Numbers
OCR A-Level Chemistry B H433
Development of Practical Skills in Chemistry
Topic overviewPlanning experimentsImplementing: apparatus, units and recording dataSignificant figures and titration calculationsGraphs, gradients and drawing a conclusionAnomalous results, precision, accuracy and types of errorCalculating uncertainties and improving a methodHazards, risk and control measuresRecording, processing and judging dataMeasuring pH, mass and volume, and choosing an indicatorReflux, distillation, purification and the standard testsPAG1 to PAG6: moles, enthalpy, qualitative analysis and organic synthesisPAG7 to PAG12: electrochemistry, rates and pH
Elements of Life
Topic overviewThe mole, relative masses and empirical formulaeConcentration, titration and writing balanced equationsOrbitals, sub-shells and electron configurationsSub-atomic particles and the evidence for the model of the atomFusion reactions and the origin of the elementsIonic, covalent, dative and metallic bonding and the four structuresMelting point, conductivity and solubility of each structureShapes of molecules and ionsThe periodic table, the blocks and trends in melting pointIon charges, the common polyatomic ions and writing formulaeGroup 2 chemistry and charge densityIonisation enthalpy and trends in reactivitySolubility rules and the tests for the common anionsHydroxide precipitates, ionic equations and identifying an unknown saltAcids, bases and preparing saltsThe electromagnetic spectrum and photon energy calculationsEmission and absorption spectra, and flame testsMass spectrometry and relative atomic mass
Developing Fuels
Topic overviewMolar gas volume and the ideal gas equationGas volume calculations and measuring a gas in the laboratoryBonding and shape in organic moleculesEnthalpy changes: definitions and standard conditionsBond enthalpiesq = mcΔT and measuring an enthalpy change in solutionBurning a fuel, correcting for heat loss, and the assumptions madeHess' law and enthalpy cyclesCatalysts, heterogeneous catalysis and catalyst poisonsCracking and how it is carried outThe pollutants from burning fuels and their effectsCatalytic converters and cutting emissionsAliphatic and aromatic compounds, functional groups and general formulaeDeducing formulae and naming a branched compoundCombustion of organic compoundsAddition of bromine and hydrogen halides, and the test for unsaturationHydrogenation and hydration of alkenesAddition polymerisationElectrophilic addition mechanismDisplayed, shortened and skeletal formulaeChain, position and functional group isomerismWhy alkenes show stereoisomerism, and the E/Z and cis/trans rulesNaming and comparing the stereoisomersSustainable fuels: benefits and risks
Elements From the Sea
Topic overviewAtom economyExtraction of the halogens from sea mineralsElectrolysis of molten salts and writing electrode half-equationsElectrolysis of aqueous solutions and the electrolysis of brineRedox as electron transferThe rules for assigning oxidation statesOxidation state calculations, and defining oxidation and reductionBalancing a redox equation with oxidation statesThe iodine-thiosulfate titration and its calculationsSystematic nomenclature of inorganic compoundsPhysical properties of the halogensHalogen reactivity and the displacement equationsObserving a displacement, and using an organic solvent or starchSilver halide precipitation and testsPreparation of the hydrogen halidesProperties of the hydrogen halidesChlorine: risks, benefits and usesDynamic equilibriumWriting a Kc expression and calculating KcWhat the magnitude of Kc tells you, and what changes itUsing the Kc expression to explain a shift in positionTemperature, pressure and catalysts on an equilibrium
The Ozone Story
Topic overviewElectronegativity and bond polarityIntermolecular bondsBoiling points and intermolecular bondsActivation enthalpy and enthalpy profilesCollision theory and the Boltzmann distributionFollowing a reaction and finding the rate from a graphCatalysts and alternative reaction routesHomogeneous catalysis and intermediatesComposition of gas mixtures by volumeRecognising and naming haloalkanesPrimary, secondary and tertiary haloalkanes, and the aminesProperties and nucleophilic substitution of haloalkanesSubstitution, nucleophiles and the SN2 mechanismRelative reactivity of the haloalkanesHomolytic and heterolytic fission, radicals and half curly arrowsInitiation, propagation and termination in a radical chain reactionOzone depletion by haloalkanesOzone in the stratosphere and troposphereRadiation of the Earth and the SunEffects of UV and visible radiation on moleculesCalculations with frequency, wavelength and energy
What's in a Medicine?
Topic overviewFormulae of oxygen-containing homologous seriesPrimary, secondary and tertiary alcoholsThe acidity of phenol compared with alcohols and carboxylic acidsThe iron(III) chloride test and esterifying a phenolEsterification and oxidising primary, secondary and tertiary alcoholsDehydration, halogenation and planning a two-step synthesisPreparing aspirin, filtering under reduced pressure and recrystallisationThin layer chromatography, Rf values and percentage yieldReflux and distillation in an organic preparationWashing, drying and redistilling a liquid productThe aims of green chemistry and atom economyCatalysts, renewable feedstocks and measuring greennessElimination reactionsThe molecular ion and fragment ionsIdentifying a compound from its fragments and the M+1 peakHow infrared absorption works and the characteristic absorptionsReading a spectrum, the fingerprint region and combining techniques
The Chemical Industry
Topic overviewRate equations, order and the rate constantDeducing the units of k and rate calculationsHalf-livesContinuous monitoring, quenching and the initial rates methodReading order from concentration-time and rate-concentration graphsThe Arrhenius equation and what each symbol meansThe ln k against 1/T plot and finding the activation enthalpyRate-determining step and mechanismEffect of conditions on the magnitude of the equilibrium constantEconomic operating conditions for an industrial processWriting a Kc expression and deducing its unitsICE-table calculations and measuring Kc experimentallyChemical reactions in industrial processesNitrogen, ammonia and the ammonium ionOxidation states of nitrogen and the tests for nitrate and ammoniumCosts, benefits and risks of industrial processes
Polymers and Life
Topic overviewAmino acids, the peptide link and hydrolysing a proteinChromatography of amino acids and Rf valuesProtein structureDNA and RNA structureBase pairing and the genetic codeMolecular recognitionEnzyme kineticsCharacteristics of enzyme catalysisAcidity of carboxylic acidsAmino acids as zwitterionsBasicity of aminesNaming acids, acyl chlorides, anhydrides, esters, aldehydes and ketonesDiols, dicarboxylic acids, amines, amides and the nylonsHydrolysis of esters and amidesReactions of acyl chloridesCondensation polymerisationOptical isomerismFurther interpretation of mass spectraChemical shift and equivalent protons in proton NMRThe n + 1 rule, integration and carbon-13 NMRCombined spectroscopic structure determination
Oceans
Topic overviewSolubility in aqueous and non-aqueous solventsLattice, hydration and solution enthalpies and how they relateMeasuring an enthalpy change of solutionCharge density and the size of enthalpy termsEntropy: qualitative treatmentTotal entropy change and the condition for feasibilityThe limiting temperature, and why a feasible reaction may not happenCalculating the entropy change of the systemThe solubility product expression, its units and calculationsPredicting precipitation and the common ion effectBronsted-Lowry theory of acids and basesStrong acids and strong basesWeak acids, Ka and pKapH of strong acids and strong basespH of weak acids, dilution and the limits of the approximationWhat a buffer is and how it resists a change in pHBuffer calculations, capacity and the natural buffersHow the greenhouse effect works and which gases cause itWhy a molecule absorbs, concentrations in ppm, and ocean chemistry
Developing Metals
Topic overviewManganate(VII) titrations and their calculationsThiosulfate titrations, recording results and good techniqueShapes of complexes and coordination numberBalancing redox equations involving acid-base reactionsSimple electrochemical cellsAction of an electrochemical cellStandard electrode potentials and calculating E°cellRusting and how it is preventedTransition metals: definition, oxidation states and coloursd-block electron configurations of the atoms and their ionsWhy transition metals show variable oxidation statesLigands and complex ionsCoordinate bonding and what makes a ligandBidentate and multidentate ligands, and finding a complex's formulaReactions of Fe2+, Fe3+ and Cu2+ with hydroxide and ammoniaCatalytic activity of transition metalsOrigin of colour in transition metal complexesColorimetry
Colour by Design
Topic overviewHow dyes attach to fibresStructure of a dye moleculeFats and oilsArenes and delocalisationRepresentations of benzene and enthalpy of hydrogenationTests for the common functional groupsIdentifying a polyfunctional molecule from a set of test resultsHalogenation and nitration of benzene and the electrophiles involvedThe nitration mechanism, sulfonation and the Friedel-Crafts reactionsDiazotisation and why it is done coldCoupling reactions, azo dyes and the route from benzeneOxidising an aldehyde and the three carbonyl testsCyanohydrin formation and its use in synthesisUsing the Data Sheet reactions to plan a routeChoosing between routes on yield and atom economyNucleophilic addition mechanismClassifying organic reactions and unfamiliar mechanismsOrigins of colour in organic moleculesHow gas-liquid chromatography separates a mixtureRetention time, peak area and the limits of the technique
Chemical Literacy
Mathematical Skills in Chemistry
Topic overviewUnits, standard form and the mole in calculationsYield, atom economy and logarithmic quantitiesSignificant figures, means and handling dataSymbols, and rearranging the standard equationsSubstituting into rearranged equationsReading spectra and kinetics graphsGradients, calibration lines and the Arrhenius plotShapes and bond angles from electron pair repulsionChiral centres, E/Z isomerism and optical activity
Elements of Life
- 18 subtopics
- 46 things to know
- Components 01, 02 and 03
What Elements of Life covers
The first Salters storyline, which builds the quantitative and structural foundations: the mole and titration, atomic structure and electron configuration, nuclear fusion and where the elements came from, bonding and structure, the periodic table and Group 2, the tests for the common ions, and atomic spectra.
Where it is assessed
Components 01, 02 and 03
Storyline content, drawn on by all three written papers.
Check the OCR specification ↗The 18 subtopics
Each one has its own page.
- The mole, relative masses and empirical formulaeRecall questions on atomic and mass number, isotopes, the Avogadro constant, relative masses, and finding an empirical and a molecular formula.Open →
- Concentration, titration and writing balanced equationsRecall questions on concentration and dilution, preparing a standard solution, titration technique and uncertainty, and writing balanced and ionic equations.Open →
- Orbitals, sub-shells and electron configurationsRecall questions on the shapes of s and p orbitals, sub-shell capacities, the filling order, and the configurations of atoms and of ions.Open →
- Sub-atomic particles and the evidence for the model of the atomRecall questions on counting protons, neutrons and electrons in an ion, the plum pudding model, the Geiger-Marsden experiment, and the evidence from ionisation enthalpies and spectra.Open →
- Fusion reactions and the origin of the elementsRecall questions on why fusion needs such high temperatures, hydrogen burning, and the nuclear equations that build carbon, oxygen, neon and beyond.Open →
- Ionic, covalent, dative and metallic bonding and the four structuresRecall questions on what holds each type of bond together, dative covalent bonds, dot-and-cross diagrams, and the four structure types.Open →
- Melting point, conductivity and solubility of each structureRecall questions on why each structure melts where it does, which conduct and in which states, why ionic crystals are brittle, and which dissolve in water.Open →
- Shapes of molecules and ionsRecall questions on electron pair repulsion, why lone pairs repel more, and the shapes and bond angles of the common molecules and ions.Open →
- The periodic table, the blocks and trends in melting pointRecall questions on how the table is arranged, what a group and a period share, the s, p and d blocks, and the melting point trend across Periods 2 and 3.Open →
- Ion charges, the common polyatomic ions and writing formulaeRecall questions on deducing an ion's charge from its block, the formulae of the common polyatomic ions, and building a neutral formula.Open →
- Group 2 chemistry and charge densityRecall questions on Group 2 reacting with water, oxygen and acids, the trend in reactivity, and the thermal stability and solubility of the compounds.Open →
- Ionisation enthalpy and trends in reactivityRecall questions on writing an ionisation equation, the trends across a period and down a group, and reading a group from successive ionisation enthalpies.Open →
- Solubility rules and the tests for the common anionsRecall questions on which salts are soluble, and the tests for sulfate, carbonate and the halide ions.Open →
- Hydroxide precipitates, ionic equations and identifying an unknown saltRecall questions on the hydroxide precipitates, writing the ionic equations, and sequencing tests to identify an unknown salt.Open →
- Acids, bases and preparing saltsRecall questions on the definitions of acid, base and alkali, neutralisation, and preparing and crystallising a salt.Open →
- The electromagnetic spectrum and photon energy calculationsRecall questions on the order of the spectrum, the relationships linking speed, frequency, wavelength and photon energy, and calculations with them.Open →
- Emission and absorption spectra, and flame testsRecall questions on how each spectrum arises, why the lines converge, why a spectrum identifies an element, and the flame colours of the common ions.Open →
- Mass spectrometry and relative atomic massRecall questions on what a mass spectrum plots, why abundances sum to 100%, and the weighted mean that gives relative atomic mass.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What is the classical definition of the mole, when is relative molecular mass used rather than relative formula mass, and what is the molecular formula of a compound with empirical formula CH₂O and Mᵣ 180?
Numbers
Why can percentage yield never exceed 100%, what is x when 4.99 g of CuSO₄·xH₂O leaves 3.19 g on heating, and what is the concentration when 25.0 cm³ of 2.00 mol dm⁻³ solution is diluted to 250 cm³?
Numbers
Write the balanced equation, with state symbols, for the complete combustion of propane, C₃H₈.
Evaluation
A burette can be read to ±0.05 cm³. What is the uncertainty in a titre of 25.00 cm³, as an absolute value and as a percentage?
Numbers
What are the full electron configurations of sulfur and iron, and why does the 4s sub-shell fill before 3d?
Numbers
What are the electron configurations of Ca²⁺ and S²⁻, and which groups make up the s- and p-blocks?
Key term
How many protons, neutrons and electrons are in one ⁵⁶Fe³⁺ ion and one ³⁷Cl⁻ ion, and what is the outer sub-shell structure of iodine in Group 7 of Period 5?
Key term
What was done in the Geiger–Marsden experiment, and what was observed?
Numbers
Why does fusion need such a high temperature, and what are the equations for hydrogen burning in a star?
Numbers
What are the nuclear equations for forming carbon-12, oxygen-16 and neon-20 by helium capture?
Numbers
What are the equations for two carbon-12 nuclei fusing, for two silicon-28 nuclei, and for carbon-12 with a proton?
Key term
Why does fusion in a star stop producing energy once iron has been formed?
Numbers
What forces balance in a covalent bond, how are the ions arranged in a giant lattice, and why do covalent networks melt so high?
Key term
When solid iodine turns to vapour, what is being broken?
Key term
Why do simple molecular substances not conduct electricity?
Key term
Why are many ionic compounds soluble in water?
Key term
Which repels more strongly, a lone pair or a bonding pair, how do the three types of electron-pair repulsion rank, and why is BeCl₂ linear?
Key term
What shape is PH₃, and what is its bond angle?
Key term
What shape is a hydrogen sulfide molecule, H₂S?
Key term
How is the periodic table divided into blocks, and why does the melting point rise from sodium to aluminium?
Process
Why does silicon melt highest in Period 3, why is there a sharp fall after it, and how does the block fix an ion's charge?
Numbers
What are the two common iron ions, and what are the formulae of iron(III) sulfate and zinc nitrate?
Numbers
What is the formula of ammonium carbonate?
Numbers
What are the equations for barium with cold water and magnesium with oxygen, and how does reactivity change down the group?
Numbers
What forms when a Group 2 element burns in oxygen, and how does carbonate thermal stability change down the group?
Process
Is sodium carbonate more or less thermally stable than magnesium carbonate, what is seen when a Group 2 carbonate decomposes, and which Group 2 hydroxide is most soluble?
Numbers
What are the equations for the first ionisation of magnesium and of chlorine, and the second ionisation of calcium?
Key term
Why does first ionisation enthalpy rise across a period, why is sulfur's lower than phosphorus's, and which Period 3 element is highest?
Numbers
Would potassium or rubidium have the lower first ionisation enthalpy, and which groups do elements with successive ionisation enthalpies 590, 1150, 4940, 6480 and 1310, 3390, 5320, 7450, 11000, 13300, 71300 belong to?
Key term
Why is calcium more reactive than magnesium?
Key term
Which anion always gives a soluble salt, which sulfates are insoluble, and which carbonates are soluble?
Process
Which hydroxides are soluble, why is nitric acid used in the silver nitrate test, and how do you test for ammonium ions?
Numbers
What is seen when hydroxide is added to iron(III) ions and when iodide is added to a lead(II) salt, and what is the ionic equation for silver chloride forming?
Key term
Why does a precipitate form when two solutions are mixed?
Key term
What are the definitions of an acid, a base and an alkali?
Numbers
Why should a filtrate not be evaporated to dryness, and what do magnesium oxide and calcium oxide give with water?
Numbers
Write the equation for the reaction of magnesium oxide with hydrochloric acid.
Numbers
Write the equation for the reaction of calcium hydroxide with nitric acid.
Numbers
How do infrared, visible and ultraviolet rank for frequency and wavelength, and how is photon energy related to frequency?
Key term
Why do the lines in a series converge at higher frequency?
Key term
Why are atomic spectra made of separate lines rather than a continuous band of colour?
Key term
Why can an atomic spectrum be used to identify an element?
Numbers
What is plotted on the horizontal axis of a mass spectrum, why must isotopic abundances add up to 100%, and how does the calculation change when peak heights are in arbitrary units?
Key term
Why is the relative atomic mass of an element essentially the same whatever the source of the sample?
Numbers
Do ³⁵Cl and ³⁷Cl behave differently in chemical reactions? Explain.
Take Elements of Life further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Mass number vs Relative atomic mass
Mass number: the total number of protons and neutrons in a nucleus. Relative atomic mass: the weighted mean isotopic mass compared with one twelfth of carbon-12.
Empirical formula vs Molecular formula
Empirical formula: the simplest whole-number ratio of the atoms present. Molecular formula: the actual number of atoms of each element in one molecule.
Ionic bonding vs Metallic bonding
Ionic bonding: electrostatic attraction between oppositely charged ions in a lattice. Metallic bonding: attraction between a lattice of cations and delocalised electrons.
Questions from this topic
Each one with the model answer underneath.
- 1
What does the atomic number of an element tell you?
Model answer
It is the number of protons in the nucleus of each atom of that element, and it is what fixes the element's identity and its place in the periodic table.
- 2
Define the mass number of an atom.
Model answer
The mass number is the total number of protons and neutrons in the nucleus of the atom.
- 3
What are isotopes?
Model answer
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, so they have the same atomic number but different mass numbers.
- 4
State the value of the Avogadro constant with its unit, and use it to find the number of atoms in 0.500 mol of iron.
Model answer
The Avogadro constant is 6.02 × 10²³ mol⁻¹, so 0.500 mol of iron contains 0.500 × 6.02 × 10²³ = 3.01 × 10²³ atoms.
- 5
Define relative isotopic mass.
Model answer
It is the mass of one atom of a particular isotope compared with one twelfth of the mass of one atom of carbon-12.
- 6
Define relative atomic mass.
Model answer
It is the weighted mean mass of an atom of an element, taking account of the abundance of each isotope, compared with one twelfth of the mass of one atom of carbon-12.
What is inside Levo
Six ways to work the same material.
Elements of Life revision questions
- What does Elements of Life cover in OCR A-Level Chemistry B?
- 18 subtopics: the mole, relative masses and empirical formulae, concentration, titration and writing balanced equations, orbitals, sub-shells and electron configurations, sub-atomic particles and the evidence for the model of the atom, fusion reactions and the origin of the elements, ionic, covalent, dative and metallic bonding and the four structures, melting point, conductivity and solubility of each structure, shapes of molecules and ions, the periodic table, the blocks and trends in melting point, ion charges, the common polyatomic ions and writing formulae, group 2 chemistry and charge density, ionisation enthalpy and trends in reactivity, solubility rules and the tests for the common anions, hydroxide precipitates, ionic equations and identifying an unknown salt, acids, bases and preparing salts, the electromagnetic spectrum and photon energy calculations, emission and absorption spectra, and flame tests and mass spectrometry and relative atomic mass. Each one has its own page with questions and model answers.
- How is Elements of Life organised?
- By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Elements of Life, 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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