Wales Β· WJECSyllabus
Chemistry syllabus, dot point by dot point
Every dot point in the Wales Chemistrysyllabus, with a focused answer for each one. Click any dot point for a worked explainer, past exam questions, and links to related dot points. Written by Claude Opus 4.8, Anthropic's latest AI.
Unit 2.2 Acids, bases and salts
Module overview β- What makes a solution acidic or alkaline, and how does the pH scale measure it?Describe the properties of acids and bases, the ions they produce in solution, and use the pH scale and indicators to classify solutions.8 min answer β
- What does neutralisation produce, and what are the products when acids react with metals, bases and carbonates?Describe neutralisation in terms of hydrogen and hydroxide ions and write equations for reactions of acids with metals, bases and carbonates.9 min answer β
- How do we prepare a pure, dry sample of a soluble salt and of an insoluble salt?Describe how to prepare a pure, dry soluble salt from an acid and an insoluble base or carbonate, and how to make an insoluble salt by precipitation.9 min answer β
- How do we test for halide ions, sulfate ions and carbonate ions?Describe tests for halide ions using silver nitrate, sulfate ions using barium chloride, and carbonate ions using dilute acid.8 min answer β
- How do we test for common gases and identify metal ions by flame tests and with sodium hydroxide?Describe tests for hydrogen, oxygen, carbon dioxide and chlorine, flame tests for metal ions, and tests for metal cations using sodium hydroxide solution.9 min answer β
Unit 2.1 Bonding, structure and properties
Module overview β- How do covalent bonds form, and why do simple molecular substances have low melting points?Describe covalent bonding as shared pairs of electrons, draw dot-and-cross diagrams for simple molecules, and relate simple molecular structure to low melting points and poor conduction.9 min answer β
- Why are diamond and graphite so different even though both are made only of carbon?Describe giant covalent structures including diamond and graphite, and relate their bonding and structure to their very different properties.8 min answer β
- How do ionic bonds form, and why do ionic compounds have such high melting points?Describe ionic bonding as electron transfer, draw dot-and-cross diagrams for simple ionic compounds, and relate the giant ionic lattice to the properties of ionic compounds.9 min answer β
- How does metallic bonding explain why metals conduct and bend, and why are alloys harder than pure metals?Describe metallic bonding as positive ions in a sea of delocalised electrons, relate it to metal properties, and explain why alloys are harder than pure metals.8 min answer β
- How can we work out the bonding in a substance from its melting point and conductivity?Use the properties of a substance (melting point, conductivity, state) to deduce its type of bonding and structure.9 min answer β
Unit 2: Crude Oil and Organic Chemistry
Module overview β- What are alcohols, and how is ethanol made and used?Alcohols as a homologous series, the functional group, and the production of ethanol by fermentation and by hydration of ethene.9 min answer β
- How do alkanes and alkenes differ, and why do we crack large hydrocarbons?Alkanes and alkenes as homologous series, the test for unsaturation, combustion of hydrocarbons, and cracking to make smaller alkanes and alkenes.10 min answer β
- What is crude oil, and how is it separated into useful fuels?Crude oil as a mixture of hydrocarbons, separation by fractional distillation, and the properties and uses of the fractions.9 min answer β
- How are plastics made from alkenes, and why are they hard to dispose of?Addition polymerisation of alkenes, drawing the repeat unit, the uses of common polymers, and the problems of polymer waste and disposal.9 min answer β
Unit 2: Metals and their Extraction
Module overview β- Why are alloys often more useful than pure metals, and why do we recycle metals?The properties and uses of alloys, why alloys are harder than pure metals, and the economic and environmental reasons for recycling metals.8 min answer β
- How does electrolysis extract reactive metals, and why is aluminium made this way?Electrolysis of molten ionic compounds, the reactions at the electrodes, and the extraction of aluminium from molten aluminium oxide.10 min answer β
- Why are different metals extracted in different ways, and how is iron made in the blast furnace?Metal ores, extraction by reduction with carbon for metals below carbon in the reactivity series, and the reactions of the blast furnace.9 min answer β
- How do we order metals by reactivity, and what does that order let us predict?The reactivity series, reactions of metals with water and dilute acid, and displacement reactions of metals from solutions of their salts.9 min answer β
Unit 2.4 Chemical reactions and energy
Module overview β- Why is breaking bonds endothermic and making bonds exothermic, and how do we calculate the energy change?Explain bond breaking and bond making in terms of energy and calculate the energy change of a reaction from bond energies.9 min answer β
- How do we show energy changes on a reaction profile, and what makes a reaction exothermic or endothermic?Describe exothermic and endothermic reactions, draw and interpret reaction profiles, and identify activation energy and overall energy change.9 min answer β
- How do temperature, concentration, surface area and catalysts change the rate of a reaction?Describe and explain the effect of temperature, concentration or pressure, surface area and catalysts on rate using collision theory.9 min answer β
- What is the rate of a reaction, and how does collision theory explain it?Define the rate of reaction, describe how it is measured, and use collision theory to explain how reactions occur.9 min answer β
- What is a reversible reaction, and how does changing conditions shift a dynamic equilibrium?Describe reversible reactions and dynamic equilibrium, and predict the effect of changing temperature, concentration and pressure using Le Chatelier's principle.9 min answer β
- How are ammonia and sulfuric acid made industrially, and why are the conditions chosen as a compromise?Describe the Haber process and the Contact process, including their conditions, and explain why the conditions are a compromise between yield, rate and cost.9 min answer β
Unit 1.2 Atomic structure and the Periodic Table
Module overview β- What is inside an atom, and how do isotopes give an element its relative atomic mass?Describe sub-atomic particles and their relative masses and charges, work out particle numbers from atomic and mass number, define isotopes, and calculate relative atomic mass.9 min answer β
- How do we represent chemical reactions, and why is mass always conserved?Represent reactions by word and balanced symbol equations, apply the law of conservation of mass, and classify reactions as exothermic or endothermic.9 min answer β
- How does paper chromatography separate a mixture, and how do we read a chromatogram?Carry out paper chromatography, interpret chromatograms, and calculate and use Rf values to identify substances in a mixture.8 min answer β
- How are electrons arranged in shells, and how does this link to the Periodic Table?Describe the arrangement of electrons into shells for the first twenty elements and relate electronic structure to group and period in the Periodic Table.8 min answer β
- How do elements, compounds and mixtures differ, and how do we tell a chemical change from a physical one?Distinguish between elements, compounds and mixtures, interpret chemical formulae, and tell physical changes apart from chemical reactions.8 min answer β
- How is the Periodic Table organised, and what are the trends in Groups 1, 7 and 0?Describe the arrangement of the Periodic Table, distinguish metals and non-metals, and explain trends in Group 1, Group 7 and Group 0.9 min answer β
Unit 1: The Earth, Atmosphere and Resources
Module overview β- How do human activities change the climate and the quality of the air we breathe?Greenhouse gases and climate change, the combustion products that pollute the air, and the problems each pollutant causes.9 min answer β
- Why is limestone such a useful rock, and what is the limestone cycle?Limestone and its uses, the thermal decomposition of calcium carbonate, the reactions of the limestone cycle, and building materials made from limestone.9 min answer β
- What is the air made of today, and how did the atmosphere change over billions of years?The composition of today's atmosphere, the early atmosphere, and how the proportions of carbon dioxide and oxygen changed over geological time.9 min answer β
- How is drinking water made safe, and how do substances dissolve in water?The water cycle, treatment of water for drinking, the test for water, and solubility including the difference between dilute and concentrated solutions.9 min answer β