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Topic 11: Metals Introduction Pupils should be encouraged to identify the presence and use of metals in the world around them. The social and industrial importance of the metal industry should be discussed, including the finite nature of metal sources and the need for re-cycling. Pupils should be aware that over threequarters of the chemical elements are metals; this topic deals with some properties, uses and reactions of the more common metals and considers why some are found uncombined while others have to be extracted from ores. At General Level, the Learning Outcomes are based on: some understanding of the macroscopic features of metal chemistry an awareness of the idea of reactivity in metals knowledge of ways of extracting metals from ores knowledge of the changes brought about by alloying. At Credit Level, in addition, the Learning Outcomes require knowledge that some metal oxides can be reduced by heating with other substances; the ability to carry out calculations involving percentage composition. Topic 11: Metals Learning Outcomes GENERAL LEVEL (Grades 4, 3) CREDIT LEVEL (Grades 2, 1) Pupils should be able to: and in addition to: 1 State that metals conduct electricity when solid or liquid 2 Relate specific properties of metals, eg density, thermal and electrical conductivity, malleability, strength, to their uses 3 Explain the need for recycling metals in terms of the finite nature of the metal resources 4 Describe the reactions of different metals with oxygen, water and dilute acid 5 State that these reactions give an indication of the reactivity of the metal 6 State that ores are naturally-occurring compounds of metals 7 State that the less reactive metals are found uncombined in the earth’s crust and that the more reactive metals have to be extracted from ores GENERAL LEVEL (Grades 4, 3) CREDIT LEVEL (Grades 2, 1) 8 Explain that the extraction of a metal from its ore is an example of reduction 9 Explain why the inactive metals were among the first to be discovered 10 Give examples of social and industrial factors which resulted in large scale extraction of more reactive metals 11 State that some metals can be obtained from metal oxides by heat alone; some by heating with carbon; and some need other methods Explain in terms of reactivity of the metal why some metals can be obtained from the metal oxides by heat alone; and why some metal oxides need to be heated with other substances, eg carbon or carbon monoxide; and why some metals cannot be obtained by these methods. 12 State that iron is produced from iron ore in the blast furnace 13 State the two key reactions which take place in the blast furnace: production of carbon monoxide reduction of iron oxide 14 State that an alloy is a mixture of metals or of metals with non-metals 15 Give examples of the important uses of alloys, eg brass, solder, “stainless” steel 16 Work out empirical (or molecular) formulae from masses or percentage composition 17 Work out percentage masses of elements in compounds from their names or formulae