WJEC A-Level Chemistry Active Recall Guide
WJEC · A-Level
WJEC A-Level Chemistry Active Recall Guide
A question-and-answer revision guide for WJEC A-Level Chemistry, built to be worked in three passes rather than read.
- WJEC
- A-Level
- 36 topics
The 3-step active recall method
Re-reading notes is a futile process when your aim is to remember the information and successfully apply it in exam settings. Active recall is the method you use to ensure the information sticks for a long period of time. But even active recall can be futile unless you have a structured way of implementing it. This is where the 3-step active recall method comes in, a structured method that is signature to the Levo Learning guides.
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Step 1
Answer up to 10 questions cold, closed book, even if you are unsure on the topic.
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Step 2
Answer the same questions again, but open book. Write the correct answer down even if it seems pointless.
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Step 3
Repeat as step 1 and answer the questions closed book again.
Worked across the WJEC A-Level Chemistry specification, one subtopic at a time.
The subject, and what is assessed
WJEC A-Level Chemistry is assessed by five units, two taken at AS and three at A2. The two AS units each last 1 hour 30 minutes and are worth 20% of the A-Level. A2 Unit 3 and A2 Unit 4 each last 1 hour 45 minutes and are worth 25%. A2 Unit 5 is a practical examination worth 10%. AS content remains examinable at A2, so first year material stays in use through the second year.
| Paper | Covers | Length | Weighting |
|---|---|---|---|
| AS Unit 1 | 1 hour 30 minutes | 20% | |
| AS Unit 2 | 1 hour 30 minutes | 20% | |
| A2 Unit 3 | 1 hour 45 minutes | 25% | |
| A2 Unit 4 | 1 hour 45 minutes | 25% | |
| A2 Unit 5 | Practical examination | 10% |
Memorisation, then application
Marks are given for applying content to the question that has been set, which cannot happen while the content is still being looked up. Step 1 shows what is actually held. Step 2 puts the correct wording in front of you while the gap is still fresh. Step 3 repeats the cold test, and the difference between the first and third attempt is the part that has moved.
Every question in the guide is paired with its answer in the same document, so step 2 is done from the guide itself rather than from a separate set of notes.
What is inside the guide
Questions are grouped by topic and then by subtopic, following the WJEC specification. Open a topic to see its subtopics.
Formulae and Equations6 subtopics
- Charges on common ions10
- Building formulae for ionic and molecular compounds12
- Assigning oxidation numbers12
- Using oxidation numbers to follow redox changes9
- Balancing equations and using state symbols13
- Ionic and half equations15
Basic Ideas About Atoms9 subtopics
- Radioactive decay and nuclear equations22
- Alpha, beta and gamma radiation14
- Half-life, dating and the uses of radioisotopes: half-life of radioactive decay11
- Half-life, dating and the uses of radioisotopes: adverse consequences for living cells14
- Ionisation energies and electronic structure27
- Orbitals and the filling of sub-shells18
- Atomic spectra and the energy of light: atomic emission spectrum of the hydrogen atom12
- Atomic spectra and the energy of light: relationship between energy and frequency14
- Atomic spectra and the energy of light: significance of the frequency12
Chemical Calculations12 subtopics
- Relative masses and the mass spectrometer: relative atomic11
- Relative masses and the mass spectrometer: how a mass spectrometer works15
- Relative masses and the mass spectrometer: molecular ion12
- The mole, the Avogadro constant and molar mass: relative mass terms and simple mass spectra15
- The mole, the Avogadro constant and molar mass: moles and percentage composition by mass8
- Empirical and molecular formulae17
- Concentration, solubility and titration calculations: concentration in mol dm-3 and in g dm-311
- Concentration, solubility and titration calculations: stoichiometry and the limiting reagent8
- Concentration, solubility and titration calculations: titration calculations and estimating a titre13
- Gas volumes and the ideal gas equation24
- Yield, atom economy and experimental uncertainty: concepts of atom economy and percentage yield13
- Yield, atom economy and experimental uncertainty: how to estimate the percentage error14
Bonding8 subtopics
- Ionic bonds and covalent bonds: ionic bonding in terms of ion formation13
- Ionic bonds and covalent bonds: covalent bonding and forces16
- Electronegativity, polarity and in-between bonds: concepts of electronegativity and bond polarity12
- Electronegativity, polarity and in-between bonds: forces10
- Forces between molecules23
- Hydrogen bonding19
- Shapes of molecules and ions: VSEPR principle and its use8
- Shapes of molecules and ions: bond angles associated with linear24
Solid Structures5 subtopics
- Ionic crystals: sodium chloride and caesium chloride14
- Giant covalent structures: diamond and graphite16
- Simple molecular solids: iodine and ice15
- Metals and the electron sea13
- Using structure to explain physical properties19
The Periodic Table13 subtopics
- How the Periodic Table is organised26
- Oxidation and reduction as electron transfer20
- Trends across periods and down groups22
- Group 2: reactions, trends and the reasons behind them, reactions with oxygen, water and dilute acid13
- Group 2: reactions, trends and the reasons behind them, trends down the group12
- Group 2: reactions, trends and the reasons behind them, thermal stability of the carbonates12
- Group 2: reactions, trends and the reasons behind them, oxides and hydroxides23
- Identifying ions, making salts and gravimetric analysis: identifying cations with sodium hydroxide26
- Identifying ions, making salts and gravimetric analysis: preparing a soluble salt from an acid19
- Group 7: the halogens, physical properties and the trend in volatility11
- Group 7: the halogens, reactions of the halogens with metals12
- Group 7: the halogens, displacement reactions and the trend13
- Group 7: the halogens, halide ions as reducing agents, uses of chlorine and the chlorate equilibrium34
Simple Equilibria and Acid-Base Reactions6 subtopics
- Reversible reactions and dynamic equilibrium15
- Le Chatelier's principle and shifting the position of equilibrium17
- The equilibrium constant Kc16
- Acids, bases, salts and neutralisation15
- pH, strong acids and weak acids20
- Acid-base titrations and their calculations22
Thermochemistry5 subtopics
- Enthalpy changes and their definitions16
- Calculating enthalpy changes from experimental measurements16
- Determining enthalpy changes in the laboratory15
- Hess's law and energy cycles18
- Average bond enthalpies15
Rates of Reaction6 subtopics
- Collision theory and the conditions that change rate17
- Measuring rate and relating it to concentration17
- Energy profiles and activation energy15
- Temperature and the Boltzmann distribution15
- Catalysts and how they work18
- Following reactions in the laboratory22
The Wider Impact of Chemistry3 subtopics
- Social and economic consequences of chemical manufacture and energy supply10
- Environmental consequences of chemical processes and energy production10
- Green chemistry and sustainable practice16
Organic Compounds5 subtopics
- Drawing and reading organic structures16
- Naming organic compounds20
- Chain length, functional groups and physical properties16
- Structural isomerism16
- Electrophiles, nucleophiles, radicals and bond fission17
Hydrocarbons10 subtopics
- Alkane bonding, combustion and fossil fuels: combustion reaction of alkanes and benefits20
- Alkane bonding, combustion and fossil fuels: combustion calculations and acid rain8
- Radical substitution of alkanes17
- The C=C bond and why alkenes are reactive25
- E-Z isomerism in alkenes15
- Electrophilic addition, Markovnikov's rule and testing for alkenes: mechanism of electrophilic addition14
- Electrophilic addition, Markovnikov's rule and testing for alkenes: Markovnikov's rule and the bromine water test17
- Electrophilic addition, Markovnikov's rule and testing for alkenes: testing for a C=C bond11
- Hydrogenation and addition polymers: conditions required9
- Hydrogenation and addition polymers: nature of addition polymerisation21
Halogenoalkanes7 subtopics
- Nucleophilic substitution by hydroxide ions17
- Elimination to form alkenes15
- Reactivity of the carbon-halogen bond and the silver nitrate test28
- Uses of halogenoalkanes, CFCs and the ozone layer: uses of halogenoalkanes and CFCs9
- Uses of halogenoalkanes, CFCs and the ozone layer: radical mechanism8
- Uses of halogenoalkanes, CFCs and the ozone layer: replacements for CFCs11
- Heating under reflux in the laboratory15
Alcohols and Carboxylic Acids11 subtopics
- Two routes to ethanol: hydration and fermentation, hydration of ethene9
- Two routes to ethanol: hydration and fermentation, fermentation8
- Two routes to ethanol: hydration and fermentation, comparing the two routes on rate15
- Classifying alcohols and dehydrating them28
- Oxidising alcohols to aldehydes, ketones and acids25
- Chemical tests for alcohols and carboxylic acids18
- Carboxylic acids, bases and salts20
- Making an ester and separating it by distillation: esterification8
- Making an ester and separating it by distillation: carrying out the preparation8
- Making an ester and separating it by distillation: separating and purifying8
- Making an ester and separating it by distillation: yield8
Instrumental Analysis4 subtopics
- Reading a mass spectrum26
- Infrared spectra and functional groups21
- NMR spectra and atomic environments27
- Putting the three techniques together12
Redox and Standard Electrode Potential5 subtopics
- Electron transfer and oxidation numbers23
- Half-equations, half-cells and cell diagrams28
- The hydrogen electrode and standard electrode potentials21
- Cell EMF and the feasibility of reactions26
- The hydrogen fuel cell17
Redox Reactions5 subtopics
- Building ion-electron half-equations19
- Combining half-equations into full equations15
- Copper, iodide and thiosulfate18
- Carrying out and calculating a redox titration: procedure for a manganate titration13
- Carrying out and calculating a redox titration: redox titration calculations16
Chemistry of the P-Block13 subtopics
- Amphoteric behaviour of aluminium and lead17
- Stability of oxidation states down Groups 3, 4 and 5: increasing stability of the inert pair cations13
- Stability of oxidation states down Groups 3, 4 and 5: change in relative stability13
- Valence shells that break the octet rule: how some Group 3 elements can form compounds13
- Valence shells that break the octet rule: structure and bonding in Al2Cl6 and formation13
- Boron nitride: two structures, two sets of properties15
- Group 4 oxides and chlorides, and lead in solution: structure14
- Group 4 oxides and chlorides, and lead in solution: hydrolysis of the Group 4 chlorides9
- Group 4 oxides and chlorides, and lead in solution: chloride hydrolysis and lead(II) precipitates8
- Group 4 oxides and chlorides, and lead in solution: distinguishing lead from silver ions11
- Chlorine, chlorate and the sodium halides: chlorine with water and with cold and hot alkali15
- Chlorine, chlorate and the sodium halides: bleaching and bactericidal action of Cl212
- Chlorine, chlorate and the sodium halides: differences in behaviour of NaCl15
Chemistry of the D-Block Transition Metals10 subtopics
- Variable oxidation states and the colours of their solutions: how the d-block elements attain various13
- Variable oxidation states and the colours of their solutions: most important oxidation states of Cr16
- Complex ions: ligands, coordination number and shape17
- Why transition metal complexes are coloured18
- Ligand exchange and changes in coordination number28
- Transition metals as catalysts: why transition metals10
- Transition metals as catalysts: variable oxidation state12
- Transition metals as catalysts: heterogeneous catalysis14
- Transition metals as catalysts: surface area12
- Transition metal ions with aqueous hydroxide17
Chemical Kinetics5 subtopics
- Following a reaction by sampling and quenching19
- Finding the order of a reaction from experimental results20
- The rate equation and the rate constant17
- Rate-determining steps and reaction mechanisms25
- Temperature, catalysts and the Arrhenius equation23
Enthalpy Changes for Solids and Solutions4 subtopics
- Defining the enthalpy changes19
- Born-Haber cycles for ionic compounds17
- Dissolving: lattice breaking against hydration17
- What the enthalpy of formation says about stability14
Entropy and Feasibility of Reactions5 subtopics
- Entropy as the freedom of particles14
- Comparing entropy across states and reactions14
- Calculating entropy changes15
- Gibbs free energy change16
- Feasibility, temperature and spontaneous endothermic change19
Equilibrium Constants4 subtopics
- Writing equilibrium constant expressions and deriving their units21
- Calculating Kc and equilibrium amounts17
- Partial pressures and Kp calculations16
- Temperature, magnitude and the position of equilibrium22
Acid-Base Equilibria10 subtopics
- Proton transfer and conjugate pairs14
- Strong and weak acids: Ka and pKa15
- Water, Kw and the pH scale14
- pH calculations for acids and alkalis: how to use pH14
- pH calculations for acids and alkalis: strong bases, dilution and mixtures9
- Buffers: how they hold pH steady and why they matter28
- Titrations: curve shapes, salt pH and choosing an indicator, pH curve shapes for strong and weak acids and bases10
- Titrations: curve shapes, salt pH and choosing an indicator8
- Titrations: curve shapes, salt pH and choosing an indicator, how an indicator works and choosing one10
- Titrations: curve shapes, salt pH and choosing an indicator, using a pH probe12
Stereoisomerism4 subtopics
- Structural isomerism and stereoisomerism compared13
- E-Z isomerism and the priority rules16
- Chiral centres, enantiomers and racemic mixtures21
- Optical activity and plane-polarised light14
Aromaticity4 subtopics
- Benzene: shape, bonding and delocalisation15
- Aromatic stability and resistance to addition14
- Electrophilic substitution: nitration, halogenation and alkylation20
- How ring and substituent affect each other13
Alcohols and Phenols4 subtopics
- Making primary and secondary alcohols16
- Reactions of primary and secondary alcohols17
- Phenol: acidity and characteristic reactions18
- Recognising a phenol13
Aldehydes and Ketones6 subtopics
- Making aldehydes and ketones from alcohols15
- Distinguishing aldehydes from ketones15
- Reduction of carbonyl compounds with NaBH₄12
- Nucleophilic addition of hydrogen cyanide17
- 2,4-dinitrophenylhydrazine as a test for a carbonyl group13
- The triiodomethane test14
Carboxylic Acids and Their Derivatives7 subtopics
- Comparing the acidity of carboxylic acids, phenols, alcohols and water16
- Making carboxylic acids by oxidation24
- Reduction and decarboxylation of carboxylic acids: reduction of carboxylic acids using LiAlH₄10
- Reduction and decarboxylation of carboxylic acids: decarboxylation of carboxylic acids12
- Esters and acid chlorides25
- Turning acids and halogenoalkanes into amides and nitriles26
- Hydrolysis and reduction of nitriles and amides27
Amines7 subtopics
- Preparing aliphatic and aromatic amines28
- The basicity of amines17
- Ethanoylation of primary amines14
- Primary amines and cold nitric(III) acid17
- Coupling reactions and azo dyes: coupling of benzenediazonium salts with phenols11
- Coupling reactions and azo dyes: role of the -N=N- chromophore in azo dyes13
- The origin of colour15
Amino Acids, Peptides and Proteins5 subtopics
- Structure and classification of α-amino acids15
- Zwitterions, amphoteric character and physical properties17
- Peptide links: dipeptides, polypeptides and proteins23
- Levels of protein structure and the bonds that hold them16
- Proteins at work: enzymes and biological function15
Organic Synthesis and Analysis10 subtopics
- Planning a synthesis as a sequence of reactions24
- Working up a preparation: separation and purification21
- Melting temperature as a test of purity13
- Addition and condensation polymerisation: polyesters and polyamides25
- Polymers: hydrolysis, properties and identifying repeat units8
- High-resolution ¹H NMR and the elucidation of structure: low- and high-resolution proton NMR10
- High-resolution ¹H NMR and the elucidation of structure: chemical shift, TMS, solvents and D₂O exchange9
- High-resolution ¹H NMR and the elucidation of structure: combining mass spectra and NMR to identify compounds9
- High-resolution ¹H NMR and the elucidation of structure: combining NMR with mass spectrometry9
- Chromatography and the composition of mixtures24
Practical Skills and Techniques8 subtopics
- Measuring mass, volume, time and temperature19
- Standard solutions and titration technique20
- Indicators and acid-base titration curves19
- Heating, refluxing, distilling and purifying: Heating11
- Heating, refluxing, distilling and purifying: purifying12
- Melting temperature, chromatography and pH measurement21
- Electrochemical cells, rate methods and working safely: Electrochemical cells9
- Electrochemical cells, rate methods and working safely: rate methods and working safely19
Planning, Analysis and Evaluation6 subtopics
- Planning an investigation and controlling variables19
- Recording observations and presenting data15
- Graphs, gradients and processing data19
- Errors, uncertainty, accuracy and precision19
- Evaluating a method and suggesting improvements17
- Research and referencing12
Core Experiments and Their Chemistry7 subtopics
- Gravimetric and acid-base analysis23
- Enthalpy and rate experiments: Enthalpy10
- Enthalpy and rate experiments: rate experiments11
- Redox titrations and electrochemical cells18
- Equilibrium constants and following a titration with a pH probe16
- Organic synthesis, separation and identification: Organic synthesis15
- Organic synthesis, separation and identification: identification tests and chromatography8
Mathematical Skills in Chemistry17 subtopics
- Units, standard form and proportion in chemical calculation: volume, equilibrium, rate and energy units16
- Units, standard form and proportion in chemical calculation: standard form13
- Units, standard form and proportion in chemical calculation: proportion13
- Units, standard form and proportion in chemical calculation: checking answers, buffers, rate constants and units22
- Significant figures, means and uncertainty in experimental data: significant figures in multiplication13
- Significant figures, means and uncertainty in experimental data: relative atomic mass as a weighted mean17
- Significant figures, means and uncertainty in experimental data: absolute and percentage uncertainty14
- Symbols, rearranging equations and logarithms: chemical symbols and what each one asserts13
- Symbols, rearranging equations and logarithms: rearranging an equation14
- Symbols, rearranging equations and logarithms: substituting into equations for Kc, enthalpy and pH21
- Symbols, rearranging equations and logarithms: logarithms, the Arrhenius equation and rearranging formulae12
- Graphs: plotting, gradients, intercepts and tangents, reading a spectrum12
- Graphs: plotting, gradients, intercepts and tangents, reaction order from data and plotting good graphs19
- Graphs: plotting, gradients, intercepts and tangents, Arrhenius plots, zero-order graphs and tangents12
- Graphs: plotting, gradients, intercepts and tangents, initial rates from tangents and interpreting graphs16
- Shape, symmetry and three-dimensional structure: Shape23
- Shape, symmetry and three-dimensional structure: symmetry21
Sample questions
Taken from the WJEC A-Level Chemistry guide. Answer each one closed book first, then open the answer.
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Formulae and Equations
Why does every metal in Group 1 form an ion with a single positive charge?
Show the answer
A Group 1 atom has one electron in its outermost shell. Losing that electron leaves the ion with the stable electron arrangement of the preceding noble gas, and because one negatively charged electron has gone the ion carries a charge of 1+, as in Na⁺ and K⁺. -
Basic Ideas About Atoms
Why is radioactive decay described as random and spontaneous?
Show the answer
It is impossible to predict which particular nucleus in a sample will decay next or when, so the process is random. It is spontaneous because it happens of its own accord, without needing to be started, and its rate cannot be altered by heating, by pressure or by putting the element into a different chemical compound. -
Chemical Calculations
Why do relative atomic masses have no units?
Show the answer
Each one is a ratio of two masses, the mass of an atom compared with one twelfth of the mass of a carbon-12 atom. Dividing a mass by a mass leaves a pure number. -
Bonding
What actually holds the particles together in an ionic crystal?
Show the answer
The electrostatic attraction between oppositely charged ions holds the crystal together. Each ion attracts every oppositely charged ion around it, so the attraction extends in all directions throughout the whole lattice rather than being confined to pairs of ions. -
Solid Structures
How are the ions arranged in a crystal of sodium chloride?
Show the answer
The ions form a giant cubic lattice in which every sodium ion is surrounded by six chloride ions at the corners of an octahedron and every chloride ion is surrounded by six sodium ions in the same way. The pattern repeats in all three dimensions, so the crystal is a single giant structure with no molecules in it. -
The Periodic Table
On what property are the elements of the modern Periodic Table placed in order?
Show the answer
They are placed in order of increasing atomic number, that is, the number of protons in the nucleus of an atom of the element. -
Simple Equilibria and Acid-Base Reactions
What does the ⇌ sign in an equation tell you?
Show the answer
It tells you the reaction is reversible, so a forward and a backward reaction are both taking place in the same vessel. -
Thermochemistry
What is meant by the enthalpy change of a reaction?
Show the answer
The enthalpy change of a reaction is the heat energy taken in or given out when the reaction occurs at constant pressure, for the molar quantities shown in the balanced equation.
Questions about this guide
How do you use active recall for WJEC A-Level Chemistry?
Answer up to 10 questions cold and closed book. Answer the same questions again open book, writing the correct answer down. Then answer them closed book one more time. The difference between the first and third attempt is what has moved into recall.
How is WJEC A-Level Chemistry assessed?
WJEC A-Level Chemistry is assessed by 5 components: AS Unit 1 (1 hour 30 minutes, 20%); AS Unit 2 (1 hour 30 minutes, 20%); A2 Unit 3 (1 hour 45 minutes, 25%); A2 Unit 4 (1 hour 45 minutes, 25%); A2 Unit 5, practical examination (10%).
What topics does the WJEC A-Level Chemistry active recall guide cover?
It covers Formulae and Equations, Basic Ideas About Atoms, Chemical Calculations, Bonding, Solid Structures, The Periodic Table, Simple Equilibria and Acid-Base Reactions, Thermochemistry, Rates of Reaction, The Wider Impact of Chemistry, Organic Compounds, Hydrocarbons, Halogenoalkanes and Alcohols and Carboxylic Acids. The full list is set out on this page.
Is the WJEC A-Level Chemistry guide a PDF?
Yes. It is a digital PDF sent to the email address on your order after purchase. Check the address is correct at checkout, and check junk or spam if it has not arrived.
Does the guide include the answers?
Yes. Every question has its answer in the same document, grouped by topic, so step 2 of the method is done from the guide.
WJEC A-Level Chemistry Active Recall Guide
Every question paired with its answer, grouped by topic, ready to work in three passes.