Contents

States of matter

Atoms, elements and compounds

Stoichiometry

Electrochemistry

ElectrolysisBeing prepared
Electrolysis of solutions and electroplatingBeing prepared
Fuel cellsBeing prepared

Chemical energetics

Chemical reactions

Acids, bases and salts

Acids, bases and indicators
OxidesBeing prepared
Making saltsBeing prepared

The Periodic Table

Reading the tableBeing prepared
Group I: the alkali metalsBeing prepared
Group VII: the halogensBeing prepared
Transition elements and noble gasesBeing prepared

Metals

Metals and alloysBeing prepared
The reactivity seriesBeing prepared
CorrosionBeing prepared
Extracting metalsBeing prepared

Chemistry of the environment

WaterBeing prepared
FertilisersBeing prepared
Air quality and climateBeing prepared

Organic chemistry

Naming organic moleculesBeing prepared
Crude oil and alkanesBeing prepared
AlkenesBeing prepared
Alcohols and carboxylic acidsBeing prepared
PolymersBeing prepared

Experimental techniques and chemical analysis

Mixtures and separation
Measuring and planning experimentsBeing prepared
Crystallisation
Distillation
Paper chromatography
Choosing methods and checking purityBeing prepared
TitrationBeing prepared
Gas testsBeing prepared
Anion testsBeing prepared
Cation and flame testsBeing prepared

Independent final check

Page 03

Explain without the key

describe / explain / calculate / deduce

Final check

A cycle shop sells a dry lubricant for bike chains that is mostly graphite powder, and a tile cutter whose wheel is edged with tiny diamonds. (a) Describe the bonding in graphite, and explain why the graphite lets the links of the chain move freely. (b) Describe the bonding in diamond, and explain why the wheel cuts through hard tiles but is hardly worn itself. (c) Supplement: a watch keeps time with a tiny quartz crystal, which is silicon(IV) oxide. The crystal contains 2.0 × 10¹⁹ silicon atoms. Ignoring the atoms at its surface, calculate the number of oxygen atoms in the crystal and the number of silicon–oxygen bonds. (d) Supplement: a hard white solid stays solid above 1500 °C, scratches glass, and does not conduct electricity, either as a solid or when molten. A pupil says: “It must be ionic, because it has such a high melting point.” Explain why the pupil is incorrect, and deduce the type of structure the solid has.

describe: give the features or what happens. explain: give reasons and connect them to evidence. calculate: work out the answer from the data. deduce: reach a conclusion from the information given.

Build your answer

(a) The graphite lubricant

(b) The diamond tile cutter

(d) Supplement: why the pupil is incorrect, and the type of structure

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Scope and sources

Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.

Giant covalent and metallic structures (2.6 Core 1–2, Supplement 3–4; 2.7 Supplement 1–2): the giant covalent structures of diamond and graphite and their uses in cutting tools, as a lubricant and as an electrode, the giant covalent structure of silicon(IV) oxide and its similarity in properties to diamond, metallic bonding as the attraction between positive ions in a giant metallic lattice and a sea of delocalised electrons, and the electrical conductivity, malleability and ductility of metals. Simple molecules, ionic lattices, alloys, the uses of metals and electrolysis are left to other modules.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus