GCSE Combined Science: Trilogy from Edexcel Science ... - AQA

Switching to AQA from Edexcel: Science and Additional Science (Chemistry) If you're thinking of switching to AQA from Edexcel Science and Additional Science (2SC01 and 2SA01) for teaching from September 2016, this resource will provide a helpful comparison of the subject content and assessment for each awarding body.

It directly compares the Chemistry components of the current Edexcel Science and Additional Science with the Chemistry component of the new AQA GCSE Combined Science: Trilogy specification (8464).

The subject contents and required practicals for GCSE Combined Science: Trilogy are also in the GCSE Chemistry specification (8462), so there is flexibility to co-teach or to move students between courses.

Comparison overview Most of the content is common to both specifications, although the emphasis and style is different. AQA specification focuses on the effects of chemistry in our world.

Assessment New AQA specification Current Edexcel specification

Two externally assessed written papers of (1 hour 45 minutes).

Paper 1 assesses sections 1 to 5 of the subject content.

Paper 2 assesses sections 6 to 10, but may also include the fundamental principles in sections 1 to 3.

Five required practicals should be carried out by students and may be examined in the written papers to assess practical skills.

Two externally assessed written papers (1 hour):

• Paper 1 examines unit C1

• Paper 2 examines unit C2.

Controlled assessment(s) for internal assessment of practical skills.

Content

Practicals

New AQA specification Current Edexcel specification

The required practicals are clearly listed, as are opportunities for development of skills identified in the right-hand column of the specification. These should encourage more practical work which will motivate students and encourage the transfer of skills across the subject.

Each of the two units includes practical investigations which may be externally examined, as well as further suggestions for practical work. Internally assessed Controlled assessment tasks are taken from these investigations.

Working scientifically


Specification reference: WS 1.1 to WS 4.6

Specification reference: How Science Works

'Working scientifically' encompasses all the activities that scientists do. It is woven throughout the specification and written papers. There are cross-references to relevant skills development opportunities in the subject content.

There is no cross-referencing to Working Scientifically skills in the subject content.

5.1 Atomic structure and the periodic table

5.1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes


Specification reference:

5.1.1.1 Atoms, elements and compounds


• C1 0.1 to 0.3

• C2.13a

• C2 2.5

This is a summary of the skills which a student will need throughout all


topics in terms of using names, symbols and various types of equation. Much of this is spread throughout the current Edexcel specification.

A definition of a compound.

Higher Tier: Half-equations and ionic equations.

Risk assessments for practical work and hazard symbols.

Specification reference: 5.1.1.2 Mixtures

Specification reference: C2 3.8 to 3.10

Both specifications include the separation of mixtures by fractional distillation and chromatography.

A definition of a mixture, filtration, distillation and simple distillation

The separation of two immiscible liquids.

Specification reference: 5.1.1.3 Scientific models of the atom

Specification reference: C2 1.3

Both specifications describe the nuclear model of the atom.

The historical development of different models of the atom.

N/A


5.1.1.4 Relative electrical charges of subatomic particles


C2 1.5 to 1.8a

The content is identical in both specifications.


5.1.1.5 Size and mass of atoms


• C2 1.4

• C1.6

• C1.8b

• C1.10

Both specifications describe the relative sizes of the atom and nucleus, and the relative masses of the proton, neutron and electron.

The actual sizes of the nucleus and atom.

Students of all abilities: isotopes; calculation of the number of protons, neutrons and electrons in

Higher Tier: the treatment of isotopes. It goes into more detail than AQA, looking at the effect of the existence of isotopes on relative atomic mass.


an atom or ion.


5.1.1.6 Electronic structure


C2 1.12


5.1.2 The periodic table



5.1.2.1 The periodic table


• C2 1.9

• C1.13

• C4.1

The content is almost identical in both specifications.

Prediction of possible reactions and reactivity from position in the periodic table.

N/A


5.1.2.2. The development of the periodic table


C2 1.1

Both specifications describe how Mendeleev developed the periodic table.

Early periodic tables before Mendeleev.

N/A


5.1.2.3 Metals and non-metals


C2 1.2

Both specifications describe the position of metals and non-metals in the periodic table.

The differences between metals and non-metals in terms of the ions they form and their characteristic physical and chemical properties.

N/A

Specification reference: Specification reference:


5.1.2.4 Group 0 C2 4.14 to C4.17

Both specifications cover the lack of reactivity of the noble gases and the trends in physical properties.

N/A The discovery and uses of the noble gases.


5.1.2.5 Group 1


C2 4.6 to 4.8

Both specifications cover typical physical properties of the alkali metals and their reaction with water.

Low density of the metals, colour and solubility of compounds.

Higher Tier: explanation of the pattern of reactivity.


5.1.2.6 Group 7


C2 4.9 to 4.13

Both specifications cover the reaction of the halogens with metals and non-metals and displacement reactions of halogens with metal halides leading to the trend in reactivity.

The trend in relative molecular mass, melting point and boiling point and the existence as diatomic molecules.

The reaction of metals includes the formation of ions with a -1 charge. The reaction with non-metals is more general.

Recall of colours and physical states of the halogens at room temperature.

The reaction with non-metals is restricted to the reaction with hydrogen to produce hydrogen halides which form acids in water.

'Displacement reactions of halogens' is a required practical.

N/A In C2 4.4, the Edexcel specification also includes a consideration of transition metals in terms of their high melting points and the formation of coloured compounds.

5.2 Bonding, structure and the properties of matter

5.2.1 Chemical bonds, ionic, covalent and metallic



5.2.1.1 Chemical bonds


C2 2.1

This is an introduction to the types of bonding. The detailed content is spread throughout the Edexcel specification but not summarised in the same way as in the AQA specification.


5.2.1.2 Ionic bonding


C2 2.2 to 2.5

Both specifications deal with ionic bonding as electron transfer, using sodium chloride as an example.

The relation of charge on the ions to the group number.

The terms cation and anion, ions as charged groups of atoms, and the endings -ide and -ate in names of compounds.


5.2.1.3 Ionic compounds


C2 2.7 (Only Higher Tier)

The description of an ionic compound as a lattice, with strong electrostatic forces, is included in both specifications, but is only for Higher Tier in the Edexcel specification, unlike AQA.

Dot-and-cross, ball-and-stick and space-filling diagrams with a consideration of their limitations. Students are expected to deduce:

• that a compound is ionic

• the empirical formula from a diagram.

N/A


5.2.1.4 Covalent bonding


C2 3.1 to 3.3

The description of covalent bonding, as sharing of pairs of electrons, is very similar in both specifications, although the examples are different. Two of the examples in the Edexcel specification are for Higher Tier only. Both include dot-and-cross diagrams.


Large molecules such as polymers and giant structures, including silicon dioxide.

The limitations of different types of diagram including ball-and-stick, 2D and 3D representations. Students are expected to deduce the molecular formula of a substance from a given model or diagram.

N/A


5.2.1.5 Metallic bonding


C2 4.2

The content is almost the same.

AQA focuses on 2D and 3D representations.

5.2.2 How bonding and structure are related to the properties of substances



5.2.2.1 The three states of matter

Description of the particle model of the three states of matter.

Changes of state, including the prediction of the state of a substance at different temperatures given appropriate data.

This topic is not covered in the Edexcel specification although an understanding of most of the ideas is assumed in other areas such as fractional distillation of oil or liquid air, and the effect of gas pressure on equilibrium.


5.2.2.2 State symbols


• C1

• C2 0.3



5.2.2.3 Properties of ionic compounds


• C2 2.7 to 2.8

• C4.5


Both specifications describe and explain the high melting and boiling point and electrical conductivity of ionic substances.

Edexcel Higher Tier: the explanation of the properties.

AQA students of all abilities: the description and the explanation of the properties.


5.2.2.4 Properties of small molecules


• C2 3.5

• C4.5

The content is almost identical. Both specifications describe and explain the low melting and boiling point and lack of electrical conductivity of substances consisting of small molecules.

The idea that intermolecular forces increase with size of molecules.

N/A


5.2.2.5 Polymers

N/A

This topic deals with the size of the molecules, the strength of bonding and intermolecular forces of polymers, linked to their properties as solids at room temperature.

N/A


5.2.2.6 Giant covalent structures


• C2 3.6

• C4.5

Both specifications deal with the difference between simple molecular and giant covalent substances. Both refer to diamond and graphite, and the AQA specification also includes silicon dioxide.


5.2.2.7 Properties of metals and alloys


• C1 4.10 to 4.11

• C2 4.3

• C4.5


The content is very similar. Both specifications use models to explain the difference in properties between pure metals and alloys.

The strength of metallic bonding, linked to most metals having high melting and boiling points.

The uses of metals in relation to their properties are included here (covered in AQA section 5.10.3.2).


5.2.2.8 Metals as conductors


C2 4.3

Both specifications describe and explain electrical conductivity.

A description and explanation of conduction of thermal energy.

N/A

N/A Section C2 4.5 is a classification of elements and compounds as four main structure types, with their properties.

As well as the properties in the AQA specification, it includes relative solubility in water.

There is also a required practical investigation of structure type.

5.2.3 Structure and bonding of carbon



5.2.3.1 Diamond


• C2 3.7

• C4.5

The content is almost identical, but the Edexcel specification includes the use of diamond in cutting tools (Higher Tier only).


5.2.3.2 Graphite


• C2 3.7

• C4.5



The conduction of thermal energy. Higher Tier: the use of graphite as electrodes and as a lubricant.


5.2.3.3 Graphene and fullerenes

N/A

5.3 Quantitative chemistry

5.3.1 Conservation of mass and the quantitative interpretation of chemical equations



5.3.1.1 Conservation of mass and balanced chemical equations


• C1 2.13 b, c

• C2.16

The content is very similar, but there is no clear link between conservation of mass and balanced chemical equations in the Edexcel specification.


5.3.1.2 Relative formula mass


C2 6.1

The content is very similar, but there is no clear link between the sum of the relative formula masses and balanced chemical equations in the Edexcel specification.


5.3.1.3 Mass changes when a reactant or product is a gas

N/A

5.3.2 Uses of amount of substance in relation to masses of pure substances



5.3.2.1 Moles

N/A

The Avogadro constant and the mole as applied to formulae, equations and particles.

N/A



5.3.2.2 Amounts of substances in equations


C2 6.5

Refers to moles but does not specify a method for reacting mass calculations.

N/A

5.3.2.3 Using moles to balance equations (Higher Tier only)

5.3.2.4 Limiting reactants (Higher Tier only)

5.3.2.5 Concentration of solutions (Higher Tier only)

N/A

N/A Specification reference:

C2.6.2 to 6.4

Calculation of percentage composition and empirical formulae.

There is a required practical to determine an empirical formula.


C2 6.6 to 6.11.

Calculation of percentage yield, with reasons for a reaction not giving 100% yield.

Understanding of waste products and their problems, and chemists in industry working to find the economically most favourable reactions.

5.4 Chemical changes

5.4.1 Reactivity of metals



5.4.1.1 Metal oxides


C1 4.5

Oxidation and reduction are defined in terms of gain and loss of oxygen in both specifications. Only the AQA specification refers to the reaction of metals with oxygen.


5.4.1.2 The reactivity series

This topic is not covered in the Edexcel specification, although reference is made to the reactivity series in the context of metal extraction, C1 4.3


5.4.1.3 Extraction of metals and reduction


C1 4.1 to 4.6

The content is similar in both specifications; the emphasis is on carbon reduction and position in the reactivity series. Extraction by electrolysis (aluminium) is included here in the Edexcel specification, but covered in the Electrolysis topic in the AQA specification.

N/A There is a practical investigation of methods for extracting a metal from its ore.


5.4.1.4 Oxidation and reduction in terms of electrons

N/A

5.4.2 Reactions of acids



5.4.2.1 Reactions of acids with metals

N/A


5.4.2.2 Neutralisation of acids and


• C1 3.4 to 3.5


salt production • C2 2.6

The content is the same in both specifications.


5.4.2.3 Soluble salts

N/A

There is a required practical to prepare a pure, dry sample of a soluble salt from an insoluble oxide or carbonate.

N/A


5.4.2 4 The pH scale and neutralisation

This topic is not covered in the Edexcel specification.

However, in sections C1 3.1 - 3.3 there is the production of hydrochloric acid in the stomach and indigestion remedies, including a required practical investigation.


5.4.2.5 Strong and weak acids (Higher Tier only)

N/A

5.4.3 Electrolysis



5.4.3.1 The process of electrolysis


C1 3.6

Electrolysis in terms of movement and discharge of ions.

The Edexcel specification only describes electrolysis as a process using electrical energy to decompose compounds.


5.4.3.2 Electrolysis of molten ionic compounds


C1 4.2b

The Edexcel specification only refers to this in the context of the extraction of aluminium.



5.4.3.3 Using electrolysis to extract metals


C1 4.2b

The AQA specification includes details of the extraction of aluminium.

The Edexcel specification only requires knowledge that electrolysis is used.


5.4.3.4 Electrolysis of aqueous solutions


C1 3.6 to 3.7

The specification includes rules for which product is produced at each electrode, leading to prediction of the products of electrolysis of aqueous solutions containing a single ionic compound.

There is a required practical investigating the electrolysis of solutions with inert electrodes.

The specification includes only the electrolysis of hydrochloric acid (without explanation of the electrode processes).

Electrolysis of hydrochloric acid is a required practical.

5.4.3.5 Representation of reactions at electrodes as half-equations (Higher Tier only)

N/A

5.5 Energy changes

5.5.1 Exothermic and endothermic reactions



5.5.1.1 Energy transfer during exothermic and endothermic reactions


C2 5.1 to 5.3

The content is very similar. Both specifications include a required practical, although these have slightly different aims and use different examples.


Conservation of energy during reactions; uses and applications of exothermic and endothermic reactions.

N/A


5.5.1.2 Reaction profiles


C2 5.6

The content is very similar, except that the Edexcel specification is Higher Tier only and does not include knowledge of activation energy.


5.5.1.3 The energy change of reactions


• C2 5.4

• C5.5

The topic is for Higher Tier only in the AQA specification, but is for students of all abilities in the Edexcel specification. Both include a description of bond breaking as being endothermic and bond making as exothermic, with the consequent effect on the overall energy change.

Calculation of energy transfer from bond energies.

There is a required practical comparing the temperature rise when the same volume of water is heated by different fuels (C1 5.24).


C1 5.21 requires knowledge that energy can be provided by a simple hydrogen-oxygen fuel cell.

5.6 The rate and extent of chemical change

5.6.1 Rate of reaction



5.6.6.1 Calculating rates of reactions

N/A


5.6.1.2 Factors which affect the rates of chemical reactions


• C2 5.8 to 5.9


• C5.12

The content is very similar in the two specifications. Both include a required practical, although this is restricted to the effect of concentration changes in the AQA specification.

The effect of gas pressure, the idea of surface area to volume ratio for solids and three specific methods for investigating rates.

Knowledge that reaction rates can vary from very fast to very slow.


5.6.1.3 Collision theory and activation energy


C2 5.10 to 5.11

The content is similar; both specifications deal with the effect of changing the frequency and energy of particle collisions.

AQA: the whole topic is for students of all abilities.

Edexcel: everything except the idea that reactions occur when particles collide is for Higher Tier only.

Explanation of the effect of changing temperature, concentration and pressure in terms of collision theory, including the idea of activation energy.

An explanation of the effect on rate of changing size of pieces of solid, in terms of surface area to volume ratio.

The Edexcel specification is less specific.


5.6.1.4 Factors that increase the rate of reaction


C2 5.10 to 5.11

The content is very similar, although the Edexcel specification is less detailed.

AQA: students of all abilities.

Edexcel: Higher Tier only.

Use of simple ideas about proportionality when using collision theory.

N/A



5.6.1.5 Catalysts


C2 5.12 to 5.13

The AQA specification is much more detailed.

Only the recall of the effect of a catalyst on a reaction rate is common to both specifications.

• definition of a catalyst

• specificity of catalysts

• enzymes as catalysts

• explanation of catalytic action in terms of lowering activation energy

• effect of a catalyst on a reaction profile.

The use of catalytic converters in cars.

5.6.2 Reversible reactions and dynamic equilibrium



5.6.2.1 Reversible reactions

5.6.2.2 Energy changes and reversible reactions

5.6.2.3 Equilibrium

5.6.2.4 The effect of changing conditions on equilibrium (Higher Tier only)

5.6.2.4 The effect of changing conditions on equilibrium (Higher Tier only)

5.6.2.5 The effect of changing concentration (Higher Tier only)

5.6.2.6 The effect of temperature changes on equilibrium (Higher Tier only)

5.6.2.7 The effect of pressure changes

N/A


on equilibrium (Higher Tier only)

5.7 Organic chemistry

5.7.1 Carbon compounds as fuels and feedstock



5.7.1.1 Crude oil, hydrocarbons and alkanes


• C1 5.1 to 5.2

• C5.25 to 5.26

The content is very similar, although the general formula for alkanes is not included in the Edexcel specification.

The formation of crude oil and recognition of other substances, as alkanes from their formula.

N/A


5.7.1.2 Fractional distillation and petrochemicals


C1 5.3 to 5.4

The content is very similar in both specifications.

An explanation of fractional distillation is required, along with an awareness of the vast array of natural and synthetic carbon compounds. There is reference to solvents, lubricants, polymers and detergents as derivatives of crude oil.

Edexcel doesn’t require details of fractional distillation, but covers specific uses of different fractions, including bitumen (not mentioned in the AQA specification).


5.7.1.3 Properties of hydrocarbons


C1 5.5 to 5.6

The content is almost identical, but writing balanced equations for combustion reactions is Higher Tier only in the Edexcel specification, unlike AQA where the whole topic is for students of all abilities.


5.7.1.4 Cracking and alkenes


C1 5.27 to 32


The content is very similar, although the Edexcel specification requires a description of cracking in the laboratory whereas the AQA specification requires knowledge of the industrial conditions. Writing balanced equations for cracking reactions is Higher Tier only in the Edexcel specification, unlike AQA where it is for students of all abilities.

Reference to alkenes as starting materials for many other chemicals.

Modern life depends on the uses of hydrocarbons (the Edexcel specification only refers to polymers).

Students do not need to know the names or formulae of individual alkenes.

Higher Tier: the use of data on the composition of different crude oils and demand for the fractions.

Recall of the formulae and structures of ethene and propene.


C1 5.33 to 5.37 covers addition polymerisation, and the uses and problems of disposal of polymers.

5.8 Chemical analysis

5.8.1 Purity, formulations and chromatography



5.8.1.1 Pure substances

N/A


5.8.1.2 Formulations

N/A


5.8.1.3 Chromatography


C2 3.10 to 11

The content is similar in the two specifications; both require calculation of Rf values.


An explanation of how chromatography works, including stationary phase and mobile phase; reference to different solvents.

There is a required practical on chromatography and calculation of Rf values.

The topic is dealt with in the contexts of the food industry and forensic science.

5.8.2 Identification of common gases



5.8.2.1 Test for hydrogen


C1 3.8


5.8.2.2 Test for oxygen


C1 3.14


5.8.2.3 Test for carbon dioxide


C1 5.7


5.8.2.4 Test for chlorine


C1 3.9

The content for all four tests is identical in both specifications.


C2 2.15 to 2.16 covers the analysis of metal ions by flame tests and spectroscopy; the detection of carbonate, sulfate and chloride ions.

5.9 Chemistry of the atmosphere

5.9.1 The composition and evolution of the Earth's atmosphere



5.9.1.1 The proportions of


C1 1.7 to 1.9a


different gases in the atmosphere


N/A A required practical to investigate the proportion of oxygen in the atmosphere.


5.9.1.2 The Earth's early atmosphere


C1 1.1 to 1.5


The presence of nitrogen, methane and ammonia.

N/A


5.9.1.3 How oxygen increased


C1 1.6



5.9.1.4 How carbon dioxide decreased


C1 1.6

The content is almost identical.

However, the AQA specification refers to the formation of coal, crude oil and limestone. The Edexcel specification only refers to limestone.

5.9.2 Carbon dioxide and methane as greenhouse gases



5.9.2.1 Greenhouse gases


C1 5.13

The content is similar, but the AQA specification is more detailed, describing the greenhouse effect in terms of the interaction of radiation of different wavelengths with matter.


5.9.2.2 Human activities which contribute to an increase of


• C1 1.9b


greenhouse gases in the atmosphere • C5.14

• C5.16

The content is very similar, but the AQA specification includes the decomposition of rubbish in landfill sites contributing to an increase in greenhouse gases.


5.9.2.3 Global climate change

The potential effects of climate change are not covered in the Edexcel specification.


5.9.2.4 The carbon footprint and its reduction


• C1 5.15

• C5.17 to 5.19

• C5.22 to 5.23

The ideas in the two specifications are similar, although the methods of reduction of carbon footprint are different.

• definition of carbon footprint

• ideas of energy conservation

• carbon taxes and licenses

• carbon off-setting and carbon neutrality

• problems of reducing the carbon footprint.

• iron seeding of oceans

• biofuels as an alternative to fossil fuels

• hydrogen as an alternative to petrol as a fuel in cars.

5.9.3 Common atmospheric pollutants and their sources



5.9.3.1 Atmospheric pollutants from fuels


• C1 5.8

• C5.11

Both specifications deal with the production of carbon, carbon monoxide and sulfur dioxide.

• coal as a fuel

• production of oxides of

N/A


nitrogen

• prediction of the combustion products of a fuel given appropriate information.


5.9.3.2 Properties and effects of atmospheric pollutants


• C1 5.9 to 5.10

• C5.12

The content is similar in both specifications, although the AQA specification includes more effects.

• respiratory problems caused by sulfur dioxide and oxides of nitrogen

• oxides of nitrogen causing acid rain

• the effects of particulates.

The context of incomplete combustion in appliances using carbon compounds as fuels.

Factors that make a good fuel (section C1 5.20)

5.10 Using resources

5.10.1 Using the Earth's resources and obtaining potable water



5.10.1.1 Using the Earth's resources and sustainable development

There is no equivalent topic in the Edexcel specification, although sections C1 5.18 - 5.23 touch on some of the principles.


5.10.1.2 Potable water (including a required practical on distillation of salt solution)

N/A


5.10.1.3 Waste water treatment

N/A


5.10.1.4 Alternative methods of extracting metals

N/A

5.10.2 Life cycle assessment and recycling



4.10.2.1 Life cycle assessment

N/A


4.10.2.2 Ways of reducing the use of resources


C1 4.9

Most of this topic is not covered in the Edexcel specification; it considers only recycling of metals.

5.10.3 Using materials



5.10.3.1 Corrosion and its prevention


C1 4.7 to 4.

Both specifications discuss corrosion of metals, but in different detail.

Conditions needed for rusting, methods of prevention of corrosion, including corrosion inhibitors and sacrificial protection.

The protective oxide layer on aluminium.

The relation of a metal's resistance to corrosion to its position in the reactivity series.

Prevention of corrosion is not covered.

Edexcel content no longer required

The following topics are not included in the new DfE subject content:

• Specification reference: C1 2.1 to 2.6

Igneous, sedimentary and metamorphic rocks

• Specification reference: C1 2.17 to 2.12, 2.14 to 2.15, 2.17 to 2.18

Limestone, decomposition of metal carbonates, calcium oxide and calcium hydroxide


Corrosion of metals and its prevention


Solubility rules for common types of substance, preparation of insoluble salts by precipitation, uses of barium sulfate

GCSE Combined Science: Trilogy from Edexcel Science ... - AQA

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