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

Part 1 of 2

Page 01

Reading a formula

define

Try it yourself

Which statement defines the molecular formula of a compound?

define: give the precise meaning.

Choose one answera.The mass of one molecule of the compoundb.The number and type of different atoms in one moleculec.The way the atoms are arranged in space in one moleculed.The simplest whole number ratio of the different atoms in a compound

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Scope and sources

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

Formulae and equations (3.1 Core 1–4, Supplement 5–8): the formulae of the elements and compounds named in the subject content, the molecular formula, a formula from a model or diagram, word and symbol equations with state symbols and, in the Supplement, the empirical formula, ionic formulae from a model or from the charges, ionic equations and symbol equations from given information. Ions and their charges are in Ions and ionic bonding, masses and moles in later modules of topic 3, and the reactions themselves in later modules.

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

Official Cambridge syllabus