Science at key stage 3    (Year 9)

• Show pupils a range of metal objects or pictures of objects, eg copper and nickel coins, gold rings, an old gold necklace, a relatively new rusty hinge, a tarnished silver cup, a photograph of a bronze/copper roof, and ask them to describe what has happened to each and what has caused this. Elicit ideas about the effect of air/water and the different effects on different metals.
• Extend to show pieces of potassium, sodium and lithium, which are shiny when freshly cut but which immediately tarnish on exposure to air. Ask pupils to explain why the surfaces become dull. Challenge pupils to say whether these are metals or not, asking them to produce reasons for and against. Refer back to work on the periodic table.

• Ask pupils whether metals react with water or not, giving their reasons. Invite them to explore the reaction of some familiar metals, eg iron, zinc, magnesium, copper. Ask pupils to predict whether the rapidly tarnishing metals seen in the previous activity would react with water. Demonstrate the reactions to test their predictions.
• Use a safe method to show that hydrogen and an alkaline solution are produced, eg place a small piece of lithium in a beaker of water and collect the gas produced in a test tube. Ask pupils to identify similarities and differences in the reactions of potassium, sodium and lithium with water. Establish an order of reactivity of these metals and help pupils to write word equations. Extend by showing pupils a video clip of the reactions of rubidium and caesium with water. Compare the reactions of the alkali metals with those of the other metals used earlier and agree a tentative order of reactivity. Show pupils the hazard-warning labels on alkali metal containers and ask why they are kept under oil.

• Remind pupils of work they did in unit 9E 'Reactions of metals and metal compounds' on the reactions of acids with metals and ask them what is formed. Help them to write word equations. Ask pupils to carry out quick reactions between either sulphuric acid or hydrochloric acid and filings of coarse metal mesh, eg copper, iron, zinc, magnesium, and from their observations decide the order of reactivity. Ask them which observations they took account of, to compare the reactions of hydrochloric and sulphuric acid, and then to agree an order of reactivity. Compare this with what was established in the previous activity.

• Remind pupils that metals also react with oxygen (or the oxygen in the air) to form oxides. Ask them about word equations. Ask pupils to use their proposed reactivity series to suggest how readily different metals would react, and then use a mixture of demonstration and video clips to test whether the predictions are supported. Point out that in establishing a reactivity series, more secure evidence than qualitative observations is needed. Establish with pupils that, in terms of the evidence collected, the order of reactivity of metals with oxygen is generally similar to that with water and with acids.

• Provide pupils with small samples of metals, eg magnesium, iron, copper, zinc, and solutions of metal salts, eg zinc sulphate, iron (II) sulphate, copper sulphate, silver nitrate. Ask pupils to plan tests of combinations of metal and metal salt to find out if there is a reaction, recording their results in a table. Ask pupils to find a pattern in their results and, if possible, to reorder their table to show the results more clearly. Discuss the results with the pupils and use an analogy or model to explain the displacement of the less reactive metal by the more reactive one. Ask pupils to predict whether other reactions will occur.
• Show using an analogy, eg 'pull' of metal on the sulphate, and word or symbol equations that whether there is a reaction or not depends on the metal and the metal in the salt, not on the acid from which the salt was derived.
• If appropriate, link to work pupils have done on the voltages of simple cells.

• Demonstrate the thermit reaction between iron (III) oxide and aluminium. Ask pupils to explain where the energy to melt the iron produced comes from, and explain, eg using a video clip, the use of the reaction in welding. Use the displacement model to describe what is taking place during the reaction.

• Provide pupils with an activity series of metals (including some that they haven't tested, eg aluminium, lead, silver) and help them make a summary sheet showing reactions of the metals.
• Tell pupils the position in a series of an unknown metal and ask them to predict its reactions. Give pupils information about the reactions of metals not already in the series and ask them to predict where they might come.
• Discuss with pupils any difficulties in coming to decisions.

• Introduce the activity with a short video illustrating the range and uses, and possibly extraction, of metals.
• Ask pupils to use secondary sources, together with their own knowledge of metals to find the answers to a series of questions of varying difficulty, eg
• Why is sodium not used for cutlery?
• Why is a light metal like magnesium not used for car bodies?
• Why has so much gold jewellery survived from ancient civilisations?
• Why was bronze used before iron?
• Aluminium is much more abundant than iron, so why wasn't it used until the beginning of the twentieth century?
• Which metals are found naturally?
• What are the sources of magnesium? Why is it not found naturally?
• How are metals recycled?
• Ask pupils to present their findings and help them to organise the points to produce an information leaflet linking metals' reactivity to their uses (including when they were first used).

• Review what pupils remember about the reactions of acids with metals and remind them of how they compared their reactivity. Explain that they are going to investigate more systematically the differences in reactivity of zinc, magnesium and aluminium with hydrochloric acid. Discuss the indicators, eg changes in temperature, amount of gas produced, that might be measured and which variables they will need to control. Help pupils plan and carry out their investigations safely and, where appropriate, present their results as graphs. Ask pupils to tell the story of what the graphs show and to explain whether the results are what they expected from the relative positions of the metals in the reactivity series. Remind them of earlier work on the extraction of aluminium. Discuss with pupils the key points in this investigation and help them to write an account that brings these out clearly.

• Prepare a short test on the content of the unit, eg using comprehension and data-handling questions about different metals, together with additional questions to provide practice materials. Discuss the additional questions with pupils, eg by asking them to read questions out loud, discuss what the questions mean and what sort of answers are required before they take the test. When pupils have taken the test and it has been marked, discuss their answers to the test questions in a similar way. Provide real (or made-up) answers to some questions and ask pupils to identify good and bad points in each.