- Demonstrate making or invite pupils to make a mixture from two elements: sulphur (powder) and iron (powder). Ask pupils to heat a mixture of iron and sulphur in ignition tubes until they observe a red glow and, after their tube has cooled, to extract the contents and try to find out if it still contains a mixture or if a new chemical (compound) has been made. Through discussion of their results, establish that they have made a compound. Help pupils to write picture and word equations for the reaction.
- Demonstrate that the compound iron sulphide behaves differently from its constituent elements sulphur and iron,
eg by adding a small amount of dilute acid to both and observing the differences in the way the mixture behaves compared to the compound.
- Ask pupils for names of compounds they have used,
eg water, carbon dioxide, copper carbonate; provide them with samples and ask them to compare the compounds with the elements from which they are made. Establish, through discussion of the formulae of some of the oxides made in unit 8E 'Atoms and elements',
eg magnesium, sodium and aluminium oxides, that compounds are made from elements in fixed proportions. Provide pupils with drawings or software simulations showing particles in examples of elements, compounds and various mixtures of elements and/or compounds. Ask them to identify the types of particles present and what the drawings represent in terms of elements, compounds and mixtures.
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- describe differences between compounds and the elements from which they are made
- interpret formulae for compounds in terms of the relative numbers of atoms of different elements
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