Cambridge IGCSE Chemistry 0620 – Comprehensive Study Notes (Version 2, 2023–2025)

Why Cambridge IGCSE Chemistry 0620?

  • Global qualification for 14–16 year olds; exams in 2023–2025 (June/Nov; India-Mar option).

  • Part of Cambridge Pathway; flexible curriculum design; emphasis on long‑term learning, inquiry and real‑world relevance.

  • International recognition and university progression: accepted by many universities; UK NARIC benchmarks Cambridge IGCSE near GCSE standards.

  • Support for teachers: resources, training, and professional development; School Support Hub with forums, past papers, mark schemes, and exemplar responses.

  • Emphasis on transferable skills: data handling, practical problem‑solving, scientific method; attitudes like accuracy, objectivity, integrity, enquiry, initiative, inventiveness.

  • Core aims include developing confident, responsible, reflective, innovative and engaged learners.

Syllabus overview

  • Aims: enable students to

    • acquire scientific knowledge and understanding

    • develop experimental skills (handling variables, safety)

    • use data to solve problems and discuss limitations of methods

    • communicate scientifically with proper terminology, notation, and conventions

    • understand applications’ social, economic and environmental implications

    • enjoy science and develop interest for further study.

  • Content overview: 12 topic areas (states of matter to experimental techniques and chemical analysis).

  • Assessment overview (3 papers total): Core, Extended, and Practical components; AO distribution across papers.

  • Assessment objectives (AOs):

    • AO1: Knowledge with understanding (≈50%)

    • AO2: Handling information and problem‑solving (≈30%)

    • AO3: Experimental skills and investigations (≈20%)

  • Weighting of AOs across components:

    • Papers 1 & 2 (core/extended multiple choice): AO1 63%, AO2 37%

    • Papers 3 & 4: AO1 63%, AO2 37%

    • Papers 5 & 6 (practical): AO3 100%

Subject content (topic by topic)

  • 1 States of matter

    • Core: solids, liquids, gases; properties; particle separation, arrangement, motion; changes of state (melting, boiling, evaporating, freezing, condensing); effects of temperature and pressure on gas volume.

    • Supplement: kinetic particle theory explanations; heating/cooling curves; effects of temperature/pressure on gas volume (supplemental).

  • 2 Atoms, elements and compounds

    • 2.1 Elements, compounds and mixtures (Core); 2.2 Atomic structure and the Periodic Table (Core): nucleus, electrons in shells; proton/atomic number; mass/nucleon number; electronic configuration; group/period trends; noble gas outer shells.

    • 2.3 Isotopes (Core): isotopes have same protons, different neutrons; isotopic symbols; same chemical properties due to electronic configuration; 4 2.4 Ions and ionic bonds (Core): cations/anions; ionic bonds as strong electrostatic attractions; formation and properties of ionic compounds; giant lattice structure.

    • 2.5 Simple molecules and covalent bonds (Core & Supplement): covalent bond as electron pair sharing; examples (H2, Cl2, H2O, CH4, NH3, HCl); properties of simple molecular compounds (low mp/bp, poor electrical conductivity);

    • 2.6 Giant covalent structures (Core): graphite, diamond; uses related to structure; SiO2; Diamond vs SiO2 similarities in properties.

    • 2.7 Metallic bonding (Core/Supplement): metallic bonding as electrostatic attraction between positive ions and delocalised electrons; properties such as electrical conductivity, malleability.

  • 3 Stoichiometry

    • 3.1 Formulae (Core): formulae of elements/compounds; empirical formula basics; constructing word and symbol equations; state symbols.

    • 3.2 Relative masses of atoms and molecules (Core): relative atomic mass Ar; relative molecular mass Mr; relative formula mass (for ionic compounds).

    • 3.3 The mole and Avogadro constant (Core): Avogadro constant $NA = 6.02 \times 10^{23}$; molar relationships $n = \dfrac{m}{M}$; molar gas volume $Vm = 24\ \mathrm{dm^3\,mol^{-1}}$ at r.t.p.; calculating reacting masses, limiting reagents, gas volumes, concentrations; empirical/molecular formula if given data; percentage yield and composition.

  • 4 Electrochemistry

    • 4.1 Electrolysis (Core): definition; identification of anode (+), cathode (−), electrolyte; transfer of charge (electrons in circuit, ions in electrolyte).

    • 4.1 (continued) Products at electrodes for various electrolyses; predicts products for molten salts and aqueous solutions (e.g., CuSO4, NaCl, H2SO4 with inert electrodes). Ionic half‑equations; electrode observations; electroplating.

    • 4.2 Hydrogen–oxygen fuel cells (Core): activity and advantages/disadvantages vs petrol engines.

  • 5 Chemical energetics

    • 5.1 Exothermic and endothermic reactions (Core): temperature changes; enthalpy change $\,\Delta H$; activation energy $E_a$; bond breaking vs bond making; calculating enthalpy change from bond energies.

    • Pathway diagrams: exothermic vs endothermic; enthalpy change and activation energy labeling.

  • 6 Chemical reactions

    • 6.1 Physical and chemical changes (Core & Supplement): distinctions.

    • 6.2 Rate of reaction (Core & Supplement): factors affecting rate: concentration, pressure, surface area, temperature, catalysts (including enzymes); practical rate investigations; collision theory: number of particles, collision frequency, kinetic energy, $Ea$; catalysts lower $Ea$; interpretation of rate data.

    • 6.3 Reversible reactions and equilibrium (Core): reversible symbol ⇌; effect of heat on hydrates; water on hydrated salts; equilibrium in closed systems; forward/reverse rates; condition for equilibrium; Haber process: $N2(g) + 3H2(g) ⇌ 2NH_3(g)$; sources of reactants; typical Haber conditions (450°C, 20000 kPa, iron catalyst).

    • 6.4 Redox (Core): oxidation numbers; redox meaning; strategies to identify oxidising/reducing agents; use of permanganate and iodide tests; half‑equations and ion/electron transfers.

  • 7 Acids, bases and salts

    • 7.1 The characteristic properties of acids and bases (Core): reactions with metals, bases, carbonates; litmus, thymolphthalein, methyl orange indicators; aqueous H+ and OH−; pH concepts; neutralisation: $\mathrm{H^+(aq) + OH^-(aq) → H_2O(l)}$.

    • 7.2 Oxides: acidic vs basic oxides; amphoteric oxides (e.g., Al2O3, ZnO).

    • 7.3 Preparation of salts: acid + alkali, metal, insoluble base or carbonate; solubility rules (e.g., Na+, K+, NH4+; nitrates; chlorides; sulfates; carbonates; hydroxides); hydrated vs anhydrous salts; water of crystallisation.

  • 8 The Periodic Table

    • 8.1 Arrangement: periods and groups; increasing proton number; trends across a period from metallic to non‑metallic; group charges; position predicting properties.

    • 8.2 Group I properties: soft metals; trends down the group (mp, density, reactivity).

    • 8.3 Group VII properties: diatomic non‑metals; trends (density, reactivity); halogen appearances at r.t.p.; displacement reactions.

    • 8.4 Transition elements: properties (high density, high mp, colored compounds, catalytic behavior); variable oxidation numbers.

    • 8.5 Noble gases: unreactive, monatomic; electronic configuration.

  • 9 Metals

    • 9.1 Properties of metals: comparative properties vs non‑metals (thermal/electrical conductivity, malleability, ductility, mp/bp).

    • 9.2 Uses of metals: aluminium and copper examples (low density, conductivity, corrosion resistance).

    • 9.3 Alloys and their properties: brass, stainless steel; why alloys can be harder/stronger; schematic representations and linkages.

    • 9.4 Reactivity series: ordered list K, Na, Ca, Mg, Al, C, Zn, Fe, H, Cu, Ag, Au; reaction behaviour with water, acids; displacement concept; aluminium passivation.

    • 9.5 Corrosion of metals: rusting conditions; barrier methods (painting, greasing, coating); galvanising and sacrificial protection; electron transfer framing.

    • 9.6 Extraction of metals: ore/reactivity position; blast furnace iron extraction steps; carbon sources; slag; bauxite and electrolysis for aluminium; half‑equations for iron extraction; role of cryolite; electrode consumption.

  • 10 Chemistry of the environment

    • 10.1 Water: tests for water presence; purity tests (melting/boiling points); distillation vs tap water; substances in natural water; beneficial vs harmful substances; domestic water treatment steps (sedimentation, filtration, adsorption, chlorination).

    • 10.2 Fertilisers: ammonium salts and nitrates; NPK fertilisers.

    • 10.3 Air quality and climate: composition of dry air; pollutants (CO2, CO, particulates, methane, NOx, SO2); effects (global warming, acid rain, health); greenhouse gases mechanism; strategies to mitigate effects (tree planting, fossil fuel reduction, catalytic converters, flue gas desulfurisation, low‑sulfur fuels).

    • 8–9: Photosynthesis and related processes appear under 10.3 and 11.8.

  • 11 Organic chemistry

    • 11.1 Formulae, functional groups and terminology: display formulae; general formulae for homologous series (alkanes CnH2n+2, alkenes CnH2n, alcohols CnH2n+1OH, carboxylic acids CnH2n+1COOH).

    • 11.2 Naming organic compounds: basic naming from names ending in -ane, -ene, -ol, -oic acid; structural vs displayed formulas; unbranched alkanes, alkenes, alcohols, carboxylic acids; esters from alcohols and carboxylic acids.

    • 11.3 Fuels: fossil fuels (coal, natural gas, petroleum); hydrocarbons; fractional distillation; properties of fractions; uses of each fraction.

    • 11.4 Alkanes: single bonds; saturated; combustion and substitution with chlorine; substitution as photochemical reaction with UV light and formation of monosubstituted products.

    • 11.5 Alkenes: double bonds; cracking to produce alkenes/H2; test for saturation with bromine water; addition reactions.

    • 11.6 Alcohols: fermentation vs steam hydration of ethene; uses and combustion; pros/cons of ethanol production methods.

    • 11.7 Carboxylic acids: reactions with metals, bases, carbonates; formation by oxidation of ethanol; esterification with alcohols.

    • 11.8 Polymers: addition and condensation polymers; repeat units; properties and environmental implications; examples (nylon, PET); basic protein description.

  • 12 Experimental techniques and chemical analysis

    • 12.1 Experimental design: apparatus for time, temperature, mass, volume; evaluation of methods; definitions of solvent, solute, solution, saturated solution, residue, filtrate.

    • 12.2 Acid–base titrations: apparatus, indicator choice, end‑point identification.

    • 12.3 Chromatography: paper chromatography to separate soluble colored substances; interpretation with Rf; locating agents for colorless substances.

    • 12.4 Separation and purification: solvent, filtration, crystallisation, simple and fractional distillation; technique selection.

    • 12.5 Identification of ions and gases: tests for anions (carbonate, chloride, bromide, iodide, nitrate, sulfate, sulfite); tests for cations (Al3+, NH4+, Ca2+, Cr3+, Cu2+, Fe2+, Fe3+, Zn2+); gas tests (NH3, CO2, Cl2, H2, O2, SO2); flame tests for metals; use of a limewater test and other qualitative tests.

Details of the assessment

  • All candidates sit three papers per exam series:

    • Core: Paper 1 (MCQ, Core) and Paper 3 (Theory, Core): 45 min, 40 marks; tests AO1 and AO2; grades C–G.

    • Extended: Paper 2 (MCQ, Extended) and Paper 4 (Theory, Extended): 45 min, 40 marks; tests AO1 and AO2; grades A*–G.

    • Practical: Paper 5 (Practical Test) or Paper 6 (Alternative to Practical): 1 h 15 min, 40 marks (Paper 5) or 1 h 40 min, 40 marks (Paper 6); AO3; externally assessed. Papers 5 and 6 cover the same experimental contexts.

  • Practical assessment focuses on:

    • planning experiments, safety, and technique

    • making and recording observations, measurements and estimates

    • interpreting and evaluating experimental data

    • considering improvements and sources of error.

  • Availability notes: AOs distribution applied across Core/Extended; some papers may be unavailable in certain regions; See syllabus for details.

Apparatus, reagents and safety in the laboratory

  • Comprehensive lists of equipment and reagents are provided (e.g., beakers, burettes, pipettes, gas syringes, flasks, volatile reagents); safety emphasis includes:

    • hazard codes (C for corrosive, MH moderate hazard, HH health hazard, T acutely toxic, F flammable, O oxidising, N hazardous to aquatic environment)

    • appropriate PPE (eye protection) and lab practices; adherence to local regulations (CLEAPSS guidance, COSHH, etc.).

  • Preparedness for practical work:

    • notes for qualitative analysis in papers 5/6

    • detailed lists of reagents and labelled hazard precautions; specific preparation and disposal guidance in confidential exam materials.

Mathematical requirements

  • Calculators permitted; essential skills include:

    • basic arithmetic (add, subtract, multiply, divide)

    • decimals, fractions, percentages, ratios, reciprocals; standard form; rounding rules.

    • algebra: indices, substitutions, solving simple equations

    • geometry/measurements: units, conversions (e.g., cm3 ⇄ dm3, mg ⇄ g, kPa ⇄ Pa)

    • graphs and statistics: drawing/reading graphs, calculating gradient and intercept, interpolation/extrapolation, recognizing proportionality; mean calculation where appropriate.

  • Data presentation: appropriate units, significant figures, properly labeled tables and graphs; use of SI units; careful interpolation and extrapolation.

Presentation of data and conventions

  • Data presentation rules include:

    • accuracy requirements for readings (half‑division interpolation)

    • consistent units and SI units where applicable

    • tables with column headings and units; decimal place conventions; no units in the body of tables

    • adoption of standard graphing conventions (independent on x, dependent on y; clear axes with units; best‑fit line; handling anomalous data)

  • Convention notes include:

    • signs, symbols, and terminology aligned with ASE conventions; both traditional and systematic names may be accepted unless specified otherwise; decimal marker convention (dot)

    • nomenclature and formula naming guidance; use of Roman numerals for oxidation numbers in redox contexts is taught where appropriate

Command words (in assessments)

  • Common command words and their meanings include:

    • Analyse, Calculate, Compare, Consider, Contrast, Deduce, Define, Demonstrate, Describe, Determine, Discuss, Evaluate, Examine, Explain, Give, Identify, Justify, Predict, Show, Sketch, State, Suggest.

  • Use of these words indicates expected depth and type of answer (e.g., Explain requires reasons and relationships; Calculate requires working with given data).

What else you need to know

  • Before you start: guidance on prior learning and recommended guided learning hours (~130 hours per subject); availability and timetables; entry options in June/November (and India: March); combining with other syllabuses; private candidate policies.

  • After the exam: grading and reporting (A* to G; Ungraded); grade descriptions published after first assessment; how grades map to future studies.

  • Group awards (Cambridge ICE): for broader curriculum recognition.

  • Equality and inclusion: measures to avoid bias; access arrangements; language policy (English only).

Changes to this syllabus (for 2023–2025)

  • Version 2 published December 2022; includes updated content summaries (page 55) but no changes to core subject content since Version 2.

  • Notable updates across versions include: inclusion of environmental chemistry topics, hydrogen–oxygen fuel cells, oxidation numbers, plastics, thymolphthalein as an indicator; adjustments to assessment details and data presentation guidelines.

  • Specimen papers and marking schemes accompany changes to specimen assessments; guidance documents provided for exam officers and teachers.

Quick reference: key formulas and concepts

  • Neutralisation: H+(aq)+OH−(aq)→H2O(l)\mathrm{H^+(aq) + OH^-(aq) \rightarrow H_2O(l)}

  • Molar relationship: n=mMn = \dfrac{m}{M}

  • Avogadro constant: NA=6.02×1023N_A = 6.02 \times 10^{23}

  • Molar gas volume (rtp): Vm=24 dm3 mol−1V_m = 24\ \mathrm{dm^3\,mol^{-1}}

  • Reaction enthalpy changes and activation energy: ΔH=enthalpy change of reaction\Delta H = \text{enthalpy change of reaction}; Ea=activation energyE_a = \text{activation energy}

  • Haber process (ammonia synthesis): N<em>2(g)+3H</em>2(g)⇌2NH3(g)\mathrm{N<em>2(g) + 3H</em>2(g) ⇌ 2NH_3(g)}

  • Contact process (sulfuric acid production): 2SO<em>2(g)+O</em>2(g)⇌2SO3(g)\mathrm{2SO<em>2(g) + O</em>2(g) ⇌ 2SO_3(g)}

  • Redox definitions: oxidation number changes, oxidising/reducing agents, and balanced ionic half‑equations.

  • Organic chemistry basics: homologous series, general formulae, functional groups, and common reaction types (substitution, addition, esterification).

  • Environmental chemistry: photosynthesis and the carbon/hydrogen cycle, role of pollutants, and catalytic/sulfur dioxide controls.

Notes on structure for exam preparation

  • Use this as a replacement for the original source by focusing on:

    • Core concepts across all 12 subject content areas

    • Practical skills and data interpretation (AO3)

    • Common examination tasks (papers 1–6) and typical question types

    • Formulae, equations, and units as outlined above

  • For deeper understanding, connect topics to real‑world applications (industrial processes, environmental impact, safety and ethics in chemistry labs).

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