Cambrıdge IGCSE Chemıstry · 0620 / 0971 · Complete Guıde
IGCSE Chemistry
Exam Guide.
Papers, Tips & A*.
IGCSE Chemistry Exam Guide: Everything you need to crack the IGCSE Chemistry exam — from Paper 1 MCQ strategy to Paper 6 practical skills, command words decoded, and the A* action plan that actually works.
IGCSE Chemistry Exam Guide: IGCSE Chemistry Papers — At a Glance
Cambridge IGCSE Chemistry (0620) is assessed through three papers. You sit either the Core or Extended versions of Papers 1 and 3 (or 2 and 4), plus Paper 5 or Paper 6 for practical skills.
💡 Extended vs Core: If you are targeting top universities, Medicine, Engineering or A-Level Chemistry, Extended (Papers 2 + 4) is strongly recommended. Extended unlocks A* and builds the foundation that A-Level requires. Core has a hard ceiling of C — not a performance issue, a structural one. Full Core vs Extended guide →
Paper-by-Paper — What Examiners Actually Reward
Each paper tests different skills. Preparing generically wastes time. Here's what matters most for each paper.
📋 What Paper 2 tests
🎯 How to score full marks
📋 What Paper 4 tests
🎯 How to score full marks
📋 What Paper 6 tests
🎯 How to score full marks
Command Words Decoded — Click Each to Expand
This is one of the most valuable sections in this guide. Students who use the wrong answer style for a command word lose marks even when their chemistry knowledge is correct. Tap each word to see exactly what's expected.
High-Yield Topics — Where Marks Are Won and Lost
Based on past paper analysis across multiple sittings, these topics appear most consistently and carry the most marks. Master these first.
Appears in MCQ, theory calculations and multi-step problems. Mole calculations, percentage yield, limiting reagent — all linked. One weak link cascades into lost marks throughout the paper.
→ Practise step-by-step with past paper questions — not textbook examples only
Combustion, substitution of alkanes (photochemical, UV light), addition reactions of alkenes (bromine, hydrogen, steam). Cracking and the test for unsaturation with bromine water are examined regularly. Displayed formulae and naming up to C4 are required.
→ Know the difference between substitution (alkanes) and addition (alkenes) — examiners test this directly
Calculating enthalpy change using bond breaking and bond making energies is a core Supplement skill. Sign convention matters: bond breaking is endothermic (+), bond making is exothermic (−). Reaction pathway diagrams with activation energy (Ea) are also assessed.
→ Always set out the calculation clearly: bonds broken − bonds formed = ΔH
Le Chatelier's principle questions are predictable — but students lose marks by not distinguishing between rate and equilibrium position. Temperature affects both; concentration only affects position. Haber and Contact process conditions must be justified, not just stated.
→ "Explain why these conditions are used" = rate + equilibrium + economics
Products at cathode and anode, selective discharge for aqueous solutions, ionic half-equations (Supplement). Know the difference between molten and aqueous electrolysis — products differ. Electroplating is also assessed.
→ Aqueous vs molten electrolytes give different products — know both
Titration calculations are pure marks — the method is always the same. Supplement: strong vs weak acid distinction (complete vs partial dissociation), proton donor/acceptor definitions, and amphoteric oxides. Salt preparation methods appear every year.
→ Know all four methods of preparing soluble salts and which acid/base to use
Electronic configuration, dot-and-cross diagrams for ionic and covalent compounds, giant structures (diamond, graphite, silicon dioxide). Metallic bonding (Supplement). Properties must be explained in terms of structure — not just stated.
→ "Explain the properties" always requires linking to bonding and structure
Collision theory questions, effect of concentration/temperature/surface area/pressure/catalyst. A catalyst lowers activation energy — this must be stated explicitly. Supplement: Maxwell-Boltzmann distribution sketches and explaining the effect of temperature on the proportion of particles exceeding Ea.
→ "Explain how a catalyst works" always requires mentioning activation energy
Reactivity series, reactions with water/acid/oxygen, rusting conditions and prevention, blast furnace for iron extraction, electrolysis for aluminium. Sacrificial protection and galvanising (Supplement) require explanation in terms of electron loss and reactivity series.
→ Extraction method depends on position in reactivity series — always link the two
Struggling with any of these topics? We fix that.
From stoichiometry to organic chemistry and electrolysis — every high-yield topic taught with Cambridge past papers and mark scheme language from lesson one.
5-Step A* Action Plan — What Actually Works.
These are the five habits that separate A* students from the rest — not natural talent, just the right approach applied consistently.
Own the Syllabus — It's Your Checklist
The Cambridge syllabus lists every learning objective that can be examined. Print it. Tick off each point only when you can answer a past paper question on it — not when you've read it. This turns passive revision into active accountability.
→ Download the 0620 syllabus from the Cambridge website and use it as a daily tracker
Past Papers — The Only Revision That Matters
Past papers are not just practice — they are the clearest signal of what Cambridge rewards. Do them timed. Mark them honestly using the official mark scheme. Analyse every wrong answer to identify exactly why you lost the mark — was it chemistry knowledge, command word error, or missing mark scheme vocabulary?
→ Improvement happens after the paper, in the review — not during it
Master Command Words Before Anything Else
You can know perfect chemistry and still lose marks if you write an "explanation" when the question said "state." Command word fluency is the fastest single improvement a student can make. See the interactive command words section above.
→ Make flashcards: command word on front, what it requires on the back
Conquer Paper 6 Efficiently
Paper 6 is the most learnable section of the exam. Chemical tests (ions, gases, flame tests) appear every year and can be memorised in one session. Experimental design, graph work and error analysis follow predictable patterns. Scoring 85%+ on Paper 6 is realistic for almost any student who prepares specifically for it.
→ See the standard tests section below — commit them to memory this week
Get Structured Support for Your Weakest Topics
Self-study works for most topics, but some areas — multi-step stoichiometry, bond energy calculations, equilibrium justifications — respond dramatically better to guided teaching. A single session with a tutor who explains the logic (not just the steps) often unlocks what hours of reading cannot.
→ If you've read the same topic three times and it still doesn't click, that's the signal for expert help
Practical Skills — Guaranteed Marks If You Prepare Right.
Paper 6 (Alternative to Practical) is a written exam testing practical reasoning. It has highly predictable question types — and the standard chemical tests appear in almost every sitting.
IGCSE Chemistry Exam — Most Common Questions
Is IGCSE Chemistry hard?
It is demanding but very structured. The syllabus is fixed, the question types are predictable, and past papers give you an accurate picture of what's expected. Students who work consistently with the right method — past papers, mark scheme review, command word awareness — almost always achieve strong grades. Last-minute cramming rarely works because the skills (calculation methods, graph work, practical reasoning) need practice, not memory.
Which paper is the most important?
Paper 4 (Theory — Extended) carries 50% of your final grade and is the highest-stakes paper. However, Paper 2 (MCQ) at 30% is often underestimated as a grade booster. Paper 6 (Alternative to Practical) at 20% is the most learnable paper with the highest return on preparation time. All three matter — but Paper 4 preparation should dominate your revision time.
How many past papers should I do?
Quality beats quantity. Five to ten full past papers — done timed, marked with the official mark scheme, and thoroughly reviewed — is more valuable than twenty papers done casually without review. The review stage (understanding exactly why you lost each mark) is where improvement actually happens. Start with papers from the last 3–4 years, as question styles are most current.
What is the difference between 0620 and 0971?
Cambridge IGCSE Chemistry 0620 is the standard international version, while 0971 is the UK school version. The syllabus content and exam papers are identical — the difference is only in how grades are reported. Students outside the UK sit 0620; the questions, topics, and preparation approach are exactly the same.
Can I resit IGCSE Chemistry to improve my grade?
Yes. Cambridge offers exams in both the May/June and October/November series. Most schools enter students in May/June, but October/November is available for resit candidates. Check with your examination centre for registration deadlines. Note that resitting requires re-entering for the papers you want to improve, not the whole subject automatically.
How can I improve my mark scheme language?
The most effective method is to read mark schemes carefully after every past paper attempt — not just check the final answer, but read the exact wording the mark scheme awards. Identify patterns: which specific words appear for each topic. Over time, your answers will naturally adopt mark scheme vocabulary. A tutor can accelerate this significantly by correcting language in real-time. Book a free diagnostic session →
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