Science at key stage 3 (Year 8)
Unit 8E: Atoms and elements
Section 8: Reviewing work
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Objectives |
| Children should learn: |
- to distinguish between elements and non-elements
- to identify the scientific knowledge relevant to a particular question
- to make sure they are working safely
- to explain how their work provides evidence about a question
- to discuss and question what they are learning and how it is relevant when using different variables
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Activities |
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Outcomes |
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Children: |
- Give pupils sets of statements,
eg
- made of only one sort of atom
- symbol C
- formula KF
- made of different atoms joined together
- made of atoms
- gives off carbon dioxide when it is heated
- a solution of salt in water
and ask them to decide whether or not an element is described or whether it is not possible to tell.
- Extend for some pupils with more challenging statements,eg
- formula CO
- symbol Co
- formula O2
- breaks into two new materials when it is heated
- Explain that they are going to test their understanding in a practical activity and provide them with a sample of an 'unknown' material (copper carbonate) and challenge them to find evidence (practical or from data) of whether it is an element. Where necessary, prompt pupils by referring back to the first part of the activity. Ensure that what pupils propose is safe and, where necessary, help them to carry out their plan. Ask pupils to record what they did, their results and to explain what their results show. Discuss pupils' results with them and invite them to ask each other questions about what they did and what it showed. Bring together evidence from all investigations.
- Help pupils to summarise the reactions of copper carbonate in a word equation, making clear which reactants and products are elements and which are compounds. Emphasise that the changes are chemical reactions in which new materials were made.
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- identify statements describing elements and non-elements, explaining their decisions
- identify methods that will provide appropriate evidence,
eg comparison of appearance with appearance of elements; change in mass on heating
- carry out their work safely
- explain how their results provided evidence,
eg it changed colour and lost mass; if an element joins with something else it will gain mass
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Points to note |
- Pupils may suggest a variety of things to do,
eg searching a database of elements.
- Some pupils will need a good deal of help in planning what to do, but are likely to find it easier to explain what their results show.
- Extension: pupils could try to find out what causes the loss in mass. They are likely to have used the lime water test for carbon dioxide in unit 7F 'Simple chemical reactions'. Some pupils could be challenged to think up alternative explanations for their evidence,
eg it lost mass because it combined with oxygen and made carbon dioxide, which escaped, and how to decide between the explanations. It may be helpful with these pupils to introduce the symbol equation for the reaction.
Safety
- copper carbonate is harmful. One product (copper oxide) is an irritant. Eye protection should be used. Teachers will need to check pupils' plans for health and safety, eg that appropriate quantities are to be used, before practical work begins
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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