Numbers
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
Basic Concepts of Organic Chemistry
- 7 subtopics
- 13 things to know
- Components 02 and 03
What Basic Concepts of Organic Chemistry covers
The language of organic chemistry: IUPAC naming, the four ways a structure is written, homologous series and functional groups, the three kinds of structural isomerism, and the curly-arrow conventions used in every mechanism that follows.
Where it is assessed
Components 02 and 03
Synthesis and Analytical Techniques, then the unified paper.
Check the OCR specification ↗The 7 subtopics
Each one has its own page.
- IUPAC nomenclature and the alkyl groupsRecall questions on finding and numbering the longest chain, building the name, and the first ten alkanes and their alkyl groups.Open →
- General, structural, displayed and skeletal formulaeRecall questions on what each type of formula shows, reading a skeletal formula, and when each is the right one to use.Open →
- Homologous series, functional groups and saturationRecall questions on what members of a homologous series share, functional groups, aliphatic, alicyclic and aromatic compounds, and saturated against unsaturated.Open →
- Structural isomers, bond fission and curly arrowsRecall questions on what structural isomers are, homolytic and heterolytic fission, how radicals are written, and what a curly arrow represents.Open →
- Chain, position and functional group isomerismRecall questions on the three kinds of structural isomerism, with butane and methylpropane, butan-1-ol and butan-2-ol, and propanal and propanone as the worked cases.Open →
- Curly arrows, homolytic and heterolytic fissionRecall questions on where the tail and head of a curly arrow sit, how many electrons a full and a half arrow move, and the species each type of fission produces.Open →
- Nucleophiles, electrophiles, radicals and the mechanism stepsRecall questions on the definitions of nucleophile, electrophile, radical, carbocation and leaving group, and on the initiation, propagation and termination steps.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What does each vertex represent in a skeletal formula, where are the hydrogens, and how do cyclohexane and benzene differ?
Numbers
When is a skeletal formula better than a displayed one, and how are substituents and locants shown in an IUPAC name?
Key term
After identifying the longest carbon chain, how should the carbon atoms be numbered?
Numbers
What do all members of a homologous series share, what is a functional group, and what is the general formula for an alkyl group?
Numbers
What is an alicyclic compound, what carbon–carbon bonds does a saturated compound contain, and which double bond makes a compound unsaturated?
Numbers
Why is a benzene ring classed as unsaturated, what does R represent, and what are structural isomers?
Process
Why is a dot not required when representing oxygen in mechanisms, even though it has unpaired electrons?
Numbers
Butan-1-ol and butan-2-ol both have the formula C₄H₁₀O and contain a hydroxyl group. What type of isomerism is this?
Key term
What does a half curly arrow represent, and what species come from homolytic and heterolytic fission?
Process
How does a nucleophile's attack differ from an electrophile's, and what are an electrophile and a radical?
Process
What happens in nucleophilic substitution, in electrophilic addition, and in the initiation step of radical substitution?
Process
What happens in termination steps of a radical substitution mechanism?
Take Basic Concepts of Organic Chemistry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Structural formula vs Displayed formula
Structural formula: representation showing the arrangement of atoms without every bond. Displayed formula: representation showing every atom and every bond.
Chain isomerism vs Position isomerism
Chain isomerism: same molecular formula with different carbon skeletons. Position isomerism: same skeleton and functional group at different locations.
Electrophile vs Nucleophile
Electrophile: an electron-pair acceptor attracted to electron-rich regions. Nucleophile: an electron-pair donor attracted to electron-deficient regions.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the purpose of IUPAC rules of nomenclature for organic compounds?
Model answer
They provide a systematic method for naming organic compounds to avoid ambiguity.
- 2
When naming an organic compound using IUPAC rules, what is the first step?
Model answer
Identify the longest continuous carbon chain in the molecule.
- 3
After identifying the longest carbon chain, how should the carbon atoms be numbered?
Model answer
The carbon atoms are numbered sequentially from one end of the chain to the other.
- 4
What principle determines which end of the carbon chain to start numbering from?
Model answer
The chain is numbered so that substituents receive the lowest possible locant numbers.
- 5
How is the final IUPAC name of a branched alkane constructed?
Model answer
The substituent names with their position numbers are combined as prefixes to the parent chain name (the name of the longest carbon chain).
- 6
List the names of the first ten straight-chain alkanes in order.
Model answer
Methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, and decane.
What is inside Levo
Six ways to work the same material.
Basic Concepts of Organic Chemistry revision questions
- What does Basic Concepts of Organic Chemistry cover in OCR A-Level Chemistry?
- 7 subtopics: iupac nomenclature and the alkyl groups, general, structural, displayed and skeletal formulae, homologous series, functional groups and saturation, structural isomers, bond fission and curly arrows, chain, position and functional group isomerism, curly arrows, homolytic and heterolytic fission and nucleophiles, electrophiles, radicals and the mechanism steps. Each one has its own page with questions and model answers.
- How is Basic Concepts of Organic Chemistry organised?
- By the OCR H432 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Basic Concepts of 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.
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