Detailed syllabus comparison, topic-by-topic gap analysis, marking scheme differences, and a complete Sec 3–4 Scheme of Work (SoW) with a 6-Week Bridging Plan.
Systematic term-by-term plan for Secondary 3 G3 Chemistry (Syllabus K324), including practical work and 5-minute Early IGCSE Habits so students build compatible habits from Day 1.
| Term & Weeks | SEC G3 Topic (K324) | Specific Instructional Objectives (SIOs) & Key Concepts | Practical & Lab Work (Paper 3) | Early IGCSE Habit (5-Min Add-On) |
|---|---|---|---|---|
| Term 1 Weeks 1–3 |
1.1 Experimental Design 2.1 Kinetic Particle Theory |
• Select apparatus for measuring time, temperature, mass, and gas volume (burettes, pipettes, measuring cylinders, gas syringes). • Methods of drying (CaO, conc. H2SO4, fused CaCl2) and collecting gases. • Solid, liquid, gas states, interconversions, and diffusion (Mr and temperature effects). |
• Reading meniscus accurately (burette to 0.05 cm3). • Cooling curve of stearic acid / naphthalene. |
• Also explain how temperature and pressure affect gas volume using KPT (IGCSE 1.1.6) and practise interpreting heating/cooling curve plateaus (IGCSE 1.1.5).
|
| Term 1 Weeks 4–6 |
1.2 Methods of Purification & Analysis |
• Separation of mixtures: filtration, crystallisation, evaporation, sublimation, simple/fractional distillation, separating funnel, paper chromatography (Rf values & locating agents). • Deduce purity from fixed m.p. and b.p. |
• Rock salt purification (dissolving, filtration, crystallisation). • Paper chromatography of food dyes and calculating Rf. |
• Teach exact word-for-word definitions of solvent, solute, solution, saturated solution, residue, and filtrate (IGCSE 12.1.3).
|
| Term 1 Weeks 7–10 |
2.2 Atomic Structure 3.1 Ionic Bonding |
• Protons, neutrons, electrons, electronic shells (1–20), nuclide notation 126C, isotopes. • Electron transfer to form cations/anions; dot-and-cross diagrams (NaCl, MgCl2); giant ionic lattice and physical properties (m.p./b.p., electrical conductivity). |
• Testing electrical conductivity of solid vs aqueous ionic compounds. |
• Practise calculating Ar from isotope % abundances (IGCSE 2.3.4).• Emphasise that isotopes have identical chemical properties because they have the same number of electrons / electronic configuration ( IGCSE 2.3.3).
|
| Term 2 Weeks 11–13 |
3.2 Covalent Bonding 3.3 Metallic Bonding 3.4 Structure & Properties |
• Electron sharing (H2, O2, H2O, CH4, CO2, etc.); simple molecular vs giant covalent structures (diamond, graphite, SiO2). • Metallic lattice (positive ions in a sea of delocalised electrons); pure metals vs alloys (brass, stainless steel). |
• Comparing physical properties (hardness, m.p., conductivity) of unknown samples to deduce bonding/structure. |
• Show the 3D tetrahedral diagram of silicon(IV) oxide (SiO2) and compare its properties directly with diamond (IGCSE 2.6.3–4).• Pair ductility with malleability for metals ( IGCSE 2.7.2).
|
| Term 2 Weeks 14–20 |
4.1 Formulae & Equations 4.2 The Mole Concept & Stoichiometry |
• Balanced chemical and ionic equations with state symbols. • Ar, Mr, Avogadro constant (6.02 × 1023), % composition by mass, empirical & molecular formulae. • Reacting masses, molar gas volume (24 dm3 at r.t.p.), limiting reactants, solution concentration (mol/dm3 & g/dm3), volumetric titration calculations, % yield & % purity. |
• Finding empirical formula of MgO by combustion in a crucible. • Acid-alkali titration using methyl orange and thymolphthalein (two titres within 0.20 cm3). |
• Drill direct calculation of number of particles (N = n × 6.02 × 1023, IGCSE 3.3.3(e)) and word-for-word definitions of empirical vs molecular formula (IGCSE 3.1.2, 3.1.5).
|
| Term 3 Weeks 21–26 |
5.1 Acids & Bases 5.2 Preparation of Salts |
• Strong vs weak acids (extent of ionisation); pH scale & Universal Indicator; reactions of acids with metals, bases, carbonates; reactions of bases with acids and ammonium salts. • Classification of oxides: acidic, basic, amphoteric (Al2O3, ZnO), neutral. • Solubility rules and 3 salt preparation methods: (1) acid + excess metal/insoluble base/carbonate, (2) titration, (3) precipitation. |
• Preparing hydrated CuSO4 crystals (excess CuO + dilute H2SO4). • Preparing PbSO4 / BaSO4 by precipitation. |
• Teach acids as proton (H+) donors and bases as proton (H+) acceptors (IGCSE 7.1.9).• Memorise colour changes of litmus, methyl orange, and thymolphthalein for Theory papers ( IGCSE 7.1.2).
|
| Term 3 Weeks 27–30 |
6. Qualitative Analysis |
• Identification of 7 cations (Al3+, NH4+, Ca2+, Cu2+, Fe2+, Fe3+, Zn2+) using NaOH(aq) and NH3(aq). • Identification of 5 anions (CO32−, Cl−, I−, NO3−, SO42−) and 6 gases (NH3, CO2, Cl2, H2, O2, SO2). |
• Full unknown salt QA practical exercises (recording dropwise vs excess observations and gas tests). | • Flag that IGCSE Paper 5 adds Cr3+, Br−, SO32− and 6 Flame Tests (covered in Bridging Week 5). |
| Term 4 Weeks 31–36 |
8.1–8.3 Periodic Table 8.4 Reactivity Series & Corrosion |
• Periodic trends across a period and down Groups 1, 17, and 18; properties of transition elements. • Reactivity series of metals (reactions with water, steam, dilute HCl; reduction of oxides with C and H2; metal displacement; thermal stability of carbonates). • Rusting conditions and prevention (barrier methods, galvanising, sacrificial protection). |
• Halogen displacement test-tube reactions. • Metal displacement & exothermic temperature rise experiments. |
• Show both Group 1–18 and Group I–VIII labels.• Explain why Aluminium appears unreactive due to its protective Al2O3 layer ( IGCSE 9.4.5).
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Completes the remaining SEC G3 topics (Redox, Electrolysis, Energetics, Rates, Organic Chemistry, and Air Quality) and prepares students for the SEC G3 Examination.
| Term & Weeks | SEC G3 Topic (K324) | Specific Instructional Objectives (SIOs) & Key Concepts | Practical & Lab Work (Paper 3) | Early IGCSE Habit (5-Min Add-On) |
|---|---|---|---|---|
| Term 1 Weeks 1–3 |
7.1 Oxidation & Reduction (Redox) |
• Define redox by oxygen gain/loss, hydrogen gain/loss, electron transfer, and changes in oxidation state. • Testing for oxidising agents using KI(aq) and reducing agents using acidified KMnO4(aq). |
• Redox test-tube reactions with KI(aq) and acidified KMnO4(aq). |
• Teach the 4 explicit oxidation number rules (IGCSE 6.4.9) and remind students not to use hydrogen gain/loss in IGCSE exams.
|
| Term 1 Weeks 4–7 |
7.2 Electrochemistry |
• Electrolysis of molten binary compounds (NaCl) and aqueous solutions (dilute vs conc. NaCl, dilute H2SO4, CuSO4(aq) with inert vs active Cu electrodes). • Ionic half-equations at anode and cathode; electroplating; simple cells; H2–O2 fuel cells. |
• Electrolysis of CuSO4(aq) using carbon vs copper electrodes; copper electroplating. |
• Include molten lead(II) bromide (PbBr2) observations (IGCSE 4.1.3(a)) and pros/cons of H2 fuel cells vs petrol engines (IGCSE 4.2.2).
|
| Term 1 Weeks 8–10 |
9. Chemical Energetics |
• Exothermic (ΔH < 0) and endothermic (ΔH > 0) reactions. • Energy profile diagrams showing ΔH and activation energy (Ea). • Endothermic bond breaking vs exothermic bond making. |
• Enthalpy change of neutralisation / displacement in a polystyrene cup calorimeter. |
• Teach numerical bond energy calculations (ΔH = Σbroken − Σformed, IGCSE 5.1.8) alongside qualitative explanations.
|
| Term 2 Weeks 11–14 |
10. Rate of Reactions 5.3 Ammonia |
• Effects of concentration, pressure, particle size, temperature, and catalysts/enzymes on reaction rate using collision theory. • Reversible reactions (⇌) and interpreting Haber Process industrial data. |
• Rate of reaction labs: (1) gas collection with CaCO3 + HCl, (2) mass loss on balance, (3) sodium thiosulfate disappearing cross, (4) planning (Skill P). |
• Practise drawing tangents to curved rate graphs to calculate gradients (IGCSE Math Req p. 50).
|
| Term 2 Weeks 15–19 |
11.1–11.3 Organic Chemistry (Fuels, Hydrocarbons, Alcohols, Acids & Esters) |
• Fractional distillation of crude oil; biofuels (bioethanol sustainability). • Homologous series, functional groups, isomerism (C1–C4). • Alkanes (combustion, chlorine substitution); Alkenes (cracking, combustion, addition of Br2, H2, H2O(g), margarine hydrogenation). • Alcohols (hydration of ethene vs fermentation, combustion, oxidation to carboxylic acids); Carboxylic acids (weak acid reactions, esterification). |
• Testing saturation using aqueous bromine. • Oxidation of ethanol with acidified KMnO4 and test-tube reactions of ethanoic acid. |
• Use numbered names (but-1-ene, but-2-ene, propan-1-ol, propan-2-ol, IGCSE 11.2.3) and note the exact IGCSE temperatures/pressures (300 °C, 60 atm; 25–35 °C).
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| Term 3 Weeks 20–22 |
11.4 Polymers |
• Addition polymerisation (poly(ethene), deducing repeat units and monomers). • Condensation polymerisation (nylon polyamide and Terylene polyester structures). • Non-biodegradable plastic pollution, physical vs chemical recycling (depolymerisation/acid hydrolysis and cracking). |
• Polymer structure deduction and Past Paper Data-Based Questions on polymer recycling. |
• Note that IGCSE calls Terylene PET (11.8.10(b)) and adds Proteins from amino acids (taught in Bridging Week 4).
|
| Term 3 Weeks 23–28 |
12. Maintaining Air Quality & SEC Prelim / Exam Prep |
• Composition of dry air; sources and effects of CO, CH4, NOx, O3, SO2, unburned hydrocarbons. • Catalytic converters, flue gas desulfurisation (CaCO3), ozone depletion by CFCs, carbon cycle & greenhouse effect. • Full SEC G3 Paper 1, Paper 2, and Paper 3 Prelim & Timed Practice. |
• Full 1 h 50 min Paper 3 Mock Practical Exam (Titration + QA + Skill P Planning). |
• Note that IGCSE specifies calcium oxide (CaO) for flue gas desulfurisation (10.3.4(b)).
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Delivered after completing the SEC G3 syllabus to systematically teach all IGCSE-only topics, new Paper 5 practical tests, and IGCSE marking scheme requirements.
| Bridging Week | IGCSE 0620 Topics Covered | Specific Instructional Objectives (SIOs) & New Content | Teaching Activities, Lab Work & Exam Practice |
|---|---|---|---|
| Week 1 (4–5 hrs) |
• Bond Energy Calculations (5.1.8)• Reversible Reactions & Le Chatelier's Principle ( 6.3.2–4)• Haber & Contact Processes ( 6.3.5–11)
|
1. Calculate Ar from isotopic abundances (2.3.4) and calculate numerical ΔH using Σ(bonds broken) − Σ(bonds formed) (5.1.8).2. Describe reversible hydration/dehydration of CuSO4·5H2O and CoCl2·6H2O ( 6.3.2).3. Define dynamic equilibrium ( 6.3.3) and predict how T, P, concentration, and catalysts shift the position of equilibrium (6.3.4).4. State equations, sources, and exact conditions for the Haber Process (450 °C, 20 000 kPa / 200 atm, Fe; H2 from methane) and Contact Process (2SO2 + O2 ⇌ 2SO3; 450 °C, 200 kPa / 2 atm, V2O5). |
• Lab Demo: Dehydrating blue CuSO4·5H2O crystals and rehydrating with water. • Graphic Organiser: Side-by-side comparison table of Haber vs Contact Process conditions and rate/yield trade-offs. • Topical Drill: IGCSE Paper 4 structured questions on equilibrium shifts and bond energy tables. |
| Week 2 (4–5 hrs) |
• Extraction of Iron in the Blast Furnace (9.6.2, 9.6.4)• Extraction of Aluminium from Bauxite ( 9.6.3, 9.6.5)• Metal Uses & H2 Fuel Cells ( 9.2, 4.2.2)
|
1. Write all 5 Blast Furnace equations (C + O2 → CO2; C + CO2 → 2CO; Fe2O3 + 3CO → 2Fe + 3CO2; CaCO3 → CaO + CO2; CaO + SiO2 → CaSiO3 slag). 2. Explain the extraction of aluminium from purified bauxite (Al2O3): role of cryolite, cathode (Al3+ + 3e− → Al), anode (2O2− → O2 + 4e−), and why carbon anodes must be regularly replaced (C + O2 → CO2). 3. State uses of Al (aircraft, overhead cables, food containers) and Cu (wiring) ( 9.2.1) and compare H2–O2 fuel cells with petrol engines in cars (4.2.2).
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• Diagram Annotation: Labelling the Blast Furnace and Hall–Héroult electrolytic cell. • Equation Drill: Writing ionic half-equations for molten PbBr2 and Al2O3. • Topical Drill: IGCSE Paper 4 questions on metallurgy and proton donor/acceptor reactions. |
| Week 3 (4–5 hrs) |
• Water & Domestic Water Treatment (10.1)• NPK Fertilisers ( 10.2)• Air Quality & Greenhouse Mechanism ( 10.3)
|
1. Describe chemical tests for water (CoCl2 blue → pink; CuSO4 white → blue) and explain why distilled water is used in labs (fewer chemical impurities). 2. Classify substances in natural water as beneficial (dissolved O2, essential metal minerals) or harmful (toxic metals, plastics, sewage microbes, nitrates/phosphates causing deoxygenation). 3. Describe domestic water treatment: (a) sedimentation & filtration, (b) carbon for tastes/odours, (c) chlorination to kill microbes. 4. Describe NPK fertilisers ( 10.2), particulates causing cancer/respiratory issues, greenhouse thermal absorption/emission (10.3.7), FGD using CaO, and the photosynthesis symbol equation (6CO2 + 6H2O → C6H12O6 + 6O2).
|
• Flowchart Activity: Tracing natural river water through sedimentation, filtration, carbon treatment, and chlorination. • Topical Drill: Past IGCSE Paper 4 questions on water purity, NPK fertilisers, and greenhouse gases. |
| Week 4 (4–5 hrs) |
• 8 Petroleum Fractions (11.3)• Numbered Isomers & Exact Organic Conditions ( 11.2, 11.4–11.7)• PET & Proteins from Amino Acids ( 11.8)
|
1. Name all 8 IGCSE petroleum fractions and their uses from top to bottom (refinery gas, gasoline/petrol, naphtha, kerosene/paraffin, diesel oil/gas oil, fuel oil, lubricating oil, bitumen). 2. Name and draw numbered isomers: but-1-ene, but-2-ene, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol ( 11.2.3).3. Quote exact IGCSE conditions: UV photochemical alkane substitution ( 11.4.4); Ni catalyst for alkene hydrogenation; fermentation (25–35 °C, yeast, no O2); ethene hydration (300 °C, 6000 kPa / 60 atm, acid catalyst) and compare both ethanol methods.4. Draw PET and Proteins (natural polyamides formed from amino acid monomers H2N–CH(R)–COOH, 11.8.12–13).
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• Structure Workshop: Drawing amino acid monomers condensing to form protein amide linkages (–CONH–) and comparing them against synthetic Nylon. • Topical Drill: IGCSE Paper 4 organic synthesis and polymer questions. |
| Week 5 (4–5 hrs) |
• IGCSE Paper 5 Practical Skills • Flame Tests & Extra QA Ions ( 12.5)
|
1. Perform and memorise the 6 Flame Tests: Li+ (red), Na+ (yellow), K+ (lilac), Ca2+ (orange-red), Ba2+ (light green), Cu2+ (blue-green). 2. Identify the 3 extra wet QA ions: Cr3+ (green ppt., soluble in excess NaOH, insoluble in excess NH3), Br− (cream ppt. with AgNO3), and SO32− (decolourises acidified KMnO4). 3. Master the 6-mark Paper 5 Planning question format within the 1 h 15 min Paper 5 time limit. |
• Hands-on Lab Session: Flame test station + unknown QA tubes containing Cr3+, Fe2+, Br−, SO32−. • Timed Practical Mock: Full 1 h 15 min IGCSE Paper 5 Practical Exam. |
| Week 6 (4–5 hrs) |
• Marking Scheme Alignment & Full Timed Mock Exams (Papers 2 & 4) |
1. Eliminate all 10 SEC-vs-IGCSE marking scheme mix-ups (see Part 4A checklist below). 2. Build speed for Paper 2 (40 MCQs in 45 min) and Paper 4 (80 marks in 75 min). |
• Timed Mock 1 & 2: Full IGCSE Paper 2 (45 min) + Paper 4 (1 h 15 min) under exam conditions, followed by line-by-line mark scheme review. |
How the exam papers, timings, and question styles compare between Singapore-Cambridge SEC G3 (K324) and Cambridge IGCSE Extended (0620).
| Component | Singapore-Cambridge SEC G3 (K324, 2027) | Cambridge IGCSE Extended (0620, 2026–2028) | What Teachers & Students Need to Note |
|---|---|---|---|
| Level / Stream | G3 Chemistry (equivalent to O-Level Pure Chemistry standard). | Extended Tier (Core + Supplement content, Grades A* to G). | A Sec 4 G3 student already has the conceptual depth needed for IGCSE Extended. |
| Multiple Choice Paper |
Paper 1: 1 h, 40 marks (30% weighting) 40 compulsory questions → 1.5 min per question |
Paper 2 (Extended): 45 min, 40 marks (30% weighting) 40 compulsory questions → ~1.1 min per question |
Time Management: IGCSE gives 15 minutes less for 40 MCQs. Questions are more direct, but students must work faster. |
| Structured & Free Response Paper |
Paper 2: 1 h 45 min, 80 marks (50% weighting) • Section A (70m): Compulsory structured questions, including an 8–12m Data-Based Question. • Section B (10m): Choose 1 out of 2 long questions. |
Paper 4 (Extended): 1 h 15 min, 80 marks (50% weighting) • All compulsory short-answer and structured questions. • No optional section; no long data-based passage. |
Answering Style: IGCSE Paper 4 is 30 minutes shorter for the same 80 marks. Questions are broken into shorter sub-parts that test exact definitions and standard equations. |
| Practical Exam |
Paper 3: 1 h 50 min, 40 marks (20% weighting) • Tests MMO, PDO, ACE (85%) and Planning (15%). |
Paper 5: 1 h 15 min, 40 marks (20% weighting) • Lab practical with 3–4 compulsory questions, ending with a 6-mark Planning question. |
Lab Speed & QA: Paper 5 is 35 minutes shorter. Procedures are more guided step-by-step, and QA includes Flame Tests + Cr3+, Br−, SO32−. |
| Skill Weighting (Theory Papers) |
• Knowledge with Understanding: ~45% (~15% recall) • Application & Problem Solving: ~55% |
• Knowledge with Understanding (AO1): 63% • Application & Problem Solving (AO2): 37% |
Recall vs Application: SEC heavily tests unfamiliar, novel application (55%). IGCSE awards more marks (63%) for accurate recall of standard facts, industrial conditions, and definitions. |
| Periodic Table Group Numbers | Uses Groups 1 to 18 (Group 1, 2, 13–18). | Uses Roman Numerals Groups I to VIII. | Remind students that Group 17 = Group VII and Group 18 = Group VIII. |
Summary of all calculation formulas and must-know chemical equations across SEC G3 and IGCSE Extended.
Example for Chlorine (3517Cl at 75%, 3717Cl at 25%): Ar = [(35 × 75) + (37 × 25)] / 100 = 35.5.
In SEC, students only explain bond breaking/making qualitatively. In IGCSE, students must calculate the exact numerical value of ΔH using a table of bond energies.
Both syllabuses use molar gas volume = 24 dm3 at r.t.p. and Avogadro constant = 6.02 × 1023 mol−1.
Percentage purity = (mass of pure substance / total mass of impure sample) × 100%.
Both forward reactions are exothermic (ΔH < 0); 450 °C is chosen as a compromise between a fast rate of reaction and a reasonable equilibrium yield.
Strong acids (HCl(aq) → H+(aq) + Cl−(aq)) use a single arrow →, while weak acids use the reversible arrow ⇌.
Side-by-side breakdown showing what is covered in SEC G3, what new content must be taught for IGCSE 0620, and key differences in marking requirements.
| Topic | Covered in SEC G3 (K324) | Additional Topics in IGCSE (0620) to Bridge | Watch Out For (Marking & Concept Differences) |
|---|---|---|---|
| 1. Experimental Chemistry & Purification |
• Includes Sublimation (1.2(a)(ii)) and Separating Funnel (1.2(a)(iv)).• Specifies drying agents: CaO, conc. H2SO4, fused CaCl2 ( 1.1(b)).• Importance of purity in foodstuffs & drugs ( 1.2(f)).
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• Exact definitions of solvent, solute, solution, saturated solution, residue, and filtrate (12.1.3).• Explicit formula for Rf ( 12.3.4).
|
Definitions Tested Directly: IGCSE Paper 4 often asks students to define terms like saturated solution ("a solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature"). Sublimation and separating funnels are not tested in IGCSE 12.4.
|
| 2. Kinetic Particle Theory (States of Matter) |
• Solid, liquid, gas interconversion; diffusion in liquids & gases; effect of Mr and temperature on diffusion rate (2.1(a)–(d)).
|
• Effect of temperature & pressure on gas volume explained using KPT (1.1.4, 1.1.6).• Interpreting heating and cooling curves ( 1.1.5).
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Gas Volume vs Pressure: SEC 4.2(f) notes gas volume changes with T and P are not required, while IGCSE 1.1.6 requires students to explain how temperature and pressure affect gas volume using particle motion and spaces.
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| 3. Atomic Structure & Isotopes |
• Protons, neutrons, electrons, electronic shells, nuclide notation 126C, definition of isotopes (2.2(a)–(f)).
|
• Calculate relative atomic mass (Ar) from isotopic masses and abundances (2.3.4).• Explain why isotopes have the same chemical properties ( 2.3.3).
|
Isotope Chemical Properties: Many Sec 3/4 students write "because they are the same element". For IGCSE marks, they must state: "because they have the same number of electrons and therefore the same electronic configuration" (2.3.3).
|
| 4. Chemical Bonding & Structure |
• Ionic, covalent, metallic bonding; simple molecular, macromolecules, and giant covalent structures (3.1–3.4).
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• Describe ionic lattice as a "regular arrangement of alternating positive and negative ions" (2.4.5).• Silicon(IV) oxide (SiO2) structure and how its properties resemble diamond ( 2.6.3–4).• Explain metallic ductility alongside malleability ( 2.7.2(b)).
|
Silicon(IV) Oxide (SiO2) Diagram: SEC mentions sand (SiO2) as an example, but IGCSE expects students to recognise the 3D tetrahedral diagram of SiO2 (each Si bonded to 4 O, each O to 2 Si) and compare it to diamond. |
| Topic | Covered in SEC G3 (K324) | Additional Topics in IGCSE (0620) to Bridge | Watch Out For (Marking & Concept Differences) |
|---|---|---|---|
| 5. Mole Concept & Stoichiometry |
• Full coverage of Ar, Mr, Avogadro constant, molar gas volume (24 dm3), limiting reactants, titrations, % yield, % purity (4.1–4.2).
|
• Word-for-word definitions of molecular formula (3.1.2) and empirical formula (3.1.5).• Calculating exact number of particles using 6.02 × 1023 ( 3.3.3(e)).
|
Very high overlap (~98%). SEC calculation questions are usually harder and less guided than IGCSE Paper 4, where steps are broken down into parts (a), (b), and (c). |
| 6. Electrochemistry & Fuel Cells |
• Simple cells (two different metals in an electrolyte producing voltage) (7.2(j)).• Selective discharge of ions & concentration effects ( 7.2(e)).
|
• Specific observations for molten lead(II) bromide (PbBr2) (4.1.3(a)).• Charge transfer summary: electrons in wires, ions in electrolyte ( 4.1.8).• Pros & cons of H2–O2 fuel cells compared to petrol engines in cars ( 4.2.2).
|
Simple Cells vs Fuel Cells: Simple cells (SEC 7.2(j)) are not in IGCSE. Instead, IGCSE focuses heavily on comparing hydrogen fuel cells with petrol engines for vehicles (4.2.2).
|
| 7. Chemical Energetics |
• Exothermic/endothermic energy profile diagrams, activation energy, and qualitative bond breaking/making explanations (9(a)–(d)).
|
• Numerical Bond Energy Calculations: ΔH = Σ(bonds broken) − Σ(bonds formed) (5.1.8).• Formal definition of Activation Energy (Ea) ( 5.1.5).
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Bond Energy Calculations: SEC only asks students to explain qualitatively why a reaction is exothermic/endothermic in terms of bond breaking and bond making. IGCSE requires full numerical calculations from bond energy tables. |
| 8. Rate of Reaction |
• Effects of concentration, pressure, particle size, temperature, and catalysts/enzymes using collision theory (10(a)–(f)).
|
• Explicit 4-part Collision Theory points (6.2.5): (a) number of particles per unit volume, (b) frequency of collisions, (c) kinetic energy of particles, (d) activation energy Ea.• Evaluating practical methods for rate ( 6.2.8).
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Explaining Temperature Effect: To score full marks in IGCSE, students must mention both more frequent collisions AND a greater proportion of particles having energy ≥ activation energy (Ea). |
| 9. Reversible Reactions & Equilibrium |
• Basic reversible sign ⇌ and reading data tables for the Haber Process (5.3(b)–(c)).• Explicitly states: (knowledge of Le Chatelier's Principle is not required) ( 5.3(c)).• States H2 comes from cracking of crude oil ( 5.3(a)).
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• Reversible heating/hydration of CuSO4 and CoCl2 (6.3.2).• Definition of Dynamic Equilibrium & predicting shifts in equilibrium position (T, P, conc., catalyst) ( 6.3.3–4).• Haber Process: H2 from methane; conditions 450 °C, 20 000 kPa / 200 atm, Fe catalyst ( 6.3.5–7).• Contact Process: 2SO2 + O2 ⇌ 2SO3; sources; conditions 450 °C, 200 kPa / 2 atm, V2O5 catalyst ( 6.3.8–11).
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Major Gap + H2 Source Difference: 1. Le Chatelier's Principle (predicting equilibrium shifts) and the Contact Process are major topics in IGCSE Paper 4. 2. In SEC, H2 for Haber comes from cracking crude oil. In IGCSE, students must write methane ( 6.3.6).
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| 10. Redox Chemistry |
• Defined by oxygen gain/loss, hydrogen gain/loss, electron transfer, and oxidation state (7.1(a)–(c)).
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• 4 explicit rules for working out oxidation numbers (6.4.9).• Formal definitions of oxidising agent and reducing agent ( 6.4.11–12).
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Avoid Hydrogen Gain/Loss in IGCSE: IGCSE 6.4 only defines redox via oxygen, electrons, and oxidation number (not hydrogen gain/loss).
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| Topic | Covered in SEC G3 (K324) | Additional Topics in IGCSE (0620) to Bridge | Watch Out For (Marking & Concept Differences) |
|---|---|---|---|
| 11. Acids, Bases, Oxides & Salts |
• Treating soil acidity with Ca(OH)2 (5.1(f)).• 4 types of oxides: acidic, basic, amphoteric, and neutral ( 5.1(h)).
|
• Define acids as proton (H+) donors and bases as proton (H+) acceptors (7.1.9).• Colour changes of litmus, thymolphthalein, and methyl orange tested in Theory ( 7.1.2, 7.1.5).• Define hydrated, anhydrous, and water of crystallisation ( 7.3.3, 7.3.5).
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Acid/Base Definition: When IGCSE Paper 4 asks to "define an acid/base", students should write proton donor / proton acceptor (not just producing H+/OH− in water). Note IGCSE does not test neutral oxides. |
| 12. Metals: Reactivity, Corrosion & Extraction |
• Reactivity series includes Lead (Pb) (8.4(a)).• Reduction of metal oxides by carbon and/or by hydrogen ( 8.4(a)(ii)).• Thermal decomposition of metal carbonates ( 8.4(d)).
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• Reactivity series includes Aluminium (Al), Carbon, and Gold (Au) (9.4.1).• Why Aluminium appears unreactive (protective oxide layer, 9.4.5).• Uses of Al and Cu linked to properties ( 9.2.1).• Extraction of Iron in the Blast Furnace (all 5 equations & slag formation) ( 9.6.2, 9.6.4).• Extraction of Aluminium from bauxite by electrolysis (role of cryolite, replacing carbon anodes, electrode half-equations) ( 9.6.3, 9.6.5).
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Major Content Gap in SEC K324: The 2027 SEC syllabus removed the Blast Furnace equations and does not cover Aluminium extraction. Both are heavily tested in IGCSE 9.6 and must be taught in full during the bridging weeks.
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| 13. Air, Water & Fertilisers (Environment) |
• Ozone layer depletion by CFCs (12(f)).• Flue gas desulfurisation using calcium carbonate (CaCO3) ( 12(d)(ii)).
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• Water (10.1): Chemical tests for water (CoCl2, CuSO4), purity tests, beneficial vs harmful substances in natural water, domestic water supply treatment (sedimentation/filtration, carbon, chlorination).• NPK Fertilisers ( 10.2): Ammonium salts, nitrates, N, P, K roles.• Particulates → respiratory problems & cancer ( 10.3.3(c)).• How greenhouse gases cause warming ( 10.3.7) & Photosynthesis equations (10.3.6, 10.3.9).• Flue gas desulfurisation using calcium oxide (CaO) ( 10.3.4(b)).
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New Chapters & FGD Reagent: 1. Water ( 10.1) and Fertilisers (10.2) are not in SEC and must be taught fresh.2. In IGCSE, state calcium oxide (CaO) for flue gas desulfurisation. 3. Ozone depletion by CFCs is not in IGCSE (make sure students don't mix up ozone depletion with global warming). |
| 14. Organic Chemistry & Polymers |
• Biofuels (bioethanol from sugarcane) sustainability (11.1(c)–(d)).• Polyunsaturated food & margarine hydrogenation ( 11.2(k)–(l)).• Plastic recycling (physical vs chemical depolymerisation/cracking) & acid hydrolysis of polyesters ( 11.4(h)–(i)).
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• 8 Named Petroleum Fractions & trends down/up the column (chain length, volatility, boiling point, viscosity) (11.3.6–7).• Numbered isomer names: but-1-ene, but-2-ene, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol ( 11.2.3).• Photochemical alkane substitution: UV light provides activation energy Ea ( 11.4.4).• Exact reaction conditions: Ni catalyst (alkene + H2); 25–35 °C (fermentation); 300 °C, 6000 kPa / 60 atm, acid catalyst (ethene + steam) ( 11.5–11.6).• Proteins as natural polyamides from amino acids, plus PET ( 11.8.10–13).
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Memorising Exact Conditions & Isomer Numbers: SEC p. 21 states specific temperature and pressure figures are not required. In IGCSE, students must memorise the exact numbers (300 °C, 6000 kPa / 60 atm and 25–35 °C), use numbered names (butan-1-ol vs butan-2-ol), and draw protein/amino acid structures. |
A handy checklist of questions where an answer taught in Singapore SEC G3 Chemistry will not be accepted by the Cambridge IGCSE 0620 marking scheme.
| Exam Question | ❌ Usual SEC G3 Answer (Not Accepted in IGCSE) | ✅ Required IGCSE 0620 Answer |
|---|---|---|
| "State the source of hydrogen for the Haber process." | "Cracking of crude oil / hydrocarbons" (SEC 5.3(a)) |
"Methane (natural gas) / reaction of methane with steam" (IGCSE 6.3.6) |
| "Define an acid and a base." | "An acid produces H+ ions in water; an alkali produces OH− ions." (SEC 5.1(a)) |
"An acid is a proton (H+) donor; a base is a proton (H+) acceptor." (IGCSE 7.1.9) |
| "State the typical conditions for the Haber process." | Reading off approximate values from a given table (SEC 5.3(c)) |
"450 °C, 20 000 kPa (or 200 atm), and an iron catalyst." (IGCSE 6.3.7) |
| "State the typical conditions for the Contact process." | Not in SEC K324 syllabus | "450 °C, 200 kPa (or 2 atm), and a vanadium(V) oxide (V2O5) catalyst." (IGCSE 6.3.10) |
| "State the conditions for manufacturing ethanol from ethene and steam." | "High temperature and pressure with phosphoric acid catalyst." (SEC 11.3(d)) |
"300 °C, 6000 kPa (or 60 atm), and an acid catalyst." (IGCSE 11.6.1(b)) |
| "State the conditions for fermentation of aqueous glucose." | "Warm temperature with yeast in the absence of air." (SEC 11.3(d)) |
"25–35 °C, in the presence of yeast, and in the absence of oxygen." (IGCSE 11.6.1(a)) |
| "Explain why isotopes have the same chemical properties." | "They are atoms of the same element with the same proton number." | "They have the same number of electrons and therefore the same electronic configuration." (IGCSE 2.3.3) |
| "Name the calcium compound used in flue gas desulfurisation." | "Calcium carbonate (CaCO3)" (SEC 12(d)(ii)) |
"Calcium oxide (CaO)" (IGCSE 10.3.4(b)) |
| "Name the unbranched isomers of C4H8 and C3H7OH." | "Butene" and "Propanol" (SEC 11.2(g), 11.3(b)) |
"but-1-ene and but-2-ene" / "propan-1-ol and propan-2-ol" (IGCSE 11.2.3) |
| "An unknown solution gives a green precipitate with NaOH(aq)..." | Assuming the cation must be Fe2+ (SEC QA Notes) |
Check solubility in excess NaOH(aq): Insoluble in excess = Fe2+; Soluble in excess (giving a green solution) = Cr3+ (IGCSE 12.5.2). |
Extra ions, flame colours, and chemical tests for water tested in IGCSE Paper 5 that are not in the SEC G3 Paper 3 QA Notes.
IGCSE 12.5.4)
| Metal Ion | IGCSE Flame Colour |
|---|---|
| Lithium, Li+ | Red |
| Sodium, Na+ | Yellow |
| Potassium, K+ | Lilac |
| Calcium, Ca2+ | Orange-red |
| Barium, Ba2+ | Light green |
| Copper(II), Cu2+ | Blue-green |
IGCSE 10.1.1, 12.5.1–2)
| Ion / Substance | Test / Reagent | Observation / Result |
|---|---|---|
| Chromium(III), Cr3+ | 1. Add NaOH(aq) 2. Add NH3(aq) |
1. Green ppt., soluble in excess 2. Green ppt., insoluble in excess |
| Bromide, Br− | Acidify with dilute HNO3, then add AgNO3(aq) | Cream ppt. (compare with Cl− white & I− yellow) |
| Sulfite, SO32− | Add a small volume of acidified KMnO4(aq) | Changes colour from purple to colourless |
| Water, H2O | 1. Anhydrous CoCl2 2. Anhydrous CuSO4 |
1. Turns from blue to pink 2. Turns from white to blue |