Science at key stage 3    (Year 9)

• Provide pupils with a range of questions about metals and non-metals, eg
• Are metals good conductors of heat/electricity?
• Are non-metals non-conductors?
• Are non-metals all gases?
• Where do we get metals (iron, zinc, copper, lead, gold, silver) from?
• What are they used for?
• Suggest sources of information they could use, eg databases, reference books, practical activities.
• Ask different groups to explore different questions and to produce a factsheet about a particular element or property. Help pupils use these to make a comparison of non-metals and metals and to explain what makes metals useful.
• Explain to pupils that there are similarities in the ways in which metals react chemically and that they are going to find out more about these in this unit.

• Demonstrate that a metal, eg zinc, reacts with both hydrochloric acid and sulphuric acid to produce a gas. Establish that the bubbles indicate that a gas is being formed, that this is a new material and that a chemical reaction is taking place. Show pupils the formulae for the two acids and ask them to suggest what the gas might be. Remind them of the test for hydrogen and demonstrate that hydrogen is formed.
• Ask pupils to find out whether similar reactions occur when other metals, eg magnesium, iron, react with hydrochloric acid and to record their results in a table. Establish that hydrogen is produced in each case and, using the names, symbols and formulae for the reactants and hydrogen, ask pupils to suggest what has happened to the metal and where the other product might be found. Using appropriate sample(s), show by evaporation that the salt remains in solution. Using the patterns in the equations, ask pupils to predict what will be made when calcium reacts with hydrochloric and sulphuric acids. Demonstrate the reactions, showing that hydrogen is made.

• Ask pupils to explore what happens when acids, eg hydrochloric, sulphuric, nitric, react with a range of carbonates, eg sodium carbonate, calcium carbonate, copper carbonate. Prompt them with a series of questions, eg
• What is similar about the reactions?
• Is a gas made? How do you know and what is it?
• Are there colour changes?
• Does the test tube get hot or cold?
• Ask pupils to record their observations systematically and to record evidence of a chemical reaction taking place.
• Give pupils the formulae of a variety of metal carbonates and their corresponding chlorides, sulphates and nitrates, and invite pupils in groups to work out the products of some reactions between metal carbonates and acids. Help them to construct word equations. Collect and discuss their predictions, look for any patterns and establish the general word equation.

• Demonstrate, or ask pupils to carry out, a reaction between a metal oxide and an acid (preferably one that produces a coloured salt, eg copper sulphate) and ask pupils for evidence that a chemical reaction has taken place. Separate any excess metal oxide, reminding pupils how to use filtration apparatus, and evaporate the water. Compare the salt formed with a stock sample.
• Help pupils to construct a word equation and, by using the formula, to identify the other product. Ask pupils to explain why this reaction did not produce bubbles. Give pupils the names of some other salts and ask them to suggest which acid and metal oxide would be needed to make them. Display suggestions and ask others to explain whether they are correct or not.

• Ask pupils to work in groups to make individual cards with the names of each reactant, plus signs, arrows and the names of each product for two examples of each of these reactions: acids with metals, acids with metal carbonates, and acids with metal oxides. Each group then shuffles its cards and passes them to another group, which has to sort them into three pairs of word equations, representing three types of reaction of acids, and to write the word, symbol and general equations for their own reactions.

• Remind pupils of work they did earlier on acids and alkalis and establish by quick questioning what they recall. If necessary, demonstrate the use of universal indicator to determine the acidity or alkalinity of a solution. Ask pupils about neutralisation and establish that a neutral solution is one with pH7 and that neutralisation is a chemical reaction. Remind pupils about everyday examples of neutralisation. Explain to pupils that they are going to neutralise hydrochloric acid with potassium hydroxide or sodium hydroxide and to find out exactly how much to add. Ask them to suggest how they could do this and adopt an appropriate technique. Point out the risks of using alkalis.
• Help pupils to carry out or demonstrate the reaction. Establish that potassium chloride or sodium chloride is formed, that sodium chloride is common salt and is an example of the class of compounds called 'salts'. Ask pupils to complete word equations for other neutralisation reactions.

• List the names of salts already encountered in this unit and ask pupils to work out what the names show, eg a part comes from a metal and a part comes from an acid. Ask pupils to use secondary sources to find out the uses of some salts, eg sodium stearate, potassium nitrate, copper sulphate, calcium phosphate, iron sulphate, magnesium sulphate, silver nitrate.

• Prepare cards with the names of some salts that pupils can make easily and another selection of cards with the names of metals or metal compounds that can be used in the preparation. Give groups of pupils a 'salt' card and ask them to select an appropriate 'metal' or 'metal compound' card and to decide which acid they need to use. Include information about the hazards of the starting materials and salts named on the cards. Ask them to make a plan for preparing a sample of the salt. If appropriate, prompt them with a series of questions, eg
• How will you know when all the acid has reacted?
• How will you separate any unreacted solid?
• What will you do to try to get large crystals?
• Encourage pupils to try things out, eg finding out if there is a visible change or if the reactant needs to be heated, and then to prepare their salt. Ask pupils to produce an account of what they did, indicating any difficulties and saying what they did about them.

• Ask pupils to write four or five multiple-choice questions on the work in this unit, clearly identifying the correct answer. Discuss questions with pupils and pass them to others to answer. Review questions with pupils and help them to produce a set with correct answers highlighted.
• Help pupils to collect together and display all the summaries of reactions they have carried out during this unit.