium and Le Chatelier’s Principle will help you predict how systems respond to changing conditions. This is an essential skill in optimising industrial processes and environmental chemistry.

Key concepts include:

• Collision Theory

• Maxwell-Boltzmann distribution graph

• Factors Affecting Rate

• Equilibrium

• Le Chatelier’s Principle

Exam Tip: Catalysts increase rate but do not affect equilibrium position.

Module 4 – Core organic chemistry

This module includes 2 Practical Activity Groups (PAGs):

• PAG 5: Synthesis of an Organic Liquid

• PAG 6: Organic Solid Preparation and Purification

Basic concepts

Organic chemistry underpins everything from biological molecules to synthetic materials. In this topic, you will learn how to name organic compounds using IUPAC rules and understand the structure of homologous series. You will explore isomerism, including structural and stereoisomerism. Mastering these principles helps you to understand more complex organic reactions and apply them in real-world settings such as pharmaceuticals and materials science.

Key concepts include:

• Nomenclature (IUPAC Rules)

• Homologous series and their general formulae

• Formula Types

• Isomerism

Exam Tip: Learn IUPAC priority rules for naming compounds—functional groups take precedence.

Hydrocarbons

Hydrocarbons are vital as fuels, feedstocks, and polymer precursors. In this topic, you will compare alkanes and alkenes. This includes their reactivity, and how cracking converts long-chain hydrocarbons into valuable short-chain hydrocarbons. 

A key focus of this topic is electrophilic addition reactions. These help you to understand how alkenes react to form useful chemicals, such as plastics and fine chemicals.

Key concepts include:

• Alkanes (Saturated Hydrocarbons)

• Alkenes (Unsaturated Hydrocarbons)

• Electrophilic addition mechanism in alkenes

• Cracking

Exam Tip: In addition reactions, the most stable carbocation intermediate forms preferentially.

Alcohols & haloalkanes

Alcohols and haloalkanes are essential as fuels, disinfectants and industrial solvents. Their physical properties and reactivity depend on the hydroxyl (-OH) and halogen (-X) functional groups. This topic explores classification of alcohols and their oxidation reactions. The nucleophilic substitution reactions of haloalkanes are also covered. Understanding these reactions is key to organic synthesis and material production.

Key concepts include:

• Alcohols

• Alcohol Reactions

• Alcohol oxidation including reflux and distillation techniques

• Haloalkanes

Common Mistake: Thinking haloalkanes dissolve well in water—they are mostly insoluble due to weak dipole interactions.

Organic synthesis

Designing and building molecules is a key skill in organic chemistry. In this topic, you will learn how functional groups are interconverted. This involves planning suitable reaction pathways. As part of this, synthetic efficiency is optimised through careful control of reagents and conditions. 

You will also explore multistep synthesis and how retrosynthetic analysis is used to break down complex molecules into simpler precursors. This is an essential approach in drug development and industrial chemistry.

Key concepts include:

• Reaction Pathways

• Functional Group Interconversion

• Synthetic Routes

• Examples of multistep synthesis problems

Exam Tip: Plan synthesis routes step by step, considering possible side reactions.

Analytical techniques (IR and MS)

Analytical chemistry is vital for identifying substances, ensuring drug purity, and monitoring environmental pollutants. Two analytical techniques are infrared (IR) spectroscopy and mass spectrometry (MS). Infrared spectroscopy detects functional groups based on bond vibrations. Mass spectrometry determines molecular mass and fragmentation patterns. These methods allow you to interpret spectra and deduce molecular structures.

Key concepts include:

• Infrared Spectroscopy (IR)

• Low-resolution Mass Spectrometry (MS)

• High-resolution mass spectrometry (HRMS) and its role in molecular formula determination

Common Mistake: Confusing infrared peak positions—learn key functional group absorptions.

Module 5 – Physical chemistry & transition elements

This module includes 4 Practical Activity Groups (PAGs):

• PAG 7: Qualitative Analysis of Organic Functional Groups

• PAG 8: Electrochemical Cells

• PAG 9: Rates of Reaction – Continuous Monitoring

• PAG 10: Rates of Reaction – Initial Rates Method

Reaction rates & equilibrium (quantitative)

Understanding reaction speed and extent is crucial in laboratory work and industry. In this topic, you will explore rate equations, orders of reaction, and how experimental data can determine reaction orders. 

You will also study how equilibrium constants (K_c and K_p) assess the extent of reversible reactions. This can help optimise conditions for maximum efficiency, which is important in pharmaceuticals, energy production, and chemical manufacturing.

Key concepts include:

• Rate of Reaction

• Rate Equation 

• Orders of Reaction, including determining orders from experimental data

• Equilibrium Constants

• Magnitude of K

Common Mistake: Thinking K_c and K_p are affected by pressure, when only temperature affects their values.

pH & buffers

Maintaining pH stability is vital in biology and industry. This topic covers how hydrogen ion concentration determines acidity, K_a values express acid strength, and buffer solutions resist pH changes. You will apply these concepts to real-world scenarios like blood pH regulation and pharmaceutical stability.

Key concepts include:

• pH and Hydrogen Ion Concentration

• Strong vs weak acid pH calculations 

• Acid Dissociation Constant (K_a)

• Buffer Solutions

• Buffer system components

Exam Tip: Buffer pH calculations use the Henderson–Hasselbalch equation: pH = pK_a + log([A^-]/[HA]).

Enthalpy, entropy & free energy

Why do some reactions occur spontaneously while others need an energy input? In this topic, you will learn about enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG), which together determine reaction feasibility. You will also perform associated calculations for ΔH, ΔS, and ΔG and explore how temperature affects spontaneity. These principles are crucial for understanding chemical stability, reaction kinetics, and energy-efficient processes.

Key concepts include:

• Enthalpy Change (ΔH) 

• Entropy (ΔS) – Disorder of a System

• Gibbs Free Energy (ΔG)

• Associated calculations for ΔH, ΔS & ΔG

• Temperature Dependence

Common Mistake: Thinking negative ΔG always means a reaction occurs as this is not true because kinetics may prevent it.

Redox & electrode potentials

Many chemical reactions involve electron transfer. Understanding redox chemistry allows you to predict reaction feasibility and design electrochemical systems. This topic covers electrode potentials (E^o), electrochemical cells, and the applications of the electrochemical series. The use of cell diagrams in describing these systems will also be explored. This can provide insights into battery technology, fuel cells, and corrosion prevention.

Key concepts include:

• Oxidation and Reduction

• Electrode Potentials (E^o)

• Cell Potentials

• Electrochemical Cells

• Cell diagrams 

• Electrochemical series applications​

Common Mistake: Forgetting electrons flow from anode to cathode in electrochemical cells.

Transition elements

Transition metals are some of the most versatile elements in chemistry. They are known for their variable oxidation states, complex ion formation, and catalytic activity. These properties make them essential in industrial processes, medicine, and materials science. They can be used as catalysts in chemical manufacturing, pigments and in biomedical applications.

In this topic, you will explore how transition metals form coloured compounds and how ligands interact to create complex ions. You will also learn why their ability to exist in multiple oxidation states makes them so chemically useful.

Key concepts include:

• Definition of a Transition Metal

• Variable Oxidation States

• Complex Ions & Ligands

• Ligand substitution reactions & their colour changes​

• Catalysis

Exam Tip: Ligand substitution reactions often cause colour changes in transition metal complexes.

Module 6 – Organic chemistry and analysis

This module includes 1 Practical Activity Group (PAG):

• PAG 11: Chromatography

Aromatic compounds

Aromatic compounds, particularly benzene, play a key role in organic chemistry due to their unique stability and reactivity. Unlike alkenes, benzene resists addition reactions because of the delocalised π-electron system. This makes benzene more stable than alkenes, so it reacts via electrophilic substitution. This makes it an essential starting material for pharmaceuticals, dyes, and industrial chemicals. The structure and reactivity of benzene allow you to predict its behaviour and explain its applications in synthesis.

Key concepts include:

• Structure of Benzene

• Electrophilic Substitution Reactions

• Friedel-Crafts acylation & alkylation reactions​

• Aromatic Stability

Common Mistake: Thinking benzene undergoes addition reactions like alkenes, but its stability prevents this.

Carbonyl compounds

Aldehydes and ketones are key functional groups that you come across carbonyl compounds every day, from the aromas in food to key pharmaceutical ingredients. Aldehydes and ketones both contain a C=O bond, but their placement in a molecule affects their reactivity. This topic looks at how aldehydes can be oxidised to carboxylic acids, while ketones resist oxidation under mild conditions. You will also explore nucleophilic addition reactions and how simple chemical tests can distinguish between these two classes of compounds.

Key concepts include:

• Aldehydes vs Ketones

• Reactions of Carbonyls, including explanations of the 2,4-DNP & Tollens’ tests

Exam Tip: Tollens’ and Fehling’s tests only work for aldehydes, not ketones.

Carboxylic acids & esters

Carboxylic acids and esters are everywhere, from vinegar’s sourness to fruity scents in perfumes and food. In this topic, you will explore how carboxylic acids behave as weak acids, reacting with bases, carbonates, and alcohols to form esters. You will also examine how esters can be broken down through hydrolysis. Their unique properties make them useful in everything from medicine to biodiesel production. Understanding these reactions explains key processes in both biological systems and industrial chemistry.

Key concepts include:

• Carboxylic Acids

• Formation of acid chlorides from carboxylic acids​

• Esters

Common Mistake: Thinking carboxylic acids fully ionise—they are weak acids.

Nitrogen compounds

Nitrogen is essential in biological molecules, from proteins to neurotransmitters. This topic explores the chemistry of amines and amino acids. It highlights their role in biochemistry, medicine, and materials science.

You will learn how amines act as weak bases, how amino acids form proteins through peptide bonds, and how these compounds react in acid-base reactions. Understanding nitrogen compounds is key in pharmaceuticals, agriculture, and polymer chemistry.

Key concepts include:

• Amines

• Amino Acids

• Reactions of Amines

• Zwitterions and isoelectric points

Exam Tip: Amino acids exist as zwitterions at their isoelectric point.

Polymers

Polymers are essential in materials like clothing, packaging, and medical implants. These long-chain molecules are built from monomers and are designed for specific uses. In this topic, you will examine addition and condensation polymerisation, how the polymer structure affects its properties, and why some polymers are biodegradable while others persist. Understanding polymer chemistry explains their industrial role and the development of sustainable alternatives

Key concepts include:

• Addition Polymers

• Condensation Polymers

• Biodegradability

• Environmental impact of polymers

Exam Tip: Condensation polymerisation forms ester or amide links.

Organic synthesis

Designing and building new molecules is at the core of organic chemistry. Organic synthesis enables the creation of pharmaceuticals, new materials, and industrial chemicals from simpler compounds. 

In this topic, you will explore reaction pathway planning and how functional groups can be interconverted. This considers synthetic efficiency through careful control of reagents, catalysts, and conditions. Mastering these skills is essential for drug discovery and sustainable chemical manufacturing.

Key concepts include:

• Reaction Pathways

• Functional Group Interconversion

• Synthetic Routes

• Retrosynthetic analysis techniques

Practical Application: Organic synthesis is essential in designing and producing medicines, allowing chemists to develop life-saving drugs with improved effectiveness and fewer side effects.

Chromatography & spectroscopy (NMR)

Determining the structure of unknown compounds is an essential skill in chemistry. In this topic, you will explore chromatographic techniques, such as thin-layer and gas chromatography. You will also learn about NMR spectroscopy, which provides detailed insights into molecular structures. 

You will learn how to interpret carbon-13 and proton NMR spectra. This includes chemical shifts and splitting patterns. This will help you to confidently identify complex organic molecules. This is an essential tool in forensics, pharmaceuticals, and environmental science.

Key concepts include:

• Chromatography

• Nuclear Magnetic Resonance (NMR) Spectroscopy

• Carbon-13 & proton NMR interpretation with chemical shift values

Real-World Application: NMR spectroscopy is widely used in medical imaging (MRI) to analyse soft tissues and detect diseases, while chromatography is essential for drug testing in competitive sports.

What is covered in the OCR A Level in Chemistry A (H432) papers?

There are 3 exam papers for the OCR A Level in Chemistry A (H432) course:

Paper 1: Periodic Table, Elements, & Physical Chemistry

• Exam code: H432/01

• 37% of total qualification

• Duration: 2 hours 15 minutes

• 100 marks

• Assesses content from Modules 1, 2, 3, and 5

Paper 2: Synthesis & Analytical Techniques

• Exam code: H432/02

• 37% of total qualification

• Duration: 2 hours 15 minutes

• 100 marks

• Assesses content from Modules 1, 2, 4, and 6

Paper 3: Unified Chemistry

• Exam code: H432/03

• 26% of total qualification

• Duration: 1 hour 30 minutes

• 70 marks

• Assesses content from all modules (1 to 6)

Revision Resources for OCR A Level in Chemistry A (H432)

To help you prepare for your OCR A Level in Chemistry A (H432) exams, Save My Exams provides a range of high-quality revision resources:

• Revision Notes: Concise, syllabus-aligned summaries breaking down complex topics into easy-to-understand explanations. These notes are ideal for reinforcing key concepts. Try our OCR A Level in Chemistry A Revision notes.

• Exam-Style Topic Questions: A collection of past paper and exam-style questions organised by topic, with detailed, step-by-step solutions from expert teachers. Try our OCR A Level in Chemistry A Exam Questions.

• Past Papers: OCR A Level in Chemistry A (H432) past papers that simulate real exam conditions, helping you refine your problem-solving skills and boost confidence.Try our OCR A Level in Chemistry A Past papers. 

You can access all these resources at Save My Exams - OCR A Level Chemistry A

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References

• AQA A Level Chemistry (7405) Specification

• Edexcel A Level Chemistry (9CH0) Specification

• OCR A Level in Chemistry A (H432) Specification