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
Foundations in Chemistry
- 24 subtopics
- 49 things to know
- Components 01, 02 and 03
What Foundations in Chemistry covers
The quantitative and structural groundwork the rest of the course rests on: atomic structure and relative mass, writing formulae and equations, the mole and every calculation that follows from it, acids and titrations, oxidation numbers and redox, and electron configuration.
Where it is assessed
Components 01, 02 and 03
Foundations, drawn on by both long papers and the unified paper.
Check the OCR specification ↗The 24 subtopics
Each one has its own page.
- Atomic structure, isotopes and counting sub-atomic particlesRecall questions on protons, neutrons and electrons, what makes two atoms isotopes, and counting the particles in an atom or an ion from A, Z and the charge.Open →
- Relative isotopic, atomic, molecular and formula massRecall questions on the definitions of relative isotopic and relative atomic mass, the carbon-12 standard, and the weighted-mean calculation from mass spectrometry data.Open →
- Predicting ionic charges and the common ionsRecall questions on deducing an ionic charge from the group, and on the formulae and charges of nitrate, carbonate, sulfate, hydroxide, ammonium, zinc and silver.Open →
- Writing formulae, balanced equations and ionic equationsRecall questions on building an ionic formula from the charges, what a balanced equation requires, state symbols, spectator ions and balancing charge as well as atoms.Open →
- The mole, molar mass and the Avogadro constantRecall questions on amount of substance and its unit, the Avogadro constant, molar mass, and finding an amount from a mass or a number of particles.Open →
- Empirical and molecular formulae, and hydrated saltsRecall questions on finding an empirical formula from percentage composition, scaling it to a molecular formula, and the water of crystallisation in a hydrated salt.Open →
- Gas volumes, concentration and the ideal gas equationRecall questions on molar gas volume at RTP, concentration in mol dm⁻³ and g dm⁻³, and using pV = nRT with SI units throughout.Open →
- Stoichiometry, percentage yield and atom economyRecall questions on the steps of a reacting-mass calculation, theoretical and percentage yield, and calculating atom economy.Open →
- Apparatus, and why high atom economy mattersRecall questions on the apparatus used to measure mass, solution volume and gas volume, and on the waste, resource and cost arguments for high atom economy.Open →
- Mathematical skills and measuring mass, volume and gasRecall questions on standard form, rearranging an equation for an unknown, estimating before calculating, and choosing apparatus of the right precision.Open →
- Acids, alkalis, dissociation and neutralisationRecall questions on the formulae of the common acids and alkalis, strong against weak dissociation, the ionic equation for neutralisation, and the products with carbonates and metal oxides.Open →
- Preparing a standard solutionRecall questions on weighing the solute, transferring it quantitatively to a volumetric flask, making up to the mark and mixing thoroughly.Open →
- Carrying out a titration and its calculationsRecall questions on rinsing and filling the burette, the indicator and the end point, concordant titres, and using the mole ratio to find a concentration.Open →
- Planning an experiment: variables, apparatus and recording resultsRecall questions on independent, dependent and control variables, planning an investigation and choosing apparatus, judging whether a method suits its aim, trial titrations, and recording raw results to the right precision.Open →
- Practical safety, heating and filtrationLaboratory hazards and the precautions for corrosive, irritant, flammable and toxic substances, heating with water baths, sand baths and electric heaters, gravity and reduced-pressure filtration, data loggers, and citing sources.Open →
- Uncertainty, percentage error, precision and accuracyRecall questions on measurement uncertainty for burettes and balances, the uncertainty in a titre, calculating percentage uncertainty and percentage error, accuracy and precision, and random and systematic errors.Open →
- Evaluating results: anomalies, conclusions, limitations and improvementsRecall questions on identifying and excluding anomalous results, drawing and judging conclusions, repeatable and reproducible results, and the limitations and improvements of common experimental procedures.Open →
- Assigning oxidation numbersRecall questions on the rules for elements, monatomic ions, oxygen, hydrogen and fluorine, and on solving for an unknown oxidation number in a compound or ion.Open →
- Roman numerals in names, and the chlorate and nitrate ionsRecall questions on what a Roman numeral tells you, the iron(II) and iron(III) ions, and the formulae of chlorate(I), chlorate(III) and chlorate(V).Open →
- Oxidation, reduction and metals reacting with acidsRecall questions on oxidation and reduction as electron transfer, oxidising and reducing agents, and the products when magnesium, aluminium, iron and zinc react with dilute acids.Open →
- Redox equations and identifying what is oxidisedRecall questions on assigning oxidation numbers across an equation, identifying the species oxidised and reduced, and why the total increase equals the total decrease.Open →
- Shells, orbitals and sub-shellsRecall questions on shell capacities, what an atomic orbital is, the shapes of s and p orbitals, and the number of orbitals and electrons in each sub-shell.Open →
- The order in which sub-shells fillRecall questions on the filling order from 1s to 4p, why 4s fills before 3d, and how electrons occupy orbitals of equal energy.Open →
- Writing electron configurations for atoms and ionsRecall questions on electrons-in-boxes and sub-shell notation, and on writing the configuration of a neutral atom, a cation and an anion.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
How are proton number, electron number and ionic charge related, and how is the neutron count found from A and Z?
Key term
Which isotope is the standard for atomic masses, which technique measures isotopic abundance, and why have atomic models changed?
Numbers
State the formula for calculating relative atomic mass from isotopic data.
Numbers
How is the relative atomic mass of chlorine calculated from isotopic masses 35 (75 %) and 37 (25 %)?
Numbers
Define spectator ions.
Numbers
What is the SI unit of amount of substance, what is molar mass, and what formula gives amount of substance from mass?
Numbers
What amount is in 76.9 g of a substance of molar mass 410 g mol⁻¹, what formula gives the number of particles, and how many particles are in 7.693 mol?
Numbers
What is a molecular formula, how does it relate to the empirical formula, and what is the multiplier when Mr = 345 and the empirical formula mass = 115?
Numbers
How is amount of substance calculated from a gas volume, what is molar gas volume, and how is amount calculated from a solution's concentration and volume?
Numbers
What amount is in 1.987 dm³ of 3.92 mol dm⁻³ solution, what is 3.97 mol dm⁻³ in g dm⁻³ when M = 131 g mol⁻¹, and how is pV = nRT rearranged for n?
Numbers
What amount of gas occupies 0.0045 m³ at 169000 Pa and 233 K (R = 8.315 J K⁻¹ mol⁻¹), and what are the first and last steps of a reacting-mass calculation?
Numbers
How is percentage yield calculated, what is the percentage yield for an actual yield of 79.5 g and a theoretical yield of 80.5 g, and what is theoretical yield?
Key term
What apparatus is used to measure mass with correct precision?
Numbers
What are the chemical formulae of hydrochloric acid, sulfuric acid and nitric acid?
Numbers
What are the chemical formulae of ethanoic acid, sodium hydroxide and potassium hydroxide?
Numbers
What is the ionic equation for neutralisation, and what are the products when an acid reacts with a carbonate or a metal oxide?
Numbers
Why is the burette rinsed with the titrant, how is the titrant added and the end point identified, and what are concordant titres?
Numbers
State the formula used to calculate the number of moles of solute from concentration and volume.
Numbers
Calculate the amount of substance when concentration = 1.81 mol dm⁻³, volume = 0.02 dm³.
Process
Why is a trial titration carried out before the accurate titrations?
Process
In an investigation of how the concentration of hydrochloric acid affects the rate of its reaction with magnesium, what are the independent, dependent and control variables?
Key term
What is the independent variable in an experiment?
Key term
What is the difference between accuracy and precision?
Key term
What is the difference between random and systematic errors?
Process
Calculate the percentage uncertainty in a titre of 24.00 cm³.
Process
Titres of 22.45, 21.90 and 21.95 cm³ are recorded. Which should be used to find the mean titre, and what is the mean?
Evaluation
Give a limitation of starting a gas-producing reaction by adding a solid to acid and then replacing the bung, and suggest an improvement.
Key term
What is the difference between repeatable and reproducible results?
Numbers
Why is fluorine always assigned −1, and how is an unknown oxidation number found in a compound?
Numbers
What are the formulae of chlorate(I), chlorate(III) and chlorate(V), and the oxidation number of chlorine in each?
Process
How are oxidation and reduction defined by electron transfer, and how does the oxidation number change when a species is oxidised?
Key term
What are the products when magnesium, aluminium and iron react with dilute hydrochloric or sulfuric acid?
Numbers
What is the equation for iron reacting with dilute hydrochloric acid, what oxidation state does iron reach, and why does it not reach +3?
Process
What is an atomic orbital, how many electrons can an s-sub-shell hold, and in what order are orbitals filled?
Key term
Which sub-shell is filled after 4s?
Process
When multiple orbitals of equal energy are available, how do electrons fill them?
Numbers
State the ideal gas equation and its quantities.
Numbers
State the atom economy equation.
Numbers
What are the formulae of the carbonate and ammonium ions, and what distinguishes an ionic equation from a full equation?
Numbers
How is atom economy calculated, which apparatus is used to prepare a standard solution accurately, and which mathematical tools are used in composition calculations?
Process
How do high atom economy processes affect production costs?
Process
When preparing a standard solution, how is the mass of solute obtained?
Process
After weighing the solute for a standard solution, what is the next step?
Process
How is the dissolved solute transferred from the beaker to the volumetric flask when preparing a standard solution?
Process
What do the hazard categories corrosive, irritant, flammable and toxic mean, with a laboratory example of each?
Process
When is a water bath used, and when a sand bath?
Numbers
In Fe + 2HCl → FeCl₂ + H₂, which species are oxidised and reduced, what happens to a metal reacting with an acid, and how do you identify what has been reduced in a redox equation?
Numbers
Why does the 4s sub-shell fill before 3d, which sub-shell is filled first, and which is filled immediately after 2s?
Take Foundations in Chemistry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Mass number vs Relative isotopic mass
Mass number: total number of protons and neutrons in a nucleus. Relative isotopic mass: mass of one isotope compared with one twelfth of carbon-12.
Empirical formula vs Molecular formula
Empirical formula: simplest whole-number ratio of atoms of each element. Molecular formula: actual number of atoms of each element in one molecule.
Oxidation vs Reduction
Oxidation: electron loss or an increase in oxidation number. Reduction: electron gain or a decrease in oxidation number.
Questions from this topic
Each one with the model answer underneath.
- 1
What defines isotopes as belonging to the same element?
Model answer
They have the same number of protons (same atomic number).
- 2
How do isotopes of an element differ in their subatomic composition?
Model answer
They have different numbers of neutrons.
- 3
Why do isotopes of the same element have different masses?
Model answer
Because they contain different numbers of neutrons, which contribute to the mass.
- 4
What does the atomic number of an atom represent?
Model answer
The number of protons in the nucleus.
- 5
Define the mass number of an atom.
Model answer
The total number of protons and neutrons in the nucleus.
- 6
In a neutral atom, how does the number of electrons compare to the number of protons?
Model answer
They are equal.
What is inside Levo
Six ways to work the same material.
Foundations in Chemistry revision questions
- What does Foundations in Chemistry cover in OCR A-Level Chemistry?
- 24 subtopics: atomic structure, isotopes and counting sub-atomic particles, relative isotopic, atomic, molecular and formula mass, predicting ionic charges and the common ions, writing formulae, balanced equations and ionic equations, the mole, molar mass and the avogadro constant, empirical and molecular formulae, and hydrated salts, gas volumes, concentration and the ideal gas equation, stoichiometry, percentage yield and atom economy, apparatus, and why high atom economy matters, mathematical skills and measuring mass, volume and gas, acids, alkalis, dissociation and neutralisation, preparing a standard solution, carrying out a titration and its calculations, planning an experiment: variables, apparatus and recording results, practical safety, heating and filtration, uncertainty, percentage error, precision and accuracy, evaluating results: anomalies, conclusions, limitations and improvements, assigning oxidation numbers, roman numerals in names, and the chlorate and nitrate ions, oxidation, reduction and metals reacting with acids, redox equations and identifying what is oxidised, shells, orbitals and sub-shells, the order in which sub-shells fill and writing electron configurations for atoms and ions. Each one has its own page with questions and model answers.
- How is Foundations in Chemistry organised?
- By the OCR H432 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Foundations in Chemistry, on a schedule.
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