Bukit Timah parents considering Cambridge IGCSE Chemistry tuition should confirm syllabus 0620, the examination year, the student’s Core or Extended entry and the practical-assessment option. The 2026–2028 course assesses theory, multiple-choice reasoning and practical skills. Effective support connects what students observe with particle explanations, chemical symbols and calculations, so that they can explain an unfamiliar reaction rather than reproduce a memorised answer.

A three-student tutorial can provide useful discussion and individual correction when each learner also solves questions independently. Bring a marked school paper, a recent calculation and the school’s component information to the first meeting. This guide explains what to look for; it does not confirm an available Chemistry class, laboratory, fee or timetable. Any practical provision and safety arrangements must be checked directly with the school or provider.

• Course: Cambridge IGCSE Chemistry 0620, distinct from combined-science qualifications.
• Examination-year focus: 2026–2028.
• Core: Papers 1 and 3; grades C–G.
• Extended: Papers 2 and 4; grades A*–G.
• Practical component: Paper 5 Practical Test or Paper 6 Alternative to Practical.
• Teaching priorities: accurate particle models, formulae, equations, quantitative reasoning and evidence-based explanations.

Understand the examination route

For 2026–2028, multiple choice contributes 30%, theory 50% and practical assessment 20%. The multiple-choice paper lasts 45 minutes, and the theory paper lasts 1 hour 15 minutes. Core candidates use Papers 1 and 3; Extended candidates use Papers 2 and 4. Both routes also require either Paper 5, a 1 hour 15 minute Practical Test, or Paper 6, a one-hour Alternative to Practical. These arrangements and the content boundaries are in the official 0620 syllabus.

Do not interpret Alternative to Practical as permission to ignore experimental understanding. Students still need to reason about apparatus, observations, measurements, variables and limitations. School practical experience and tuition-based interpretation can complement one another, but a provider should not claim laboratory access that it does not have.

The Cambridge Chemistry subject page provides syllabus updates and later examination-year documents. This guide was checked on 15 November 2026. Its worked examples are original illustrations, not official questions or a complete list of examinable content. Cambridge IGCSE and Singapore’s SEC are separate qualifications.

Diagnose the level at which understanding breaks down

Chemistry often asks students to move between three representations: an observable event, an explanation involving particles and a symbolic equation. A student may describe bubbles correctly but not identify the gas. Another may write a balanced equation yet be unable to explain what the coefficients represent. A third may understand the reaction but make a numerical error when calculating quantities.

A useful diagnostic tests all three levels. Ask for an observation, a particle explanation, an equation and a short calculation from a supplied reaction. Include a question about a practical method as well. The tutor should listen to how the learner chooses a step, not only check the final answer. This reveals whether the problem is chemical knowledge, mathematical fluency, language precision or interpreting the task.

Keep a first attempt before correction. A completed page produced with repeated hints can look secure while the student remains unable to begin a fresh problem. Later use a different reaction that tests the same principle. Improvement is more convincing when the learner recognises the relationship without being told the chapter or formula.

For parents, a useful report is specific: “the student confuses a coefficient with a formula subscript,” or “the student converts mass to moles but does not use the equation ratio.” Those statements identify what should be taught next. A general instruction to memorise more reactions may miss the actual difficulty.

Particles and changes of state

Start by distinguishing a substance from the arrangement and movement of its particles. When ice melts, the water molecules do not become larger or turn into a different substance. Their arrangement and freedom of movement change. A diagram should show the relevant differences without suggesting that a particle itself expands into a liquid droplet.

Heating can increase particle motion, but a temperature change is not the only possible consequence of transferring energy. During a change of state, energy can be involved in overcoming attractions without the temperature rising in the simple way a student might expect. Ask the learner to explain a heating curve in sections rather than attach one sentence to the entire graph.

Evaporation and boiling also need distinction. Evaporation can occur at a liquid’s surface below its boiling point; boiling occurs throughout the liquid under the relevant conditions. “The water disappears” is an observation of the container, not a complete account of what happens to the particles. The material has entered the gas phase rather than ceased to exist.

When comparing diffusion in gases and liquids, connect the explanation to particle movement and spacing. Avoid saying that particles move because they want to spread out. A useful teaching question asks what changes in the model and what remains the same when the temperature or state changes.

Atoms, ions and isotopes

An atom’s proton number identifies the element. Changing the number of electrons can produce an ion without changing that identity. Changing the number of neutrons can produce a different isotope of the same element. Students who treat every particle change as a change of element need to return to these distinctions before moving into bonding or electrolysis.

In a neutral atom, the numbers of protons and electrons are equal. A positively charged ion has fewer electrons than protons; it has not acquired extra protons during an ordinary chemical reaction. The tutor can ask the learner to account for the charge numerically rather than memorise “positive means lost” without understanding why.

Isotopes have the same proton number but different neutron numbers. Their relative abundance can affect the relative atomic mass used in calculations. A weighted average is not simply the midpoint between isotope masses unless the proportions make that appropriate. A small numerical example can connect the chemical idea to familiar average calculations.

Use clear notation and distinguish mass number from relative atomic mass. The first describes the total of protons and neutrons in a particular nucleus; the second is an average relative quantity for the element. Reading the symbol carefully prevents errors that later appear as incorrect formula masses or particle counts.

Bonding: describe the attraction, not only the electron diagram

An ionic-bonding explanation should connect electron transfer to the formation of oppositely charged ions and their electrostatic attraction. Drawing arrows between atoms is only part of the story. The resulting ionic solid is a lattice, not simply a collection of isolated pairs that retain the appearance of the original dot-and-cross sketch.

Covalent bonding involves shared electron pairs. A student should be able to connect a displayed formula to the atoms and bonds present, while recognising that different substances have different overall structures. A simple molecular substance and a giant covalent structure cannot be given the same property explanation merely because both involve covalent bonds.

Metallic bonding can be explained through positive ions and delocalised electrons. This model helps connect electrical conduction with mobile charge carriers. It also provides a basis for discussing why layers can move without the whole structure simply losing all attraction. The explanation should relate the model to the property asked about.

A useful comparison question gives three substances with different structures and asks why their melting points or conductivities differ. The student must identify the relevant particles, attractions and mobility. A statement such as “it has strong bonds” is too vague unless the answer specifies which attractions must be overcome in the process under discussion.

Structure and properties: avoid convenient overgeneralisations

For a simple molecular substance, melting or boiling usually involves overcoming intermolecular attractions rather than breaking every covalent bond within each molecule. Confusing these two levels can produce an incorrect explanation of a low boiling point. Ask the student to draw a boundary around one molecule and identify which interactions occur inside and between those boundaries.

An ionic compound may conduct when molten or in an appropriate aqueous solution because ions can move, while its solid form does not provide the same mobility. The presence of charged particles alone is not sufficient; the charges must be able to move through the material. This distinction is especially useful when learners incorrectly attribute all electrical conduction to electrons.

Giant covalent structures require their own explanation. Students should not assume that every covalent substance has a low melting point, nor that every form of an element has identical properties. The arrangement and bonding of atoms matter. The tutor can use a comparison to expose the limits of a rule before it becomes an examination mistake.

When answering a property question, name the structure, identify the relevant interaction or charge carrier, and connect it to the observed property. This sequence is a reasoning aid, not a compulsory script. The final answer should fit the substance and process rather than repeat the same paragraph for every material.

Formulae and equations: conserve the atoms

Balance the reaction between magnesium and oxygen as 2Mg + O₂ → 2MgO. There are two magnesium atoms and two oxygen atoms on each side. The coefficients change the amounts represented; the formula MgO remains unchanged. Writing MgO₂ merely to balance oxygen would describe a different composition rather than repair the equation.

Students should distinguish the coefficient before a formula from the subscript within it. Two water molecules contain four hydrogen atoms and two oxygen atoms, whereas changing H₂O to H₂O₂ changes the substance. A short particle drawing can make this distinction easier to see than a verbal rule alone.

For ionic formulae, total positive and negative charges must balance in a neutral compound. A magnesium ion with charge 2+ and chloride ions with charge 1− give MgCl₂. The subscript records the ratio needed for electrical neutrality. It is not selected by copying a number from a neighbouring element without considering charge.

State symbols and conditions should be used where required and understood rather than added as decoration. An aqueous substance is dissolved in water; it is not necessarily a pure liquid. Reading these distinctions carefully helps when interpreting ionic equations, precipitation and electrolysis.

Mole calculations: follow a chain of quantities

Consider an original example using relative atomic masses Mg = 24 and O = 16. If 2.4 g of magnesium reacts completely with sufficient oxygen, the amount of magnesium is 2.4/24 = 0.10 mol. The balanced equation shows a 1:1 mole ratio between Mg and MgO, so 0.10 mol of MgO forms. With a formula mass of 40, the product mass is 4.0 g.

The increase in mass does not violate conservation: oxygen has joined the magnesium. A student who expects the product mass always to equal the mass of the initially weighed solid has ignored a reactant. Asking where every atom comes from connects the calculation to the chemistry rather than treating it as a sequence of divisions.

Label each stage: mass, amount in moles, equation ratio, then the requested quantity. The mole ratio comes from a balanced equation, not from comparing formula masses. A calculation can use correct arithmetic throughout and still be wrong if that ratio has been selected incorrectly.

For solution calculations, keep concentration units consistent with volume units. A volume stated in cubic centimetres may need conversion before it is combined with a concentration per cubic decimetre. Write the conversion explicitly until the student can perform it reliably. Dimensional checking is a useful defence against an answer that is too large by a factor of one thousand.

Limiting reactants, yield and purity

When two reactants are supplied, the smaller mass is not automatically the limiting reactant. Compare the available amounts with the equation ratio. A substance with a small mass may represent many moles, while a larger mass of another substance may still be insufficient for the required proportions. The reaction model determines the comparison.

The theoretical yield follows from the limiting amount under the stated model. The actual recovered amount can be smaller because a reaction is incomplete, product is lost during transfer or other relevant processes occur. A student should connect an explanation to the experiment rather than list every possible source of loss indiscriminately.

If the theoretical product mass is 10.0 g and 8.0 g is obtained, the percentage yield is 80%. The denominator is the theoretical amount. Reversing the fraction gives a misleading result. A reported yield above 100% should prompt questions about impurities, residual solvent, measurement or assumptions, not a conclusion that extra atoms have appeared.

Purity is a different ratio: the amount of desired substance relative to the total sample. A high percentage yield and high purity are not the same claim. Ask learners to state in words what each numerator and denominator represents before substituting numbers.

Acids, bases and salts: organise reactions by what changes

Acid–base learning becomes clearer when students identify the reacting species and the products rather than memorise unrelated examples. An acid reacting with a suitable metal oxide can form a salt and water. The name of the salt depends on the acid and the metal-containing reactant; it should not be guessed from the word “neutralisation” alone.

Distinguish a base from an alkali. An alkali is a soluble base, so the two terms are related but not identical. Similarly, concentrated and strong describe different ideas: concentration concerns how much solute is present per volume, while strength concerns the extent of ionisation in the relevant context. Treating the words as synonyms creates avoidable confusion.

In a school titration context, the purpose of careful measurement is to determine the reacting quantities. The student should understand the endpoint observation, the significance of repeated measurements and how the equation connects the measured amounts. A memorised list of apparatus does not establish that understanding.

Salt-preparation questions require attention to solubility and the substances involved. A suitable method for an insoluble product is not automatically suitable for a soluble one. Practical work must follow supervised school procedures; this guide offers conceptual distinctions, not instructions for mixing household or laboratory chemicals at home.

Redox and electrolysis: track electrons and moving ions

Oxidation and reduction can be understood through electron transfer. Oxidation is loss of electrons and reduction is gain. In a displacement example, a metal that becomes a positive ion has lost electrons, while the ion converted to a neutral metal has gained them. The two processes are connected rather than independent labels applied arbitrarily.

Students should account for charge in a half-equation as well as atoms. If a species gains two electrons, the written equation must reflect the change in charge. This is another conservation check: a visually balanced set of symbols can still be wrong if the charges do not balance.

In electrolysis, ions move through the electrolyte while electrons move through the external circuit. Do not describe electrons as simply flowing through the liquid in the same way as through a metal wire. Identifying the charge carriers helps the learner understand why an ionic solid and a molten ionic substance behave differently.

Products depend on the electrolyte and conditions, including whether the substance is molten or aqueous. The presence of water changes the possible species involved. A tutor should teach the applicable selection rules from the student’s syllabus and use safe, supervised demonstrations only. Predicting an examination product is not a reason to attempt an unsupervised electrolysis experiment.

Energetics: breaking and forming bonds have opposite energy effects

Breaking bonds requires energy; forming bonds releases energy. The overall energy change depends on the balance between those contributions. A common misconception is that energy is released simply because bonds are broken. Correcting that statement early makes later reaction-profile and bond-energy questions more coherent.

For an exothermic reaction, the products lie at a lower energy level than the reactants in the usual reaction-profile representation. An activation-energy barrier can still be present. A reaction releasing energy overall does not mean it begins without any initiating energy under all conditions.

A catalyst provides an alternative pathway with a lower activation energy. It does not change the overall energy difference between the same reactants and products. On a diagram, students should therefore change the height of the pathway barrier without moving the starting and ending levels merely because a catalyst has been added.

When interpreting temperature measurements, distinguish the reacting system from its surroundings. A rise in the surrounding solution’s temperature can provide evidence of energy transfer from an exothermic process, subject to the setup and limitations. The explanation should identify what is being measured rather than assume that every temperature change has the same cause.

Rate of reaction: slope and final amount answer different questions

On a graph of product volume against time, a steeper initial gradient indicates a faster initial rate. The final plateau indicates the total measured product under those conditions. Two reactions can reach the same final volume at different speeds. A student who calls the higher final volume “the faster reaction” has confused amount with rate.

Collision-based explanations should identify what changes. Increasing concentration can increase the frequency of relevant collisions. Increasing temperature changes particle energies and the proportion of collisions with enough energy to react. Increasing surface area exposes more of a solid to contact. These explanations are related but should not be collapsed into one vague statement that particles “react more.”

A fair comparison holds other relevant conditions constant. If both concentration and temperature change between trials, the results may not isolate the effect of concentration. Ask the student to name the variable actually changed, the measurement used for rate and the controls needed for that specific method.

Repeating a measurement can help assess variability, but an improvement must address a real limitation. “Repeat for accuracy” is not a complete explanation if the main problem is gas escaping before measurement begins. The tutor should encourage specific links between a source of error, its effect and a feasible improvement.

Reversible reactions and equilibrium

A reversible reaction can proceed in both directions. At dynamic equilibrium in a closed system, forward and reverse reactions continue at equal rates, so the macroscopic composition remains constant. The reactions have not stopped, and the amounts of reactants and products do not have to be equal.

This distinction is useful because students often interpret “balanced” as equal quantities. Ask them to imagine two equal flows between containers that already hold different amounts. The analogy can illustrate constant levels without equal starting quantities, while the tutor should make clear that it is only a model for the rate relationship.

Changes in conditions can alter the equilibrium position, depending on the reaction. Students should use the actual equation and conditions rather than memorise that a particular change always increases yield. A catalyst changes how quickly equilibrium is reached but does not change the equilibrium position for the same conditions.

For industrial-context questions, separate yield, rate, cost and safety. A condition that favours equilibrium yield may not give the most practical overall process. A reasoned explanation acknowledges the relevant trade-off instead of assuming that maximising one quantity automatically solves the whole decision.

Organic chemistry: use structure to organise reactions

Organic names and formulae become easier to manage when students identify carbon chains, functional groups and bonding patterns. An alkane and an alkene should not be distinguished only by a remembered name ending. The presence of a carbon–carbon double bond changes the structure and helps explain a different pattern of reactions.

Ask the learner to move between a molecular formula and a displayed or structural representation, while recognising that a molecular formula may not specify one unique arrangement. Counting atoms carefully provides a check. A neat drawing is not correct if carbon has been assigned an inconsistent number of bonds.

For a homologous series, look for the shared functional group and systematic changes between members. Avoid turning the general formula into a substitute for recognising the actual structure. The student should explain why a particular molecule belongs to a family and which feature is relevant to the reaction being discussed.

In polymer questions, distinguish the monomer from the repeating unit and the larger chain. The representation should show how units connect rather than simply place several complete monomer drawings beside one another. Use the syllabus’s required examples and notation, and label any additional classroom illustration as extension rather than an examination requirement.

Separation, chromatography and evidence

A separation method should exploit a relevant difference in properties. Filtration can separate an insoluble solid from a liquid, but it does not remove a dissolved solute merely because the solution looks coloured. Distillation involves differences in volatility. Chromatography separates components through their differing behaviour in the chosen system. Students should explain the property used, not only name apparatus.

In an original chromatography calculation, a spot moving 3.0 cm while the solvent front moves 7.5 cm has an Rf value of 0.40. Both distances are measured from the same baseline. Rf is a ratio without units. Comparisons need appropriate conditions; a numerical match from unrelated systems is not automatically conclusive identification.

Observations and conclusions must be kept separate. “A white precipitate formed” records an observation. “The sample contains a particular ion” is an interpretation that depends on the test, other evidence and possible alternatives. Students should not replace an observation with the name of the substance they hoped to find.

Cambridge’s current materials include qualitative-analysis information for the relevant practical papers. Learners still need to interpret it accurately and connect a result to a conclusion. Having access to a reference sheet does not remove the need to read conditions, distinguish similar observations or reason through a sequence of tests.

Practical work, safety and meaningful evaluation

Practical tuition should operate within verified facilities, trained supervision and appropriate risk assessment. Do not assume a small classroom is a laboratory. Parents should ask what is actually provided and how it relates to the school’s practical programme. All chemical handling should follow the institution’s instructions; online teaching examples are not permission for home experimentation.

In written practical reasoning, identify the measurement and its limitations. A measuring instrument’s resolution, a subjective endpoint, heat transfer to surroundings and loss of material are different issues. A useful evaluation explains how a particular limitation could affect the result and how a proposed change addresses it.

Do not automatically remove an anomalous value because it spoils a pattern. Check the procedure, repeat where appropriate and explain the decision. A conclusion should reflect the evidence collected and the range investigated. Scientific reasoning is strengthened by acknowledging a justified limitation, not weakened by it.

How a small group can develop independent chemistry

A shared lesson on a reaction can assign different roles: one student balances the equation, another explains the particles and another checks a quantitative result. Rotate the roles so that each learner experiences all three forms of reasoning. Then use a fresh reaction for individual work. The independent task reveals whether the discussion has become usable knowledge.

Different starting points require different follow-up. A student struggling with formulae should not be rushed into difficult mole calculations before charge and composition are secure. A student with reliable calculations may need more practice interpreting observations. An extending learner can explain why a plausible alternative answer fails. Small-group value comes from this responsiveness.

Home practice should include a short retrieval task, one unfamiliar application and correction of a meaningful error. Later, mixed questions can test whether the learner selects the right concept without a heading. A long paper is not always the best homework when one prerequisite is blocking several topics.

Reviewing progress and choosing a workable timetable

Compare independent work over time. Look for fewer formula errors, more reliable equation ratios, clearer particle explanations and more specific practical evaluation. A high score on a repeated worksheet is less informative than a sound solution to a new problem. Record when a hint was needed so that supported and independent performance are not confused.

Weekday or weekend tuition should fit the student’s energy, travel and school workload. Confirm the actual tutor’s experience with 0620, the class size, fees, absence policy and any practical limitations. A subject page is not proof of a current vacancy or a particular facility.

A review after several lessons should decide what to maintain and what to change. No fixed twelve-week plan guarantees an examination grade. The aim is a sustainable cycle in which the student increasingly identifies the relevant chemistry, chooses a method, checks it and explains the result without the tutor supplying each step.

Frequently asked questions

Is Chemistry mainly memorisation?

Accurate recall matters, but students also need to apply particle models, balance equations, calculate quantities and interpret evidence. A list of facts alone is not enough.

Does Paper 6 mean practical learning can be skipped?

No. Alternative to Practical assesses experimental understanding in a written format. Ask how the learner will develop those skills.

Why can a student calculate correctly and still lose the reasoning?

The arithmetic may be sound while the chemical equation, mole ratio, unit conversion or interpretation is wrong. Diagnose the first incorrect decision rather than repeating the entire calculation blindly.

Can a tutor guarantee an A*?

No. Look for a clear teaching process and evidence of independent improvement, not a promised outcome.

Official references and related guides

Consult the 0620 subject page and 2026–2028 syllabus. Related guides cover Biology, Physics and Mathematics. Confirm the candidate’s entry with the school or examination centre before choosing revision materials.