OCR AS and a Level Chemistry B (Salters) Support Material for SOW Planning

Support material for scheme of work planning

The following guidance sets out suggested teaching times for the Chemistry B (Salters) A Level specification from 2015 (H433). This information can also be used in the context of teaching the Chemistry B (Salters) AS Level specification from 2015 (H033).

The Planning Guidance table on the following pages sets out suggested teaching times for the topics within the specification. Note that we always recommend that individual centres plan their schemes of work according to their individual needs. Actual teaching times for topics will depend on various factors including: i) the amount of practical work done within each topic; ii) the emphasis placed on development of practical skills in various areas; iii) the use of contexts, case studies and other work to support depth of understanding and application of knowledge and understanding; iv) the level of prior knowledge and understanding that learners bring to the course.

An online Scheme of Work builder is available at the OCR website, which will allow centres to create lesson-by-lesson or week-by-week Scheme of Works for their teaching.

The guidance below follows the order of the storylines in the specification. The Chemistry B specification is intended to offer flexibility in teaching, and teachers should consider how to teach the specification so that topics flow naturally. The following guidance should therefore be seen as one of a number of possible ways of structuring the teaching of this course. Further ideas on ordering of the topics of the AS and A Level across a two-year course, can be found in the co-teaching guide. Detailed guidance is also available on how the new specification maps to the legacy specification, and the content of the specification over and above the common subject criteria for Chemistry.

Delivery guides

The column ‘Delivery Guides’ refers to individual teacher guides available from the Chemistry B qualification page and the dedicated Delivery Guides page These Delivery Guides provide a significant source of guidance and suggestions for teaching of individual topics, including links to a range of activities that may be used and guidance on resolving common misconceptions. Other resources, , including Topic Exploration Packs, go into greater depth and provide new activities to support the teaching and learning of the new content within the specification.

Practical work

Module 1.1 (Practical skills assessed in a written examination) is not included explicitly in the guidance below. The expectation is that practical skills are developed through the practical work completed throughout the course and in support of conceptual understanding.

Suggestions for suitable practical work are included throughout this document. This is by no means an exhaustive list of potential practical activities, and any suggested activities should be fully risk assessed before use in your centre.

In the guidance, the abbreviation ‘PAG’ stands for ‘Practical Activity Group’, and refers to the groups defined in Appendix 5h of the A Level specification (H433) .These PAGs form part of the Practical Endorsement in Chemistry, which is part of the A Level qualification only.

There is no internally assessed practical assessment in the AS qualification. However, this does not mean that the development of practical skills should not form part of the teaching and learning at this level. While the Practical Endorsement is only awarded at the A level, practical skills will be assessed in the written examinations at both AS and A Level. Further details are available at the PositiveAboutPractical website, and in the Practical Skills Handbook.

To support the Practical Endorsement, OCR has released three activities for each PAG, which are available at the OCR Interchange: Click Coursework and tasks / Science Co-ordinator materials / GCE From 2015. If you do not have access to these pages, please speak with your Head of Department or your centre’s Exams Officer.

AS learners will benefit from taking part in the practical activities, and will be able to count their performance (assuming adequate records are kept) towards the A Level Practical Endorsement if they decide to proceed to the full A Level after taking the AS examinations. OCR recommends that AS learners join in with any Practical Endorsement activities undertaken in the first year of the A Level course.

The ‘PAG’ references in the guidance indicate topics where completion of individual PAGs would support teaching of the content. It is not compulsory to complete PAGs at these points.

Further guidance of additional practical activities that may be useful is provided by the Royal Society of Chemistry here.

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Document History

• Research and evaluate the evidence on the formation of elements and the development of the atomic structure (HSW1, 6, 7) - a good opportunity for developing presentation skills and peer-assessment.
• RSC SpectraSchool will provide opportunities for practice.

• Main chemical ideas: atomic structure; fusion reactions; mass spectroscopy and isotopes.
• Interpretation of data from mass spectrometry is required, but not the workings of the instruments.
• Knowledge of nuclear fission is no longer required.
• Note that the specification periodic table now follows IUPAC recommendations, showing atomic number at the top and relative atomic mass at the bottom of each element.
• A ‘print-your-own’ A1 sized OCR Periodic Table is available here.

• Carry out flame tests with compounds containing appropriate ions – for example here.
• Atomic and molecular structure provides opportunities for model building and discussion (HSW1, 8).
• Explanation of atomic spectra in terms of electron transitions and the use of ‘dot-and-cross’ diagrams in explaining molecular shape provide opportunities for discussing development of scientific arguments (HSW2).
• Deducing electronic configurations through identification of relationships between first ionisation enthalpy and atomic number provides opportunities for analysis and interpretation of data (HSW5).

• Main chemical ideas: Atomic spectra and electron configuration; the periodic table and Group 2 chemistry; Bonding and shapes of molecules.
• 2.8.8 notation is no longer required.
• Detailed discussion of atomic and electronic structure, including s and p orbital shapes, are studied here.
• The electrostatic nature of covalent bonding and lone pair effects in molecular shapes are now discussed.
• Giant metallic, ionic and covalent-lattice structures are introduced.
• Flames tests are included.
• Knowledge of the EM spectrum from infrared to ultraviolet is required, and use of both c =  and E = h.
• Group numbers now following IUPAC recommendations (1 to 18), i.e. halogens are referred to as Group 17 and noble gases as Group 18.

• PAG 4 – Qualitative analysis of ions
• Test tube or reduced scale reactions involving Group 2 elements and their compounds; reaction of ions noted in EL(s); ion identificiation through a sequence of tests) – resources here.
• These practicals provide opportunities for scientific investigation and risk management (HSW4).
• Synthesis of salts including calculation of percentage yield –for example here.

• Main chemical ideas: the periodic table and Group 2 chemistry; bonding and the shapes of molecules; ions – formulae, charge density and tests.
• The effect of ion charge density on Group 2 carbonate thermal stability, linked to polarisation of the carbonate ion, is required.
• Methods of synthesising salts are required, to include balancing of ionic equations.
• Solubility of compounds from given ions, colours of precipitates and the structure of the sodium chloride-type lattice are required.
• Introduce electronic structure of ions in detail.
• Skills in titration practical and calculations (including unstructured), along with percentage yield calculations are required. The RSC Titration screen experiment is a useful starting point.

• PAG 1 – Moles determination (experiments involving reacting masses and moles).
• PAG 2 – Acid–base titration (making up standard solutions and diluting solutions using volumetric apparatus; acid–base titrations).
• Plenty of practice of chemical calculations should be encouraged - and Calculations in AS/A Level Chemistry, Jim Clark, Longman (ISBN: 9780582411272) are two sources that provide plenty of examples.

• Main chemical ideas: chemical equations and amount of substance (moles); titrations and titration calculations.
• Accurate use of the following terms will be required: acid, base, alkali, neutralisation.

• PAG 3 – Enthalpy determination (experiments to measure the energy transferred when reactions occur in solution or when flammable liquids burn).
• Calculation of enthalpy changes from experimental techniques (HSW2).

• Main chemical ideas: thermochemistry
• A statement of Hess' law is not required, but calculations using the law are.
• Molar gas volume and the gas constant are given on the Data Sheet.
• Molar volume is given to three significant figures (24.0 dm3 mol–1 at RTP), and the gas constant to four significant figures (8.314 J mol–1 K–1).
• Accurate use of the following terms will be required: exothermic, endothermic, standard conditions, (standard) enthalpy change of reaction (rH), (standard) enthalpy change of combustion (cH), (standard) enthalpy change of formation (fH), (standard) enthalpy change of neutralisation (neutH).

• Catalytic cracking of paraffin offers opportunities for development of risk assessments and manipulative skills – for example here.

• Main chemical ideas: organic chemistry: names and combustion of alkanes and alcohols.
• Accurate use of the following terms will be required: average bond enthalpy, catalyst, catalysis, catalyst poison, heterogeneous, cracking, aliphatic, aromatic, arene, saturated, unsaturated, functional group and homologous series.
• Octane numbers and the effect of isomerisation, reforming and cracking on hydrocarbon performance do not need to be discussed.
• Arenes can be represented as the 'delocalised electron' model or the 'polyene' model.

• PAG 7 – Qualitative analysis of organic functional groups (testing compounds for unsaturation using bromine water).

• Main chemical ideas: organic chemistry: names and combustion of alkenes; heterogeneous catalysis; reactions of alkenes; addition polymers; electrophilic addition.
• Accurate use of the following terms will be required: addition, electrophile, carbocation.
• Discussion of bonding now includes ideas of sigma and pi bonding.
• Discussion of reactions (including mechanisms) and isomerisation of alkenes, and formation of polymers are discussed here.

• PAG 1 – Moles determination (experiments involving volumes of gas).
• Considering the benefits and risks of using fossil fuels and alternative fuels (HSW9).
• Considering the environmental implications of atmospheric pollutants and extracting minerals from the ocean (HSW10).

• Main chemical ideas: organic chemistry: names and combustion of alcohols; gas volume calculations; shapes of organic molecules (- and -bonds); structural and E/Z isomers (CIP rules not required); dealing with polluting gases.
• The ideal gas equation should be taught. Particular emphasis should be placed on accurate use of units and plenty of practice is required.
• Entropy has been moved to 2nd year study, but may be worth mentioning now for those requiring stretch-and-challenge.

• PAG 4 – Qualitative analysis of ions.
• Electrolysis of aqueous solutions, e.g. copper chloride and sodium chloride – for example here.
• Redox reactions in test-tube and/or reduced scale, including of halogens and their compounds – for example here.
• Using oxidation states to balance simple redox equations (HSW3).
• Techniques and procedures in the electrolysis of aqueous solutions (HSW4).

• Main chemical ideas: Halogen chemistry; redox chemistry and electrolysis.
• Explanations of the properties of halogens is required in OZ, but could be taught here to maintain the continuity of the chemistry.
• Balancing simple redox equations should be introduced here.

• Iodine–thiosulfate redox titrations.
• Using ideas of 'opposing change' to predict the effect of changing conditions on equilibrium position (HSW3).
• Techniques and procedures in iodine and thiosulfate titrations (HSW4).
• Considering the risks associated with the transport and use of chlorine (HSW9).
• Considering the use of chlorine in sterilising water (HSW10).
• Le Chatelier's principle provides opportunities for modelling and developing problem solving skills.

• Main chemical ideas: equilibria.
• Iodine–thiosulfate titrations are a new context. Liberated iodine can be measured using thiosulfate titrations, using starch as an iodine indicator, giving a clear endpoint. Titration and redox calculations can be taught here.
• This is a key area of mathematical skills development. Plenty of practice is recommended.

• Demonstrate the reactions of concentrated sulfuric acid on sodium chloride, bromide and iodide to produce hydrogen halides. Reaction of these gases with ammonia demonstrates their acidic nature. Their thermal stability with a red-hot glass rod can also be demonstrated.
• Using experimental observations to explain the reactions between sodium halides and concentrated sulfuric acid (HSW5).

• Main chemical ideas: Halogen chemistry; equilibrium; atom economy.
• Reactions of sulfuric acid with hydrogen halides should be carefully discussed.