Topic 9 - Metals

9.1 Properties of metals
9.2 Reactivity series
9.3 Extraction of metals
9.4 Iron
9.5 Aluminium

9.1 Properties of metals
(a) describe the general physical properties of metals (as solids having high melting and boiling points; malleable; good conductors of heat and electricity) in terms of their structure

(b) describe an alloy as a mixture of a metal with another element, e.g. brass; stainless steel
(c) identify representations of metals and alloys from diagrams of structures
(d) explain why alloys have different physical properties from their constituent elements

9.2 Reactivity series
(a) place in order of reactivity: aluminium (see also 9.5(b)), calcium, copper, (hydrogen), iron, lead, magnesium, potassium, silver, sodium and zinc by reference to
(i) the reactions, if any, of the metals with water, oxygen, steam and dilute hydrochloric acid,

(ii) the reduction, if any, of their oxides by carbon and/or by hydrogen
(b) describe the reactivity series as related to the tendency of a metal to form its positive ion, illustrated by its reaction with
(i) the aqueous ions of the other listed metals
(ii) the oxides of the other listed metals

(c) deduce the order of reactivity from a given set of experimental results

(d) describe the action of heat on the carbonates of the listed metals and relate thermal stability to the reactivity series

9.3 Extraction of metals

(a) describe the ease of obtaining metals from their ores by relating the elements to their positions in the reactivity series

(b) describe metal ores as a finite resource and hence the need to recycle metals

(c) discuss the social, economic and environmental advantages and disadvantages of recycling metals, e.g. aluminium and copper

9.4 Iron

(a) describe and explain the essential reactions in the extraction of iron using haematite, limestone and coke in the blast furnace

(b) describe steels as alloys which are a mixture of iron with carbon and often other metals and how controlled use of these additives changes the properties of the iron, e.g. high carbon steels are strong but brittle whereas low carbon steels are softer and more easily shaped

(c) state the uses of mild steel (e.g. car bodies; machinery) and stainless steel (e.g. chemical plant; cutlery; surgical instruments)

(d) describe the essential conditions for the corrosion (rusting) of iron as the presence of oxygen and water; prevention of rusting can be achieved by placing a barrier around the metal (e.g. painting; greasing; plastic coating; galvanising)

(e) describe the sacrificial protection of iron by a more reactive metal in terms of the reactivity series where the more reactive metal corrodes preferentially (e.g. underwater pipes have a piece of magnesium attached to them)

9.5 Aluminium

(a) outline the manufacture of aluminium from pure aluminium oxide dissolved in cryolite (starting materials and essential conditions, including identity of electrodes should be given together with equations for the electrode reactions but no technical details or diagrams are required)

(b) explain the apparent lack of reactivity of aluminium

(c) state the uses of aluminium and relate the uses to the properties of this metal and its alloys, e.g. the manufacture of aircraft; food containers; electrical cables