KS3 Chemistry

1. KS3 Chemistry 9F Patterns of Reactivity

2. Contents 9F Patterns of Reactivity Metals and water Metals and oxygen Metals and acid Reactivity series and displacement Summary activities

3. Metals and water The Romans used lead to make water pipes but didn’t know that lead reacts slowly with water and makes itpoisonous! Some metals react vigorously with water, some metals react slowly and some do not react at all. What is the best type of metal to use for water pipes?

4. Metals and water – general equation metal water metal hydroxide hydrogen Potassium and sodium are metals that react vigorously with water even when a small amount of each metal is used. When a metal reactswith water, the products are a metal hydroxide and hydrogen gas. What is the general equation for the reaction of a metal with water? What is the test that a metal hydroxide is produced?

5. Metals and water – equations potassium lithium sodium + + + water water water    What are the products when each metal reacts with water? What is the balanced symbol equation for each reaction? lithium hydroxide + hydrogen sodium hydroxide + hydrogen potassium hydroxide + hydrogen

6. Metals and water – observations Metal Reaction with water lithium Bubbles of gas are given off quite quickly. When tested with universal indicator the water is now alkaline. sodium The sodium melts and skims over the surface producing a stream of small bubbles. Sometimes a yellow-orange flame appeared. potassium Potassium immediately produces a lilac flame as it skims around the surface making a fizzing noise. James investigated how reactive some metals are when they react with water and made these observations. Which of these metals is the most reactive with water? Which of these metals is the least reactivewith water?

7. Metals and water – more observations Metal Reaction with water magnesium Reacts slowly with cold water but reacts quickly with steam. copper No reaction. silver No reaction. No reaction. gold James investigated how reactive other metals are with water and made these observations. Copper is used in plumbing and silver and gold in jewellery. Why are these unreactive metals suitable for such uses?

8. Metalsandwater–using unreactivemetals The words “plumber” and “plumbing” come from plumbum (the Latin word for lead) because the ancient Romans used lead for their water pipes. Lead reacts very slowly with water making it poisonous, so this metal is no longer used in plumbing. Copper is a much better metal for water pipes because it does not react at all with water – plumbers should be renamed coppers!

9. Put the following metals in order of reactivity based on their reaction with water, starting with the most reactive: copper,gold,magnesium,lithium,potassium,silver,sodium. Metals and water – order of reactivity potassium sodium lithium magnesium copper, silver, gold

10. Contents 9F Patterns of Reactivity Metals and water Metals and oxygen Metals and acid Reactivity series and displacement Summary activities

11. Metals and oxygen – general equation metal oxygen metal oxide Most metals will react with oxygen. Some metals react faster than others and some may react very slowly or not at all. Magnesium, for example, burns in oxygen with a bright flame. The magnesium reacts with oxygen to produce magnesium oxide. When a metal does reactwith oxygen, the product is a metal oxide. What is the general equation for the reaction of a metal with oxygen?

12. Metals and oxygen – equations magnesium copper iron + + + oxygen oxygen oxygen    What are the products when each metal reacts with oxygen? What is the balanced symbol equation for each reaction? magnesium oxide copper oxide iron oxide

13. Metals and oxygen – observations Metal Reaction with oxygen magnesium The ribbon burned with a dazzling white flame giving grey-white smoke and ash. copper The copper turnings went through reds and oranges and then slowly got a permanent coating of black. iron The iron filings glowed red and sparkled leaving a brown-black looking solid. Shaida investigated how reactive some metals are when they react with oxygen and made these observations. Which of these metals is the most reactive with oxygen? Which of these metals is the least reactivewith oxygen?

14. Metals and oxygen – order of reactivity Put the following metals in order of reactivity based on their reaction with oxygen, starting with the most reactive: copper, iron, magnesium. magnesium iron copper

15. Contents 9F Patterns of Reactivity Metals and water Metals and oxygen Metals and acid Reactivity series and displacement Summary activities

16. Metals and acid – the acid test The first scientists to study chemistry were called alchemists. They were interested in many things including finding ways of changing cheap metals into gold. Some were very good at making metals look gold. Acid was used to find out if gold objects were made of real or fake gold. Most metals react with strong acids. Gold is such an unreactive metal that it does not react with strong acids. This became known as “the acid test” because it stopped tricksters making false claims that something was gold. The phrase “the acid test” is used today to mean any process that will reveal fakes.

17. Metals and acid – experiment

18. Metals and acid – general equation metal acid metal salt hydrogen Gold is an unreactive metal that does not react with acid. Other metals, such as magnesium and zinc, react with acid producing bubbles of gas. The “squeaky pop” test shows that this gas is hydrogen. When a metal reacts with acid, the products are a metal salt and hydrogen. What is the general equation for the reaction of a metal with acid? How does the type of acid affect the type of salt produced?

19. Metals and hydrochloric acid – equations zinc magnesium aluminium + + + hydrochloric acid hydrochloric acid hydrochloric acid    Whatismadewheneachmetalreactswithhydrochloricacid? What is the balanced symbol equation for each reaction? magnesium chloride + hydrogen aluminium chloride + hydrogen zinc chloride + hydrogen

20. Metals and sulfuric acid – equations zinc magnesium aluminium + + + sulfuric acid sulfuric acid sulfuric acid    What is made when each metal reacts with sulfuric acid? What is the balanced symbol equation for each reaction? magnesium sulfate + hydrogen aluminium sulfate + hydrogen zinc sulfate + hydrogen

21. Metals and nitric acid – equations zinc magnesium aluminium + + + nitric acid nitric acid nitric acid    What is made when each metal reacts with nitric acid? What is the balanced symbol equation for each reaction? magnesium nitrate + hydrogen aluminium nitrate + hydrogen zinc nitrate + hydrogen

22. Metals and acid – observations Greg investigated how reactive some metals are with hot and cold acid and made these observations. Which of these metals is the most reactive with acid? Which of these metals is the least reactivewith acid?

23. Metals and acid – order of reactivity Put the following metals in order of reactivity based on their reaction with acid, starting with the most reactive: aluminium, calcium, copper, iron, lead, magnesium, zinc. calcium magnesium aluminium zinc iron lead copper

24. Metals and acid – reactivity activity

25. Contents 9F Patterns of Reactivity Metals and water Metals and oxygen Metals and acid Reactivity series and displacement Summary activities

26. Comparing orders of reactivity When the orders of reactivity of metals with water, oxygen and air are compared, there is a pattern of results. Combining the information from all the reactions of metals with water, oxygen and air gives an overall order of reactivity called the reactivity series.

27. The reactivity series The reactivity series is the list of metals placed in order of their reactivity. One way to remember this order is to learn this silly sentence: potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold Please send Charlie’s monkeys and zebras in lead cages securely guarded! increasing reactivity

28. What is the order of metals?

29. Using the reactivity series The reactivity series can be used to make predictions about the reactions of metals. potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold • Predictions can be made about simple reactions of metals with oxygen, water and acids. • Predictions can also be made about more complex reactions where one metal is competing with another. increasing reactivity

30. Simple reactions – predictions Use the reactivity series to predict if a reaction will take place and how intense the reaction will be. potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold no reaction fizzing burns vigorously very slow reaction burns moderately

31. When does displacement happen? less reactive metal more reactive metal less reactive metal compound more reactive metal compound + +  less reactive metal more reactive metal compound + no reaction  The reactivity series can be used to predict if a metal will react with a metal compound (e.g.chloride,nitrateorsulfate). • If the metal is more reactive than the metal in the compound, it competes with the less reactive metal. The more reactive metal pushes out, or displaces,the less reactive metal from its compound. • If the metal is less reactive than the metal in the compound, it will not compete and so there is no reaction.

32. Displacement reactions – examples magnesium silver + + copper chloride magnesium chloride   magnesium chloride + copper The reactivity series can be used to predict if a metal will react with a metal compound. • Will magnesium react with copper chloride? Magnesium is a more reactive metal than copper, so magnesium displaces the copper from its compound. • Will silver react with magnesium chloride? no reaction Silver is a less reactive metal than magnesium, so silver does not displace the magnesium from its compound.

33. Displacement reactions – observation before after magnesium + copper sulfate  magnesium sulfate + copper This photograph shows what happens when magnesium reacts with copper sulfate. Why does the blue colour of the coppers sulfate solution gradually disappear during this reaction? Magnesium is a more reactive metal than copper and so the magnesium displaces the copper from the copper sulfate solution. This is why the blue colour disappears.

34. Displacement of sulfates – predictions Use the reactivity series to predict if there is a reaction when these metals are added to different metal sulfate solutions. metalsulfate solution metal              = displacement reaction = no reaction 

35. Displacement of sulfates – magnesium magnesium magnesium magnesium + + + copper sulfate zinc sulfate iron sulfate    Doesmagnesiumreactwithanddisplacethesemetalsulfates and if so what products are formed? magnesium sulfate + copper  magnesium sulfate + zinc  magnesium sulfate + iron 

36. Displacement of sulfates – zinc zinc zinc zinc + + + magnesium sulfate iron sulfate copper sulfate    Doeszincreactwithanddisplacethesemetalsulfates and if so what products are formed?  no reaction zinc sulfate + iron  zinc sulfate + copper 

37. Displacement of sulfates – iron iron iron iron + + + magnesium sulfate zinc sulfate copper sulfate    Doesironreactwithanddisplacethesemetalsulfates and if so what products are formed?  no reaction  no reaction iron sulfate + copper 

38. Displacement of sulfates – copper copper copper copper + + + zinc sulfate copper sulfate magnesium sulfate    Doescopperreactwithanddisplacethesemetalsulfates and if so what products are formed?  no reaction  no reaction  no reaction

39. Displacement of oxides aluminium + iron oxide  aluminium oxide + iron Displacement reactions can also occur between a metal and a metal compound that is a solid. The more reactive aluminium wins the oxygen from the less reactive iron. The reaction gets so hot that the iron melts! This is the Thermit reaction and is used to weld railway lines.

40. Displacement of oxides – predictions Use the reactivity series to predict if there is a reaction when each mixture of a metal and a metal oxide is heated. metal oxide metal        = displacement reaction = no reaction 

41. Displacement of oxides – zinc zinc zinc + + copper oxide iron oxide   Doeszincreactwithanddisplacethesemetaloxides and if so what products are formed? zinc oxide + copper  zinc oxide + iron  • Zinc is the more reactive than copper and iron.

42. Displacement of oxides – iron iron iron + + zinc oxide copper oxide   Doesironreactwithanddisplacethesemetaloxides and if so what products are formed?  no reaction iron oxide + copper  • Iron is less reactive than zinc but more reactive than copper.

43. Displacement of oxides – copper copper copper + + zinc oxide iron oxide   Doescopperreactwithanddisplacethesemetaloxides and if so what products are formed?  no reaction  no reaction • Copper is less reactive than zinc and iron and will not displace either of these metals.

44. Displacement reactions – activity Use the reactivity series to predict if each mixture will react. Reactants Reaction? potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold iron oxide magnesium  copper sulfate zinc  potassium hydrochloric acid   gold iron chloride  calcium sodium chloride calcium oxygen 

45. Displacement reactions – activity magnesium copper magnesium silver + + + + iron chloride zinc oxide gold nitrate aluminium oxide     Use the reactivity series to predict if each mixture will react and complete the word equation. magnesium oxide + aluminium magnesium chloride + iron no reaction copper nitrate + gold

46. Contents 9F Patterns of Reactivity Metals and water Metals and oxygen Metals and acid Reactivity series and displacement Summaryactivities

47. Glossary displaced metal – The metal that is pushed out of a compound by a more reactive metal. displacement –A reaction in which a more reactive metal replaces a less reactive metal in a compound. reactive –A substance that reacts quickly or easily. reactivity –How quickly or easily a substance will react. reactivity series –The list of metals placed in order of their reactivity starting with the most reactive. tarnished –A metal that has become dull after reacting with water and oxygen in the air. Thermit reaction –The displacement reaction between aluminium and iron oxide that is used to weld railway lines. unreactive –A substance that reacts very slowly or does not react at all.

48. Anagrams

49. True or false?

50. Multiple-choice quiz