Chemistry

A-Level Chemistry essential study guide

What actually needs mastering across physical, inorganic and organic chemistry, the calculations and mechanisms that repeat every year, and a weekly routine that fits around the rest of your subjects. Applies to AQA, Edexcel and OCR specifications.

Physical chemistry

The calculation-heavy backbone of the course. Almost every paper rewards clean working and correct units.

  • Amount of substance: moles, concentration, ideal gas equation, percentage yield and atom economy.
  • Energetics: enthalpy changes, Hess cycles, bond enthalpies, and calorimetry including sources of error.
  • Kinetics: rate equations, orders from initial-rate and graphical data, rate-determining step, Arrhenius.
  • Equilibria: Kc and Kp expressions, Le Chatelier reasoning, and how a catalyst affects rate but not position.
  • Acids and bases: strong and weak pH, Ka and pKa, buffers and titration curve shapes for each acid-base pair.
  • Redox and electrode potentials: half equations, cell EMF, feasibility, and electrochemical cells.
  • Thermodynamics: lattice enthalpy, Born-Haber cycles, entropy change and Gibbs free energy feasibility.

Inorganic chemistry

Pattern recognition. Learn the trends first, then attach the specific observations and equations to them.

  • Periodicity: atomic radius, ionisation energy, melting point trends and the reasons behind each.
  • Group 2: reactions with water, solubility trends of hydroxides and sulfates, and their uses.
  • Group 7: trends in boiling point, oxidising ability of halogens, reducing ability of halides, disproportionation.
  • Period 3 oxides: bonding, structure, reaction with water and the resulting pH.
  • Transition metals: variable oxidation states, complex ions, ligand substitution, colour changes and catalysis.
  • Qualitative analysis: the observations for each test, written as an examiner would want them.

Organic chemistry

Mechanisms plus synthesis routes. If you can draw the arrows, most of the mark scheme follows.

  • Nomenclature, isomerism (structural, E/Z, optical) and how to identify chirality quickly.
  • Mechanisms to reproduce from memory: free-radical substitution, electrophilic addition, electrophilic substitution, nucleophilic substitution, nucleophilic addition, nucleophilic addition-elimination, elimination.
  • Functional group conversions: alkene to alcohol to halogenoalkane to nitrile to amine, with reagents and conditions.
  • Carbonyls, carboxylic acids and derivatives: reactions, distinguishing tests, and esterification.
  • Aromatic chemistry: nitration, halogenation, Friedel-Crafts, and why benzene resists addition.
  • Polymers, amino acids and proteins, plus condensation and addition polymer identification.
  • Analysis: mass spectra fragmentation, infrared absorptions, and both proton and carbon-13 NMR interpretation.

A weekly routine that works

Twice a week
One timed calculation set: moles, Kc or pH. Mark with units and significant figures checked separately from the method.
Twice a week
Draw three mechanisms from a blank page, including conditions and intermediates, then check against your notes.
Weekly
One inorganic trend written as a table from memory: trend, reason, exception.
Weekly
Half a past paper, timed. Log the mark scheme phrases you missed, not just the score.
Monthly
Return to the topics you scored worst on and re-test rather than re-read.

Where marks are lost

  • Rounding part-way through a multi-step calculation instead of at the end.
  • Omitting state symbols in equations where the mark scheme requires them.
  • Drawing curly arrows from the wrong place: they start at a lone pair or a bond, never at an atom symbol.
  • Explaining a trend with "it gets bigger" instead of naming shielding, nuclear charge and atomic radius.
  • Describing a colour change without stating both the starting and final colour.

Practise it, don't just read it

Paste a module of your Chemistry notes into Recall Study and get flashcards, a quiz or exam-style questions straight away. Free for three generations a day.

Keep going

FAQs

How should I revise A-Level Chemistry?

Split every session into three parts: recall the definitions and equations, work through calculations without looking at worked examples, and draw mechanisms from memory. Chemistry marks are lost on precision, not on effort.

Which A-Level Chemistry topics are hardest?

Most students find thermodynamics and entropy, electrode potentials, kinetics and rate equations, and organic synthesis routes the hardest. All four are pattern-based, so repeated timed practice beats re-reading.

How much of A-Level Chemistry is maths?

Around 20 percent of the marks are mathematical: moles, titrations, yields, Kc and Kp, pH, rate constants and enthalpy calculations. Practise them under time pressure with correct units and significant figures.

Do I need to memorise organic mechanisms?

Yes. Curly arrows, intermediates and conditions must be reproducible from memory. Learn each mechanism as a story: what attacks what, why, and what leaves.