IGCSE Chemistry Revision Notes (0620): The Complete Topic-by-Topic Guide

If your child is sitting Cambridge IGCSE Chemistry, these IGCSE Chemistry revision notes are built to make the whole course click. Cambridge IGCSE Chemistry 0620 covers 12 big topics, from the particles that make up matter to the organic chemistry of fuels and plastics. That is a lot of ground. This guide walks through every topic in plain English, tells you what really matters for the exam, and shows how the papers fit together. It is the map we wish every student had before they opened a textbook.

We teach this syllabus every week, so we have written these notes the way we explain things to our own students: short sentences, clear facts, and no filler.

Quick answer: what are the IGCSE Chemistry 0620 revision notes you actually need?

Cambridge IGCSE Chemistry (0620) has 12 topics: States of matter, Atoms/elements/compounds, Stoichiometry, Electrochemistry, Chemical energetics, Chemical reactions, Acids/bases/salts, The Periodic Table, Metals, Chemistry of the environment, Organic chemistry, and Experimental techniques and chemical analysis. Every student sits three papers: a multiple-choice paper, a theory paper, and one practical paper. Core students take Papers 1, 3, and 5 or 6 and can earn grades C to G. Extended students take Papers 2, 4, and 5 or 6 and can earn grades A* to G. The best revision covers all 12 topics, then drills exam-style questions on the ones that carry the most marks.

Below, we break down each topic and the exam structure. Skim the section you need, or read the whole thing once for the full picture.

How to use these IGCSE Chemistry revision notes

Use these notes as a checklist first, then as a study guide. Read the topic list and mark the ones that feel shaky. Those are where your revision time should go.

Chemistry rewards little-and-often practice. Twenty minutes a day beats a three-hour cram the night before. Here is a simple loop that works:

• Read one topic's key facts below.

• Close the notes and write down what you remember.

• Check what you missed, then do 3 to 5 past-paper questions on that topic.

• Move to the next topic the next day.

If a topic keeps tripping you up, that is the moment to get help rather than repeat the same mistake. A specialist IGCSE Chemistry tutor can spot the exact gap in an hour that might take weeks to find alone. First, though, let's look at how the exam is built, because that decides what to prioritise.

The IGCSE Chemistry 0620 exam at a glance

Cambridge IGCSE Chemistry 0620 is assessed by three papers, and everyone sits one from each group: a multiple-choice paper, a theory paper, and a practical paper. The paper you take depends on whether you follow the Core route or the Extended route.

Here is the full structure:

The practical group is the same for both routes:

A few things every parent and student should know. Core students can only reach grade C at the top. If your child is aiming for an A or A*, they must sit the Extended papers (2 and 4). The theory paper is worth 50% of the grade, so it is the single most important paper to master. And the practical paper is worth a full 20%, which many students underestimate.

One more useful fact: 0620 (graded A*–G) is the same course as 0971 (graded 9–1). The content, papers, and mark schemes are identical. Only the grade labels differ, depending on which version your school enters you for. For a full breakdown of how grades are set each session, see our guide to IGCSE grade boundaries.

Calculators are allowed in every paper, and you are given a copy of the Periodic Table in the exam. You do not have to memorise it, but you do need to know how to read it.

Now, the 12 topics.

Topic 1: States of matter

States of matter is about how particles behave as solids, liquids, and gases, and what happens when a substance changes state. This is the foundation for everything else in chemistry.

Key facts to lock in:

• Solids have particles packed tightly in a fixed pattern; they vibrate but do not move around.

• Liquids have particles close together but able to slide past each other.

• Gases have particles far apart, moving fast in all directions.

• Changes of state: melting, boiling, evaporating, freezing, and condensing.

• Diffusion is particles spreading out from high to low concentration. Lighter (lower relative molecular mass) gases diffuse faster.

Extended students also explain diffusion using relative molecular mass. Make sure you can describe, not just name, each change of state.

Topic 2: Atoms, elements and compounds

This topic covers what atoms are made of and how they join together to form elements, compounds, and mixtures. It is the language of the whole subject, so a shaky grip here hurts everywhere.

The must-know points:

• Atoms contain protons (positive), neutrons (neutral), and electrons (negative).

• Proton number (atomic number) defines the element. Nucleon number is protons plus neutrons.

• Isotopes are atoms of the same element with different numbers of neutrons.

• Electrons sit in shells. The first holds 2, the next hold 8.

• Bonding: ionic (metal + non-metal, transfer of electrons), covalent (non-metals sharing electrons), and metallic (a lattice of ions in a "sea" of electrons).

Extended students draw dot-and-cross diagrams and explain why giant structures like diamond, graphite, and sodium chloride have their properties. Practice these diagrams until they are automatic.

Topic 3: Stoichiometry

Stoichiometry is the maths of chemistry: formulae, equations, and the mole. It scares students, but it is really just careful counting.

Nail these:

• Write and balance symbol equations. The number of each atom must match on both sides.

• Relative atomic mass (Ar) and relative molecular mass (Mr).

• The mole is a unit for counting particles. Moles = mass ÷ Mr.

• Use ratios in balanced equations to work out reacting masses.

Extended students go further with the Avogadro constant, concentration in mol/dm³, percentage yield, percentage purity, and calculations from gas volumes. Stoichiometry appears across many questions, so time spent here pays off across the whole paper.

Topic 4: Electrochemistry

Electrochemistry is about using electricity to break down compounds, a process called electrolysis. It links to industry, batteries, and metal extraction.

Core ideas:

• Electrolysis splits an ionic compound (molten or in solution) using electricity.

• The cathode is negative and attracts positive ions (cations). The anode is positive and attracts negative ions (anions).

• Learn the products of electrolysing molten lead bromide and concentrated aqueous solutions.

Extended students predict products for a range of solutions, write half-equations, and describe electroplating and the electrolysis of copper using copper electrodes. Hydrogen-oxygen fuel cells also appear here. Half-equations are a common exam trap, so practise them.

Topic 5: Chemical energetics

Chemical energetics is about the energy taken in or given out during reactions. It explains why some reactions warm up and others go cold.

Core points:

• Exothermic reactions release energy to the surroundings; the temperature rises (for example, combustion).

• Endothermic reactions take in energy; the temperature falls.

• Energy-level diagrams show reactants, products, and the energy change.

Extended students use bond energies to calculate the overall energy change of a reaction. The rule: breaking bonds takes in energy, making bonds gives out energy. Get the signs right and these questions are easy marks.

Topic 6: Chemical reactions

This topic covers rates of reaction, reversible reactions, and redox. It is one of the biggest topics, so give it extra time.

Rate of reaction essentials:

• Rate goes up with higher temperature, higher concentration, larger surface area, and a catalyst.

• A catalyst speeds up a reaction without being used up.

• Collision theory explains why: more frequent, more energetic collisions mean a faster rate.

Also in this topic:

• Reversible reactions and the ⇌ symbol.

• Redox: oxidation is loss of electrons, reduction is gain (remember "OIL RIG").

• Oxidising and reducing agents.

Extended students explain equilibrium and how changing conditions shifts it (Le Chatelier's idea), plus oxidation numbers. This topic rewards clear definitions, so learn them word for word.

Topic 7: Acids, bases and salts

This topic is about acids, alkalis, the pH scale, and how to make salts. It is heavy on practical work, so it links straight to Papers 5 and 6.

Core facts:

• Acids have a pH below 7; alkalis have a pH above 7; neutral is 7.

• Acids react with metals, bases, and carbonates in predictable ways.

• Indicators (litmus, thymolphthalein, methyl orange) show acid or alkali.

• Salt preparation: titration, and adding excess solid to an acid then filtering.

Extended students classify oxides as acidic, basic, amphoteric, or neutral, and describe the difference between strong and weak acids. The four salt-preparation methods are a favourite exam question, so know which method suits which salt.

Topic 8: The Periodic Table

The Periodic Table topic explains how elements are arranged and how their properties change across it. You get a copy in the exam, but you must know the patterns.

Learn these groups:

• Group I (alkali metals): soft, reactive, get more reactive down the group.

• Group VII (halogens): coloured non-metals, get less reactive down the group; a more reactive halogen displaces a less reactive one.

• Group VIII (noble gases): unreactive because they have full outer shells.

• Transition elements: hard, dense metals, form coloured compounds, and act as catalysts.

Extended students explain trends using electron shells and predict the properties of unfamiliar elements. Patterns matter more than memorising facts here.

Topic 9: Metals

This topic covers the reactivity series, how metals are extracted, and how we stop them corroding. It connects chemistry to real industry.

Core content:

• The reactivity series ranks metals from most reactive (potassium) to least (gold).

• More reactive metals displace less reactive ones from their compounds.

• Iron is extracted in a blast furnace; reactive metals like aluminium are extracted by electrolysis.

• Rusting needs both oxygen and water. Barrier methods and galvanising prevent it.

Extended students explain sacrificial protection and the properties and uses of alloys such as steel and brass. The reactivity series ties together displacement, extraction, and rusting, so learn it first.

Topic 10: Chemistry of the environment

This topic looks at water, air quality, and the chemistry behind climate and pollution. It is topical and often makes for good higher-mark questions.

Key ideas:

• Test for water using anhydrous copper(II) sulfate (turns blue) or cobalt(II) chloride paper.

• Clean air is roughly 78% nitrogen, 21% oxygen, with small amounts of other gases.

• Common pollutants: carbon dioxide, carbon monoxide, sulfur dioxide, and oxides of nitrogen. Know their sources and effects.

• Greenhouse gases and climate change; catalytic converters reduce harmful car emissions.

Extended students describe how nitrogen oxides form in engines and the role of fertilisers. Facts and figures score well here, so learn the numbers.

Topic 11: Organic chemistry

Organic chemistry is the chemistry of carbon compounds, including fuels, alcohols, and plastics. It has its own naming system, which is worth learning early.

Core essentials:

• Homologous series: alkanes, alkenes, alcohols, and carboxylic acids. Each has a general formula and shared properties.

• Alkanes are saturated (single bonds); alkenes are unsaturated (a C=C double bond).

• Test for alkenes: they decolourise bromine water.

• Fossil fuels, fractional distillation of crude oil, and combustion.

• Ethanol can be made by fermentation.

Extended students draw structural formulae, explain isomerism, describe addition and substitution reactions, and cover polymers (addition and condensation). Naming and drawing structures is where marks are won or lost, so practise both.

Topic 12: Experimental techniques and chemical analysis

This final topic covers measuring, separating, and identifying substances, and it feeds directly into the practical papers. It is the most "hands-on" topic on the course.

Core skills:

• Measure time, temperature, mass, and volume with the right apparatus.

• Separation methods: filtration, crystallisation, distillation, and chromatography.

• Criteria for purity, including melting and boiling points.

• Identify common gases: hydrogen (squeaky pop), oxygen (relights a glowing splint), carbon dioxide (turns limewater milky), ammonia (damp red litmus turns blue), and chlorine (bleaches damp litmus).

Extended students interpret chromatograms with Rf values and carry out ion tests for cations, anions, and gases. These tests come up in almost every practical paper, so make a one-page summary and review it often.

How to revise IGCSE Chemistry the smart way

The best IGCSE Chemistry revision mixes learning the facts with doing past-paper questions, topic by topic. Reading alone does not work for chemistry. You have to practise applying it.

Here is the routine we give our students:

• Split the 12 topics across your weeks. Do not leave organic chemistry or stoichiometry until the end.

• Use active recall. Cover the notes and write out what you remember. Blank pages show you what you do not know.

• Do past papers by topic first, then whole papers. Cambridge past papers with mark schemes are the gold standard.

• Mark your own work using the mark scheme. Learn the exact wording examiners want. Chemistry loves precise definitions.

• Keep a "mistakes book." Every question you get wrong goes in it. Review it weekly.

Chemistry builds on itself. If atoms and bonding (Topic 2) are shaky, then metals, the Periodic Table, and organic chemistry will all feel harder. Fix the foundations first.

If your child studies more than one science, it helps to plan revision across all of them together. Our IGCSE Biology revision notes (0610) follow the same topic-by-topic format, so you can build one clear timetable for both subjects. Chemistry is just one of many IGCSE courses, and our full IGCSE subjects list shows how it sits alongside the rest.

Core or Extended: which should your child take?

Choose Extended if your child is aiming for grades A* to C, and Core if a grade C to G is the realistic and comfortable target. This is one of the most important decisions of the course.

Extended covers everything in Core plus the Supplement content. It reaches the top grades, but it is harder and covers more. Core is a smaller course and caps at grade C. Most students who plan to study science at A Level or IB take Extended.

Schools usually decide the entry, often after mock exams. If you are not sure which route fits your child, that is a good conversation to have with their teacher or tutor early, not in the final term. To see how IGCSE fits into the bigger picture of school qualifications, our guide on what IGCSE is explains the whole system for parents.

Chemistry is a subject where the right support at the right moment changes the grade. If your child is stuck, a free trial with a specialist is the fastest way to find out what would actually help. You can book a trial class and see the difference in one session.

Frequently asked questions about IGCSE Chemistry (0620)

How many topics are in IGCSE Chemistry 0620?

Cambridge IGCSE Chemistry 0620 has 12 topics: States of matter; Atoms, elements and compounds; Stoichiometry; Electrochemistry; Chemical energetics; Chemical reactions; Acids, bases and salts; The Periodic Table; Metals; Chemistry of the environment; Organic chemistry; and Experimental techniques and chemical analysis. Every student is taught the Core content, and Extended students add the Supplement material on top.

How many papers are there in IGCSE Chemistry?

Every student sits three papers. You take one multiple-choice paper, one theory paper, and one practical paper. Core students take Paper 1, Paper 3, and either Paper 5 or Paper 6. Extended students take Paper 2, Paper 4, and either Paper 5 or Paper 6. The theory paper is worth 50% of the grade, the multiple-choice paper 30%, and the practical 20%.

What is the difference between Core and Extended in IGCSE Chemistry?

Core is the smaller course and the highest grade you can earn is a C. Extended includes all the Core content plus extra Supplement content, and it lets you reach grades A* to G. Students aiming for A Level or IB science usually take Extended. Your school normally decides the entry, often based on mock exam results.

Is IGCSE Chemistry 0620 the same as 0971?

Yes. 0620 and 0971 are the same course with the same syllabus, papers, and mark schemes. The only difference is the grading scale. 0620 is graded A* to G, while 0971 is graded 9 to 1. Your school chooses which version to enter you for, usually based on the region.

Do you get a Periodic Table in the IGCSE Chemistry exam?

Yes. A copy of the Periodic Table is provided in every IGCSE Chemistry paper, so you do not need to memorise it. You do, however, need to know how to read it, including how to find relative atomic mass, group, and period. You should also know the properties and trends of Groups I, VII, and VIII.

Can you use a calculator in IGCSE Chemistry?

Yes, calculators are allowed in all IGCSE Chemistry papers, including the multiple-choice and theory papers. This helps with stoichiometry and other calculation questions. Always show your working in structured questions, because you can earn method marks even if the final answer is wrong.

Which IGCSE Chemistry topic is the hardest?

Most students find Stoichiometry (Topic 3) the hardest because it involves the mole and calculations. Organic chemistry (Topic 11) is a close second, mainly because of the naming and structures. The good news is both improve quickly with practice. Doing lots of past-paper questions on these two topics gives the biggest grade boost.

How do I revise for IGCSE Chemistry effectively?

Revise topic by topic, and mix learning facts with doing past-paper questions. Read a topic, close the notes, and write down what you remember. Then do three to five exam-style questions and mark them with the official mark scheme. Keep a "mistakes book" of every question you get wrong and review it every week. Short daily sessions beat long last-minute cramming.

Where can I find IGCSE Chemistry past papers?

Cambridge IGCSE Chemistry past papers and mark schemes are available on the Cambridge International website and through your school's teacher portal. Each pack includes the question paper, mark scheme, and often an examiner report. Practising with the mark scheme open teaches you the exact wording examiners reward, which is one of the fastest ways to raise your marks.

How important is the practical paper in IGCSE Chemistry?

The practical paper is worth 20% of the final grade, so it matters a lot. You take either Paper 5 (a hands-on Practical Test) or Paper 6 (Alternative to Practical, a written paper about experiments). Both test the same skills: measuring, observing, recording, and drawing conclusions. Learning the standard tests for gases and ions gives you reliable marks on this paper.

What grade do I need in IGCSE Chemistry to study it at A Level or IB?

Most schools ask for at least a grade B or 6 in IGCSE Chemistry, and often an A or 7, to move on to A Level or IB Higher Level Chemistry. This usually means taking the Extended papers, since Core caps at a C. If your child is aiming for advanced science, focus on the Extended content and target the top grades early.

How long should I spend revising IGCSE Chemistry?

Start six to eight weeks before the exams for steady, low-stress revision. Spread the 12 topics across those weeks, with about 20 to 30 minutes per session, most days. Spend more time on your weaker topics and on high-value areas like the theory paper. Little and often works far better than a few long cramming sessions at the end.