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9. Metals

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  1. 9.1 Properties of metals

    1. • Compare the general physical properties of metals and non-metals, (a) thermal conductivity (b) electrical conductivity (c) malleability and ductility (d) melting points and boiling points

    2. • Describe general chemical properties of metals, limited to their reactions with: (a) dilute acids (b) cold water and steam (c) oxygen

  2. 9.2 Uses of metals

    1. • Link metal uses to properties: aluminium for aircraft (low density), overhead cables (low density/conductivity), food containers (corrosion resistance); copper wiring (conductivity/ductility)

  3. 9.3 Alloys and their properties

    1. • Describe an alloy as a mixture of a metal with other elements, (a) brass as a mixture of copper and zinc (b) stainless steel as a mixture of iron and other elements such as chromium, nickel and carbon

    2. • State: alloys can be harder and stronger than the pure metals and are more useful

    3. • Describe uses of alloys in terms of their physical properties, including stainless steel in cutlery because of its hardness and resistance to rusting

    4. • Identify representations of alloys from diagrams of structure

    5. • Explain why alloys can be harder/stronger than pure metals: different-sized atoms stop layers sliding easily

  4. 9.4 Reactivity series

    1. • State the order of the reactivity series as: potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold

    2. • Describe reactions of metals with water/steam/acids: potassium, sodium and calcium with cold water; magnesium with steam; magnesium, zinc, iron, copper, silver and gold with dilute hydrochloric acid; link to reactivity series

    3. • Deduce an order of reactivity from a given set of experimental results

    4. • Describe relative reactivities of metals in terms of their tendency to form positive ions, by displacement reactions, if any, with the aqueous ions of magnesium, zinc, iron, copper and silver

    5. • Explain the apparent unreactivity of aluminium in terms of its oxide layer

  5. 9.5 Corrosion of metals

    1. • State the conditions required for the rusting of iron and steel to form hydrated iron(III) oxide

    2. • State some common barrier methods, including painting, greasing and coating with plastic

    3. • Describe how barrier methods prevent rusting by excluding oxygen or water

    4. • Describe use of zinc in galvanising as an example of a barrier method and sacrificial protection

    5. • Explain sacrificial protection in terms of the reactivity series and in terms of electron loss

  6. 9.6 Extraction of metals

    1. 9.6.1Ease in obtaining metals from their

      • Describe ease in obtaining metals from their ores, related to the position of the metal in the reactivity series

    2. 9.6.2Iron extraction from hematite in a

      • Describe iron extraction from hematite in a blast furnace: coke burns for heat/CO2; CO2 is reduced to CO; CO reduces iron(III) oxide; limestone decomposes to calcium oxide; slag forms. Symbol equations not required

    3. 9.6.3Main ore of aluminium is bauxite and

      • State: the main ore of aluminium is bauxite and that aluminium is extracted by electrolysis

    4. 9.6.4Symbol equations for the extraction of

      • State the symbol equations for the extraction of iron from hematite (a) C + O2 → CO2 (b) C + CO2 → 2CO (c) Fe 2O3 + 3CO → 2Fe + 3CO2 (d) CaCO 3 → CaO + CO2 (e) CaO + SiO2 → CaSiO3

    5. 9.6.5Aluminium extraction from purified

      • Describe aluminium extraction from purified bauxite/aluminium oxide: role of cryolite, why carbon anodes are replaced, and electrode reactions with ionic half-equations. Bauxite purification not required