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Scientific models: what they are and why we use themDeveloping hypotheses from scientific ideasVariables: independent, dependent and controlWriting a clear, testable predictionPlanning a method: accuracy, precision and rangeRisk assessments: hazards, risks and control measuresChoosing apparatus for accuracy (pipettes, burettes, balances)Recording results in tables with headings and unitsDrawing graphs: choosing scales and plotting pointsUsing lines of best fit and interpreting trendsReliability: repeats, means and anomaliesUncertainty: resolution, range and systematic vs random errorEvaluating a method and suggesting improvementsUsing SI units, prefixes and standard formSignificant figures in practical calculationsRequired practical sign-off: what must be recorded and why (Pearson Qualifications)
Memorising common element symbols and simple formulaeWriting formulae for common ionsTurning word equations into symbol equationsBalancing symbol equations step-by-stepState symbols: solid, liquid, gas and aqueousWriting ionic equations from full equationsIdentifying common hazard symbolsMatching hazard symbols to lab precautionsEvaluating risk in a practical method and improving safety (Pearson Qualifications)
How the Dalton model changed with new discoveriesInside the atom: protons, neutrons and electronsRelative charge and relative mass of subatomic particlesWhy atoms have equal numbers of protons and electronsAtomic number and mass numberIsotopes and why they existCalculating protons, neutrons and electrons in atoms and ionsRelative atomic mass from isotope abundance dataMendeleev’s periodic table: evidence and predictionsPeriods and groups: what the table showsMetals vs non-metals from position and structureElectronic configuration for the first 20 elements (shell model)Linking electron configuration to group and periodForming ions by electron transfer (dot-and-cross)Naming ionic compounds: -ide vs -ateWriting ionic formulae from ion chargesIonic lattices and why ionic compounds have high melting pointsWhen ionic substances conduct electricity (solid vs molten vs aqueous)Covalent bonds as shared pairs of electronsDot-and-cross for key molecules (H2, HCl, H2O, CH4, O2, CO2)Intermolecular forces and why simple molecules have low boiling pointsDiamond vs graphite: structure and propertiesGraphene and fullerenes: structure and key propertiesMetals: delocalised electrons and metallic bondingPolymers as long carbon-chain molecules (intro)Limits of models (dot-and-cross, ball-and-stick, 2D/3D)Relative formula mass (Mr) calculationsPercentage by mass calculationsEmpirical formula from reacting massesEmpirical formula from percentage compositionConservation of mass in reactionsReacting masses from balanced equationsConcentration calculations (g/dm³ and mol/dm³)The mole as “amount of substance”Limiting reactants and “excess” in calculations (Pearson Qualifications)
Particle model: solids, liquids and gasesNaming changes of state (melting, boiling, condensing, freezing, sublimation)Explaining changes of state using energy and particle movementUsing data to predict state at given conditions“Pure” in chemistry vs everyday “pure”Pure substances vs mixtures: key differencesMelting point range vs sharp melting point (purity)Simple distillation: when and why it worksFractional distillation: separating liquids with different boiling pointsFiltration: separating insoluble solids from liquidsCrystallisation: making a soluble salt from solutionPaper chromatography: stationary and mobile phaseInterpreting chromatograms for purity and identityCalculating and using Rf valuesCore practical: inks by chromatography and simple distillation (Pearson Qualifications)Choosing the best separation method from substance propertiesMaking water potable: sedimentation, filtration and chlorinationDistillation to make seawater potableWhy water used in analysis must be salt-free (Pearson Qualifications)
Acids and alkalis as H+ and OH– sourcesThe pH scale and what pH 7 meansIndicators: litmus, methyl orange, phenolphthaleinpH and ion concentration (10× rule)Core practical: tracking pH during neutralisation (Ca(OH)2/CaO) (Pearson Qualifications)Concentrated vs dilute (amount of solute)Strong vs weak acids (degree of dissociation)Bases vs alkalis (soluble base)Acids reacting with metals: products and observationsAcids reacting with metal oxides/hydroxides: neutralisation to saltsAcids reacting with carbonates: CO2 productionGas tests: hydrogen (pop) and carbon dioxide (limewater)Neutralisation as acid + baseNeutralisation at particle level: H+ + OH– → H2OMaking soluble salts using an insoluble reactant (excess, filter, crystallise)Making soluble salts using a soluble reactant (titration needed)Core practical: preparing hydrated copper sulfate crystals (water bath) (Pearson Qualifications)Titration method to make a pure dry salt (overview)Solubility rules for common saltsPredicting precipitates from solubility rulesMaking an insoluble salt by precipitation (filter, wash, dry)Electrolytes: ionic compounds molten or in solutionElectrolysis as decomposition using direct currentIon movement to electrodes (anions → anode, cations → cathode)Predicting products: aqueous electrolysis (competition rules)Predicting products: molten ionic compoundsHalf-equations at anode and cathodeOxidation and reduction as electron loss/gainElectrolysis: oxidation at anode, reduction at cathodeCopper purification using electrolysis (copper electrodes)Core practical: electrolysis of CuSO4 with inert vs copper electrodes (Pearson Qualifications)
Reactivity of metals from reactions with water, acids and salt solutionsDisplacement reactions as redox (electron transfer)The reactivity series (including carbon and hydrogen reference points)Metals in ores vs native metals (uncombined elements)Oxidation and reduction in terms of oxygen gain/lossExtraction as reduction of oresCarbon reduction vs electrolysis: choosing a method (cost + reactivity)Iron extraction idea (meaning of “reduction by carbon”)Aluminium extraction by electrolysis (why it’s expensive)Bioleaching and phytoextraction (why they’re alternatives)Corrosion resistance and reactivity series linksRecycling metals: environmental and economic benefitsLife cycle assessment: raw materials → manufacture → use → disposalInterpreting LCA data to make a judgementReversible reactions and the ⇌ symbolDynamic equilibrium: forward rate = reverse rateAmmonia formation as a reversible reaction (Haber overview)Haber process conditions: temperature, pressure, catalyst (Pearson Qualifications)Predicting equilibrium shifts (temperature, pressure, concentration) (Pearson Qualifications)
Transition metals: typical properties (density, mp, coloured compounds, catalysis)Corrosion as oxidation of metalsPreventing rust: exclude oxygen, exclude water, sacrificial protectionElectroplating: why and how it improves appearance/corrosion resistanceAlloys: why mixing metals changes propertiesWhy steel is an alloy (and why pure iron is limited)Linking metal uses to properties (Al, Cu, Au; magnalium, brass)Concentration in mol/dm³: calculating from moles and volumeConverting between g/dm³ and mol/dm³Core practical: acid–alkali titration (apparatus, method, endpoint) (Pearson Qualifications)Titration calculations: finding unknown concentration or volumePercentage yield: actual vs theoreticalWhy yield is usually <100% (incomplete, losses, side reactions)Atom economy: what it means for sustainabilityCalculating atom economy from equationsChoosing pathways using yield, atom economy, rate, equilibrium, by-productsMolar volume at r.t.p. (24 dm³ per mole) and what it meansUsing molar volume in reacting-mass calculationsAvogadro’s law: using mole ratios to compare gas volumesHaber process revisited: equilibrium as a dynamic processConditions affecting rate of reaching equilibrium (T, P, concentration, catalyst)Industry trade-offs: acceptable yield in acceptable timeNPK fertilisers: what the letters mean and why plants need themAmmonia + nitric acid → fertiliser salt (ammonium nitrate concept)Making ammonium sulfate in the lab (small-scale method)Comparing lab vs industrial-scale fertiliser manufactureChemical cells: voltage until a reactant is used upHydrogen–oxygen fuel cells: reactants and productsEvaluating fuel cells for specific uses (pros/cons) (Pearson Qualifications)
Locating group 1, group 7 and group 0 from periodic table positionGroup 1 properties: soft and low melting pointsGroup 1 reactions with water (Li, Na, K): observations and productsGroup 1 reactivity trend down the groupExplaining group 1 trend using electron configurationGroup 7 colours and states (Cl2, Br2, I2)Group 7 physical trends down the groupTest for chlorine gasHalogens reacting with metals to form metal halidesHydrogen halides and acidic solutions (pattern down the group)Halogen displacement reactions with halide ionsUsing displacement to order halogen reactivity (including astatine)Displacement as redox: identifying what’s oxidised and reducedExplaining group 7 reactivity trend using electron configurationWhy noble gases are inert (full outer shell)Uses of noble gases from inertness, low density and non-flammabilityTrends in noble gas physical properties down the group (Pearson Qualifications)
What “rate of reaction” means in real experimentsCore practical: rate using gas volume (marble chips + acid) (Pearson Qualifications)Core practical: rate using disappearing cross (thiosulfate + acid) (Pearson Qualifications)Drawing and interpreting rate graphs (steeper = faster)Calculating rate from gradients and time dataCollision theory: why reactions happenEffect of concentration on rate (collision frequency)Effect of temperature on rate (collision energy and activation energy)Effect of surface area on rate (exposed particles)Catalysts: lowering activation energyEnzymes as biological catalysts (basic idea)Exothermic vs endothermic reactions (energy out vs in)Reaction profiles: reading energy diagramsActivation energy on reaction profilesBond breaking vs bond making and energy changesCalculating overall energy change using bond energiesUsing profiles to compare catalysed vs uncatalysed reactions (Pearson Qualifications)
Hydrocarbons as compounds of only hydrogen and carbonCrude oil as a complex mixture of hydrocarbonsCrude oil as a finite resource and why that mattersFractional distillation of crude oil: how separation worksFractions and their uses (gases, petrol, kerosene, diesel, fuel oil, bitumen)Why fraction properties change with chain length (bp, viscosity, ignition)Homologous series: definition and CH2 patternComplete combustion of hydrocarbons (products + energy)Incomplete combustion: carbon monoxide and sootWhy carbon monoxide is toxicProblems from incomplete combustion in appliancesSulfur impurities and sulfur dioxide formationAcid rain from sulfur dioxide: impactsNitrogen oxides from high-temperature enginesHydrogen vs petrol as a car fuel (advantages and disadvantages)Fossil fuels: petrol/kerosene/diesel from crude oil; methane from natural gasCracking: turning long alkanes into shorter alkanes and alkenesWhy cracking is needed (demand for fuels and feedstock)Earth’s early atmosphere from volcanic gasesEarly atmosphere evidence (little O2, lots CO2, water vapour)Ocean formation by condensation of water vapourCO2 decrease by dissolving in oceansOxygen increase from photosynthesis (primitive plants)Test for oxygen (relights glowing splint)Greenhouse effect: how gases absorb and re-radiate heatEvaluating evidence for human-caused climate change (correlation + uncertainty)Today’s atmosphere compositionImpacts of increased CO2 and methane and possible mitigation (Pearson Qualifications)
Why each ion test must be uniqueFlame tests: identifying Li+, Na+, K+, Ca2+, Cu2+Cation tests with sodium hydroxide: Al3+, Ca2+, Cu2+, Fe2+, Fe3+, NH4+Test for ammonia gasCarbonate test: acid then CO2 confirmationSulfate test: acid then barium chlorideHalide tests: nitric acid then silver nitrate (Cl–, Br–, I–)Core practical: identifying ions in unknown salts (Pearson Qualifications)Using test results to deduce the ions presentInstrumental methods: why they can be faster/more accurateFlame photometry: calibration curve to find concentrationFlame photometry: identifying ions from reference resultsDrawing and naming alkanes (methane, ethane, propane, butane)Why alkanes are saturatedDrawing and naming alkenes (ethene, propene, butenes)Why alkenes are unsaturated and the C=C functional groupAddition reaction: alkene + bromine (structures of reactants/products)Bromine water test for unsaturation (alkenes vs alkanes)Combustion of alkanes and alkenes as oxidationWhat polymers are (repeating units, high Mr)Making poly(ethene) from ethene (addition polymerisation)Other addition polymers: poly(propene), PVC, PTFELinking monomers and polymers (deducing one from the other)Polymer uses linked to properties (PE, PP, PVC, PTFE)Polyesters as condensation polymers (water formed each link)Problems with polymers (landfill persistence, combustion gases, sorting)Evaluating polymer recycling (economic and environmental trade-offs)Natural polymers: DNA, starch and proteins (what they’re made from)Drawing alcohols (methanol, ethanol, propan-1-ol, butan-1-ol)Alcohol functional group and dehydration to alkenesCore practical: comparing heats of combustion of alcohols (Pearson Qualifications)Drawing carboxylic acids (methanoic to butanoic)Carboxylic acid functional group and acidic propertiesOxidising ethanol to ethanoic acid (and extension idea)Using functional groups to predict reactions in a homologous seriesEthanol by fermentation (yeast enzymes)Concentrating ethanol by fractional distillation after fermentationNanoparticles: size compared to atoms and moleculesNanoparticles: surface area to volume ratio and uses (e.g. sunscreens)Nanoparticles: possible risksComparing materials using data (glass/clay ceramics, polymers, composites, metals)Selecting materials for uses based on properties and data (Pearson Qualifications)
