OCR A A-Level Chemistry revision
Work through OCR A in syllabus order. Each specification point has a short explanation, with equations, calculations and exam warnings where they help.
Start at the beginning or jump to the topic you need
The notes stay close to the OCR A course. Open a topic, check each line, then use the linked Chemistry Help questions when you want to test it.
Module 2: Foundations in Chemistry
2.1.1
Atomic structure and isotopes
Use atomic number, mass number and ionic charge to count particles, then use isotope data and mass spectra to calculate relative masses.
→
2.1.2
Compounds, formulae and equations
Predict ion charges, write ionic formulae, then balance full and ionic equations with the correct state symbols.
→
2.1.3
Amount of substance
Use moles as the link between particles, masses, solutions and gases, then apply balanced-equation ratios to empirical formulae, yields and multi-step calculations.
→
2.1.4
Acids
Recognise the common acids and alkalis, distinguish strong from weak acids, write neutralisation equations and use accurate titration technique and calculations.
→
2.1.5
Redox
Assign oxidation numbers, use them in formulae and names, then track electron transfer and oxidation-state changes through redox reactions.
→
2.2.1
Electron structure
Move from shells to orbitals and sub-shells, then build electron configurations and box diagrams for atoms and s- and p-block ions.
→
2.2.2
Bonding and structure
Connect ionic and covalent bonding to structure, shape, polarity, intermolecular forces and the physical properties you can observe.
→
Module 3: Periodic Table and Energy
3.1.1
Periodicity
Follow electron structure across the periodic table, then use it to explain ionisation energies, metallic and giant covalent structures, and melting-point trends.
→
3.1.2
Group 2
Use the ns² outer configuration to explain Group 2 ions, reactions and the increasing reactivity down the group, then apply the hydroxides and carbonates as bases.
→
3.1.3
The halogens
Use electron structure and intermolecular forces to explain halogen trends, then work through displacement, disproportionation, water treatment and halide tests.
→
3.1.4
Qualitative analysis
Use a short sequence of ion tests, observations and ionic equations to identify common anions and ammonium ions.
→
3.2.1
Enthalpy changes
Read enthalpy signs and profiles, use standard enthalpy terms accurately, then calculate energy changes from calorimetry, bond enthalpies and Hess cycles.
→
3.2.2
Reaction rates
Use collision theory, gradients and Maxwell–Boltzmann distributions to explain rates, then connect catalysts to activation energy and practical rate measurements.
→
3.2.3
Chemical equilibrium
Distinguish dynamic equilibrium from equal concentrations, predict equilibrium shifts, and write and use Kc expressions for homogeneous equilibria.
→
Module 4: Core Organic Chemistry
4.1.1
Basic concepts of organic chemistry
Get the language and drawing conventions secure first: names, formulae, isomers, bond fission and curly arrows turn up throughout organic chemistry.
→
4.1.2
Alkanes
Connect alkane structure to shape, physical properties and low reactivity, then learn the radical-substitution chain mechanism.
→
4.1.3
Alkenes
Use the C=C bond to explain alkene shape, E/Z isomerism and electrophilic addition, then connect addition reactions to polymers.
→
4.2.1
Alcohols
Use hydrogen bonding to explain alcohol properties, then distinguish primary, secondary and tertiary alcohols and learn their main Year 12 reactions.
→
4.2.2
Haloalkanes
Use the polar C–X bond to explain nucleophilic substitution and hydrolysis rates, then connect radical chemistry to ozone depletion.
→
4.2.3
Organic synthesis
Choose the right apparatus and purification sequence, then connect functional groups into short OCR Year 12 synthetic routes.
→
4.2.4
Analytical techniques
Use IR and mass spectra as evidence: identify characteristic bonds, read molecular mass and fragments, then make one structure that fits all the data.
→
Module 5: Physical Chemistry and Transition Elements
5.1.1
Rates of Reaction
Turn experimental rate evidence into orders and rate equations, use graphs and half-life, then connect mechanisms and temperature to the Arrhenius equation.
→
5.1.2
Equilibrium (Kc and Kp)
Work from equilibrium amounts to concentrations or partial pressures, calculate Kc and Kp, and keep a change in equilibrium position separate from a change in the equilibrium constant.
→
5.1.3
Acids, Bases and Buffers
Start with Brønsted–Lowry acids and bases, then work through pH, Kₐ, Kᵥ, weak acids, buffers, titration curves, indicators and pH-meter technique.
→
5.2.1
Lattice Enthalpy
Build Born–Haber and solution cycles, then use ionic charge and radius to explain lattice and hydration enthalpies.
→
5.2.2
Enthalpy and Entropy
Use entropy and Gibbs calculations to decide whether a process is thermodynamically feasible, and see how temperature can change the answer.
→
5.2.3
Redox and Electrode Potentials
Use half-equations and electrode potentials to predict redox reactions, then apply the same ideas to titrations, electrochemical cells and fuel cells.
→
5.3.1
Transition Elements
Start with electron configurations and complex ions, then work through shapes and isomers, ligand substitution, precipitation and redox chemistry.
→
5.3.2
Qualitative Analysis
Use the test sequence and observations to identify anions, ammonium and the common transition-metal ions OCR expects.
→
Module 6: Organic Chemistry and Analysis
6.1.1
Aromatic Compounds
Use the bonding in benzene to explain its reactions, then work through electrophilic substitution, phenol and directing effects.
→
6.1.2
Carbonyl Compounds
Work from the polar C=O bond: oxidise aldehydes, reduce carbonyls, add CN⁻, draw the nucleophilic-addition mechanisms, and use the tests that distinguish aldehydes from ketones.
→
6.1.3
Carboxylic Acids and Esters
Use the –COOH group to predict acid reactions, then follow it through esterification, ester hydrolysis and the acyl-chloride reactions OCR expects in synthesis.
→
6.2.1
Amines
Start with nitrogen’s lone pair: use it to explain basicity and salt formation, then follow ammonia and amines through haloalkane substitution and make aromatic amines from nitroarenes.
→
6.2.2
Amino Acids, Amides and Chirality
Use the –NH₂ and –COOH groups independently: predict their reactions, recognise amides, and then check for chiral centres and enantiomers.
→
6.2.3
Polyesters and Polyamides
Read the link in the polymer chain. Ester and amide links tell you how it formed, how hydrolysis breaks it, and which monomers you need to reconstruct.
→
6.2.4
Carbon–Carbon Bond Formation
Watch the carbon count. OCR uses cyanide chemistry and Friedel–Crafts reactions to build larger carbon skeletons, so each route here is really about spotting where the new C–C bond appears.
→
6.2.5
Organic Synthesis
This is where the course joins up. You need the practical decisions behind making and purifying an organic product, then the reaction knowledge to move through unfamiliar functional groups and multi-stage routes without adding contradictory chemistry.
→
6.3.1
Chromatography and Qualitative Analysis
Here you are using experimental evidence to narrow down an unknown. TLC and gas chromatography give separation evidence; the test-tube reactions then tell you which functional groups are present. Keep observations separate from conclusions — “effervescence” is an observation, “CO₂ formed” is an inference.
→
6.3.2
Spectroscopy (NMR)
NMR gets much easier when you make each signal do one job. Count environments, use chemical shift for the type of environment, integration for how many H, and splitting for neighbours. Then make the final structure earn its place by fitting every piece of evidence.
→
You’ll find OCR A Chemistry past papers and mark schemes on LearnFaster. The paper links open the official exam board versions.