Key term
OCR A-Level Chemistry H432
Foundations in Chemistry
Topic overviewAtomic structure, isotopes and counting sub-atomic particlesRelative isotopic, atomic, molecular and formula massPredicting ionic charges and the common ionsWriting formulae, balanced equations and ionic equationsThe mole, molar mass and the Avogadro constantEmpirical and molecular formulae, and hydrated saltsGas volumes, concentration and the ideal gas equationStoichiometry, percentage yield and atom economyApparatus, and why high atom economy mattersMathematical skills and measuring mass, volume and gasAcids, alkalis, dissociation and neutralisationPreparing a standard solutionCarrying out a titration and its calculationsPlanning an experiment: variables, apparatus and recording resultsPractical safety, heating and filtrationUncertainty, percentage error, precision and accuracyEvaluating results: anomalies, conclusions, limitations and improvementsAssigning oxidation numbersRoman numerals in names, and the chlorate and nitrate ionsOxidation, reduction and metals reacting with acidsRedox equations and identifying what is oxidisedShells, orbitals and sub-shellsThe order in which sub-shells fillWriting electron configurations for atoms and ions
Bonding and Structure
Topic overviewIonic bonding and the properties of ionic compoundsCovalent and coordinate bondingLone pairs, bonding pairs and average bond enthalpyElectron pair repulsion theory, linear and trigonal planar shapesTetrahedral, pyramidal and non-linear shapes and their bond anglesOctahedral shapes, ions, and drawing molecules in three dimensionsElectronegativity, polar bonds and polar moleculesPermanent and induced dipoles, and hydrogen bondingSimple molecular lattices and why they melt easilySolubility and conductivity of simple molecular compounds
Periodic Table and Energy
Topic overviewPeriodicity and the electron configurations of periods 2 and 3The blocks, and first and successive ionisation energiesMetallic and giant covalent structures and their propertiesGroup 2 reactions with oxygen, water and acidsIonisation energy down Group 2 and the alkalinity of the hydroxidesUses of Group 2 compounds in agriculture and medicineThe halogens: boiling points, London forces and reactivityHalogen displacement reactions and the colours seenDisproportionation and the chlorination of waterTesting for halide ions with silver nitrate and ammoniaTesting for carbonate, sulfate and halide ionsTesting for ammonium ions and the order of the testsConcentration, pressure and measuring reaction rateCatalysts and their industrial importanceThe Boltzmann distribution, temperature and catalysts
Enthalpy Changes
Topic overviewExothermic and endothermic reactions and enthalpy profilesStandard conditions and the standard enthalpy changesBond enthalpies, q = mcΔT and calorimetryCalculating enthalpy change from bond enthalpiesWhy average bond enthalpies give only an approximationHess' law and enthalpy cycles from combustion and formation dataWorking through an enthalpy cycle and the sign conventionsCalorimetry and correcting for heat loss
Chemical Equilibrium
Basic Concepts of Organic Chemistry
Topic overviewIUPAC nomenclature and the alkyl groupsGeneral, structural, displayed and skeletal formulaeHomologous series, functional groups and saturationStructural isomers, bond fission and curly arrowsChain, position and functional group isomerismCurly arrows, homolytic and heterolytic fissionNucleophiles, electrophiles, radicals and the mechanism steps
Core Organic Chemistry
Topic overviewAlkanes: bonding, shape and boiling pointsCombustion of alkanes and their reaction with halogensThe radical substitution mechanism and its limitationsAlcohols: polarity, solubility and classificationOxidation, dehydration and substitution reactions of alcoholsHydrolysis of haloalkanes and comparing the ratesNucleophilic substitution and carbon-halogen bond strengthCFCs, radicals and the catalytic destruction of ozoneCombining analytical techniques to identify a compound
Alkenes
Topic overviewAlkenes: the double bond, sigma and pi bonding, and shapeE/Z and cis-trans isomerism in alkenesHydrogenation, halogenation and hydration of alkenesElectrophilic addition, carbocation stability and Markownikoff's ruleAddition polymerisation and repeat unitsWaste polymers, and biodegradable and photodegradable alternatives
Organic Synthesis
How Fast?
Topic overviewRate equations, order and the rate constantDeducing orders and finding the units of kWhat the rate equation reveals about the mechanismConcentration-time graphs and continuous monitoringHalf-life and the rate constant of a first-order reactionRate-concentration graphs and the initial rates methodClock reactions, colorimetry and analysing kinetic graphsThe rate-determining step and testing a proposed mechanismTemperature, the rate constant and the Arrhenius equationThe ln k against 1/T graph and finding the activation energy
Physical Chemistry and Transition Elements
Topic overviewMole fraction, partial pressure and ICE tablesKc and Kp expressions, their units and calculationsWhat changes the equilibrium constant, and the reaction quotientLattice enthalpy and the Born-Haber cycleEnthalpy of solution and hydration, and the effect of ionic charge and sizeEntropy and calculating entropy changeGibbs free energy and thermodynamic feasibility
Acids, Bases and Buffers
Topic overviewBrønsted-Lowry acids and bases and their reactionsKa, pKa, pH and the ionic product of waterCalculating the pH of strong acids, strong bases and weak acidspH and hydrogen ion concentrationWhat a buffer is and how it resists a change in pHBuffer calculations and the buffer that controls blood pHTitration curves, choosing an indicator and using a pH meterpH titration curves for the four acid-base combinationsHow an indicator works and choosing the right one
Redox and Electrode Potentials
Topic overviewOxidising and reducing agents, and balancing half-equationsCombining half-equations and using oxidation numbersRedox titrations and their calculationsStandard electrode potentials and setting up half-cellsThe electrochemical series and predicting feasibilityStorage cells and fuel cells
Transition Elements
Topic overviewLigands, complex ions and coordination numberElectron configurations from Sc to Zn, and which are transition elementsVariable oxidation states, coloured ions and catalysisThe shapes of complexes, stereoisomerism and cisplatinLigand substitution, haemoglobin and the copper complexesHydroxide precipitates of iron, manganese and chromiumRedox interconversions of iron, chromium and copperWhy ligand substitution happens and the changes it causesPrecipitation reactions written as aqua complexesDissolving hydroxides in excess ammonia and distinguishing the ions
Aromatic Compounds
Topic overviewThe delocalised model of benzene and the evidence for itNitration, halogenation and Friedel-Crafts reactions of benzeneThe reactions of phenol, and directing effectsElectrophilic substitution and directing effectsPhenol: acidity, bromination and nitrationWhy phenol is more reactive than benzene, and planning a synthesis
Organic Chemistry and Analysis
Topic overviewOxidation and reduction of carbonyls, and the addition of HCNThe nucleophilic addition mechanism2,4-DNPH and Tollens' reagentCarboxylic acids: solubility and reactions with metals, carbonates and basesEsterification and the hydrolysis of estersAcyl chlorides and their reactions with alcohols, amines and ammoniaAmines as bases, and preparing aliphatic aminesSecondary and tertiary amines, and preparing aromatic aminesAmino acids, their reactions, and amidesOptical isomerism and identifying a chiral centreCondensation polymerisation and the ester and amide linkagesHydrolysing condensation polymers and telling them from addition polymersNitriles from haloalkanes and from carbonyl compoundsFriedel-Crafts reactions and lengthening the carbon chainThin-layer and gas chromatography, Rf values and retention timesTest-tube tests for the organic functional groupsTests for the inorganic ions and interpreting chromatograms
Spectroscopy
Topic overviewCarbon-13 and proton NMR: peaks, chemical shift and integrationSpin-spin splitting and predicting a spectrumTMS, deuterated solvents and the D₂O shakeCombining elemental analysis, mass spectrometry, IR and NMRMolecular formula from the molecular ion, and fragmentation lossesWhat IR and NMR each contribute to a structureInfrared absorption, global warming and breathalysersA systematic approach and the degree of unsaturation
Core Organic Chemistry
- 9 subtopics
- 15 things to know
- Components 02 and 03
What Core Organic Chemistry covers
The three families that carry most of the reactions: alkanes and radical substitution, alcohols and their oxidation, and haloalkanes with nucleophilic substitution, ending in the CFC and ozone story and how analytical techniques are combined.
Where it is assessed
Components 02 and 03
Synthesis and Analytical Techniques, then the unified paper.
Check the OCR specification ↗The 9 subtopics
Each one has its own page.
- Alkanes: bonding, shape and boiling pointsRecall questions on saturation and σ-bonding, the tetrahedral shape and its angle, and why boiling point rises with chain length and falls with branching.Open →
- Combustion of alkanes and their reaction with halogensRecall questions on the products of complete and incomplete combustion, why carbon monoxide is dangerous, and the conditions under which alkanes react with halogens.Open →
- The radical substitution mechanism and its limitationsRecall questions on initiation, propagation and termination, why ultraviolet light is needed, and why the reaction is of limited use in synthesis.Open →
- Alcohols: polarity, solubility and classificationRecall questions on why alcohols are polar and hydrogen bond, why short-chain alcohols dissolve, their low volatility, and primary, secondary and tertiary classification.Open →
- Oxidation, dehydration and substitution reactions of alcoholsRecall questions on the conditions that give an aldehyde rather than a carboxylic acid, why tertiary alcohols resist oxidation, dehydration, and substitution to a haloalkane.Open →
- Hydrolysis of haloalkanes and comparing the ratesRecall questions on the product of hydrolysis by aqueous alkali, and on the silver nitrate experiment that compares the rates for the different halogens.Open →
- Nucleophilic substitution and carbon-halogen bond strengthRecall questions on the mechanism step by step, and on why the C-F bond is hardest and the C-I bond easiest to break.Open →
- CFCs, radicals and the catalytic destruction of ozoneRecall questions on the homolytic fission of a CFC by ultraviolet light, the two steps of the catalytic cycle, why the chlorine radical is a catalyst, and how the science shaped policy.Open →
- Combining analytical techniques to identify a compoundRecall questions on what infrared, mass spectrometry, elemental analysis, NMR and simple test-tube reactions each contribute, and why one technique alone is not enough.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
Why are alkanes resistant to polar reagents, what forms on complete combustion, and what are the three stages of radical substitution?
Process
What happens in the initiation stage of radical substitution, why is ultraviolet light needed, and what happens in the termination stage?
Key term
Why are alcohols less volatile than alkanes of similar mass, and what defines a secondary and a tertiary alcohol?
Numbers
How is a primary alcohol oxidised to an aldehyde, what conditions oxidise it fully to a carboxylic acid, and what does [O] represent?
Numbers
How many [O] are needed to oxidise a primary alcohol to a carboxylic acid, what is the general equation, and what forms when a secondary alcohol is heated with acidified dichromate?
Key term
What type of reaction occurs when an alcohol is heated with concentrated phosphoric acid or sulfuric acid?
Process
What happens to the halogen when a haloalkane is hydrolysed by aqueous alkali, what organic product forms, and what happens to the released halide ion in the silver nitrate test?
Key term
What is a nucleophile, which carbon is it attracted to, and what acts as the nucleophile in alkaline hydrolysis?
Process
What does the second curly arrow show in nucleophilic substitution of a haloalkane, what becomes of the halogen, and why is the C–F bond hardest to break?
Process
Why does the C-I bond break most readily, and how does bond strength relate to the rate of hydrolysis?
Key term
What structural information can mass spectrometry provide when identifying organic compounds?
Numbers
What information does elemental analysis provide about an organic compound?
Process
Why does radical substitution give a mixture of products, and what happens to a halogen molecule when it absorbs ultraviolet light?
Numbers
What are the equations for the two steps in the catalytic destruction of ozone by chlorine radicals, and what is the overall equation?
Take Core Organic Chemistry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Homolytic fission vs Heterolytic fission
Homolytic fission: bond breaking with one electron going to each atom. Heterolytic fission: bond breaking with both electrons going to one atom.
Nucleophilic substitution vs Elimination
Nucleophilic substitution: an electron-pair donor replacing an atom or group. Elimination: atoms or groups leaving and a multiple bond forming.
Infrared spectroscopy vs Mass spectrometry
Infrared spectroscopy: analysis using absorption caused by bond vibrations. Mass spectrometry: analysis using mass-to-charge ratios of ionised particles.
Questions from this topic
Each one with the model answer underneath.
- 1
What does it mean for alkanes to be described as saturated hydrocarbons?
Model answer
They contain only single bonds between carbon atoms.
- 2
What type of bond is formed between carbon atoms and between carbon and hydrogen atoms in alkanes?
Model answer
σ-bonds (sigma bonds).
- 3
How are σ-bonds in alkanes formed in terms of orbital overlap?
Model answer
By the direct overlap of orbitals between the bonding atoms along the internuclear axis.
- 4
Why is free rotation possible around C–C single bonds in alkanes?
Model answer
Because σ-bonds have electron density that is symmetrical about the internuclear axis.
- 5
What is the shape around each carbon atom in an alkane?
Model answer
Tetrahedral.
- 6
What is the approximate bond angle around a carbon atom in an alkane?
Model answer
Approximately 109.5°.
What is inside Levo
Six ways to work the same material.
Core Organic Chemistry revision questions
- What does Core Organic Chemistry cover in OCR A-Level Chemistry?
- 9 subtopics: alkanes: bonding, shape and boiling points, combustion of alkanes and their reaction with halogens, the radical substitution mechanism and its limitations, alcohols: polarity, solubility and classification, oxidation, dehydration and substitution reactions of alcohols, hydrolysis of haloalkanes and comparing the rates, nucleophilic substitution and carbon-halogen bond strength, cfcs, radicals and the catalytic destruction of ozone and combining analytical techniques to identify a compound. Each one has its own page with questions and model answers.
- How is Core Organic Chemistry organised?
- By the OCR H432 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Core Organic Chemistry, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.