Junior cycle science chemistry metals. By Theresa Lowry-Lehnen. Science Teacher.


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Junior cycle science chemistry metals. By Theresa Lowry-Lehnen. Science Teacher.

  1. 1. 07/03/14 Junior Cycle Science Chemistry Metals Theresa Lowry-Lehnen RGN, BSc (Hon’s) Nursing Science, PGCC, Dip Counselling, Dip Psychotherapy, BSc (Hon’s) Clinical Science, PGCE (QTS), H. Dip. Ed, MEd PhD student Health Psychology
  2. 2. Periodic table 07/03/14 The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Mendeleev Horizontal rows are called PERIODS
  3. 3. 07/03/14 What does the periodic table tell you? The SYMBOL of the element The NAME of the element The PROTON NUMBER of the element Au Gold 79
  4. 4. 07/03/14 Group 1 – The alkali metals Li Na K Rb Cs Fr
  5. 5. 07/03/14 Group 1 – The alkali metals Some facts… 1) These metals all have to be stored under ____ because they react with _______ 2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily. 3) They all react with water to form an alkali (hence their name) and __________, e.g: Potassium + water potassium hydroxide + hydrogen Words – down, oil, shell, hydrogen, nucleus, water
  6. 6. The Transition Metals 07/03/14 Some facts… 1) This section includes metals like gold, mercury, iron, copper 2) They are all ______ and solid (except _________) 3) They are ____ reactive than the alkali metals 4) They can form __________ compounds Words – hard, coloured, mercury, less
  7. 7. Some common symbols… 07/03/14 Lithium Li Copper Cu Sodium Na Zinc Zn Potassium K Aluminium Al Calcium Ca Gold Au Magnesium Mg Mercury Hg Iron Fe Fluorine F Oxygen O Chlorine Cl Nitrogen N Hydrogen H Sulphur S Helium He
  8. 8. 07/03/14 Reactions of metals with oxygen When a metal reacts with oxygen it will form a METAL OXIDE. This is what happens when a metal rusts. We can make this reaction happen quicker by burning the metal. METAL + OXYGEN METAL OXIDE Copy and complete the following reactions: 1) Magnesium + oxygen 2) Copper + oxygen 3) Calcium + oxygen 4) Iron + oxygen
  9. 9. 07/03/14 Reactions of metals with water When a metal reacts with water hydrogen is always given off. The other product will be either a metal hydroxide or a metal oxide. METAL + WATER METAL + WATER METAL OXIDE + HYDROGEN METAL HYDROXIDE + HYDROGEN Copy and complete the following reactions: 1) Sodium + water 2) Potassium + water 3) Calcium + water 4) Iron + steam
  10. 10. 07/03/14 Reactions of metals with acids When a metal reacts with an acid it gives off hydrogen (which can be “popped” using a lit splint). The other product is a salt. METAL + ACID e.g. magnesium + hydrochloric acid SALT + HYDROGEN magnesium chloride + hydrogen Copy and complete the following reactions: 1) Calcium + hydrochloric acid 2) Zinc + hydrochloric acid 3) Iron + hydrochloric acid 4) Lithium + sulphuric acid
  11. 11. 07/03/14 Complete the following reactions: 1) Lithium + water Lithium hydroxide + hydrogen 2) Lithium + hydrochloric acid Lithium chloride + hydrogen 3) Silver + oxygen Silver oxide 4) Magnesium + sulphuric acid Magnesium sulphate + hydrogen 5) Potassium + oxygen Potassium oxide 6) Aluminium + oxygen Aluminium oxide 7) Manganese + water Manganese oxide + hydrogen 8) Sodium + sulphuric acid Sodium sulphate + hydrogen 9) Lithium + oxygen Lithium oxide 10) Nickel + hydrochloric acid Nickel chloride + hydrogen
  12. 12. 07/03/14 An example question on reactivity Metal A B C D E Reaction with dilute acid Reaction with water Reaction with oxygen Some reaction Slow reaction Burns brightly No reaction No reaction Reacts slowly No reaction No reaction No reaction Violent reaction Slow reaction Burns brightly Reasonable reaction Reacts slowly Reacts with steam only
  13. 13. 07/03/14 The Reactivity Series Potassium Sodium Calcium Magnesium The Reactivity Series lists metals in order of reactivity: Aluminium Carbon Zinc Iron Lead Copper Silver Gold
  14. 14. Displacement reactions 07/03/14 A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound. Magnesium Copper sulphate Cu Mg The magnesium DISPLACES the copper from copper sulphate Mg SO4 Magnesium sulphate Cu Copper SO4
  15. 15. Displacement reactions 07/03/14 A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound. For example, if you drop some magnesium into copper sulphate a reaction will happen because magnesium is more reactive than copper, so the reaction is: Magnesium + copper sulphate copper + magnesium sulphate However, if you drop some copper into magnesium sulphate NOTHING will happen.
  16. 16. Some example reactions… Reaction Prediction 07/03/14 Observations Zinc + copper sulphate Zinc + lead nitrate Copper + lead nitrate Copper + silver nitrate Extension work – write down the equations for these reactions
  17. 17. Some example reactions… Reaction Prediction 07/03/14 Observations Zinc + copper sulphate Reaction DID happen Zinc + lead nitrate Reaction DID happen Copper + lead nitrate Reaction DID NOT happen Copper + silver nitrate Reaction DID happen Extension work – write down the equations for these reactions
  18. 18. Quiz on acids and alkalis Acid, alkali or both??? 1) This a pH of less than 7 2) This could kill cells 3) A metal hydroxide (e.g. sodium hydroxide) would be an _____ 4) When this reacts with a metal hydrogen is released 5) A metal carbonate (e.g. calcium carbonate) would be an _____ 6) This would feel soapy on your skin 7) This could be a corrosive 8) This will turn universal indicator purple 9) This would taste sour 10) This means “a base that can be dissolved” 07/03/14
  19. 19. Neutralisation reactions 07/03/14 When acids and alkalis react together they will NEUTRALISE each other. Neutralisation is an example of a displacement reaction: Sodium hydroxide Na Hydrochloric acid H OH The sodium DISPLACES the hydrogen from HCl Na Cl Sodium chloride H 2O Water Cl
  20. 20. Neutralisation experiment 07/03/14 In this experiment we mixed sodium hydroxide (an _____) and hydrochloric acid together and they ________ each other. The equation for this reaction is… Sodium hydroxide + hydrochloric acid sodium chloride + water A ____ was formed during the reaction, and we could have separated this by __________ the solution. The salt that we formed depended on the acid: •Hydrochloric acid will make a CHLORIDE •Nitric acid will make a _________ •Sulphuric acid will make a _________ Words to use – nitrate, neutralised, alkali, sulphate, salt, evaporating
  21. 21. Making salts 07/03/14 Whenever an acid and alkali neutralise each other we are left with a salt, like a chloride or a sulphate. Complete the following table: Hydrochloric acid Sodium hydroxide Potassium hydroxide Calcium hydroxide Sulphuric acid Nitric acid Sodium chloride + water Potassium sulphate + water Calcium nitrate + water
  22. 22. Salts of transition metals 07/03/14 These are the TRANSITION METALS – if we make a salt using a base made from one of these metals the procedure is different… 1) Drop the base into the acid… 2) Filter it to remove any leftover base 3) Evaporate it to get the salt
  23. 23. Extracting Metals 07/03/14 Some definitions: A METAL ORE is a mineral or mixture of minerals from which it is “economically viable” to extract some metal. Most ores contain METAL OXIDES (e.g. rust = iron oxide). To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction.
  24. 24. How do we do it? 07/03/14 Potassium Sodium Calcium Magnesium Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS Aluminium Carbon Zinc Iron Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE Tin Lead Copper Silver Gold Platinum These LOW REACTIVITY metals blatantly won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide
  25. 25. Extracting metals 1) What is an ore? 2) In what form are metals usually found in the Earth? 3) How do you get a metal out of a metal oxide? 4) What is this type of reaction called? Type of metal High reactivity (i.e anything above carbon) Middle reactivity (i.e. anything below carbon) Low reactivity Extraction process Examples 07/03/14
  26. 26. The Blast Furnace 07/03/14 1) HAEMATITE (iron ore), limestone and coke (carbon) are fed in here 2) Hot air is blasted in here 3) The carbon reacts with oxygen from the air to form carbon dioxide. 4) The carbon dioxide reacts with more carbon to form carbon monoxide 6) Molten slag (waste) is tapped off here Iron oxide + carbon monoxide 5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here iron + carbon dioxide
  27. 27. Electrolysis 07/03/14 Molecule of solid copper chloride Molecule of solid copper chloride after being dissolved Chloride ion Copper ion
  28. 28. Electrolysis 07/03/14 Electrolysis is used to extract a HIGHLY REACTIVE metal. When we electrolysed copper chloride the negative chloride ions moved to the positive electrode and the positive copper ions moved to the negative electrode – OPPOSITES ATTRACT!!! = chloride ion = copper ion
  29. 29. Redox reactions 07/03/14 These happen during electrolysis: At the positive electrode the negative ions LOSE electrons to become neutral – this is OXIDATION At the negative electrode the positive ions GAIN electrons to become neutral – this is REDUCTION These two processes are called REDOX REACTIONS OILRIG – Oxidation Is Loss of electrons Reduction Is Gain of electrons
  30. 30. 07/03/14 Purifying Aluminium Aluminium has to be extracted from its ore (called ________) by electrolysis. This is because aluminium is very ___________. The ore is mixed with cryolite to lower its ________ ________. The ore is then melted so that the ions can ______. The positively charged aluminium ions gather at the ___________ electrode. Oxygen forms at the positive electrode and causes it to wear away, which means that they have to be __________ frequently. Words – melting point, replaced, negative, bauxite, reactive, move
  31. 31. Rusting Experiment RUST NO RUST – no water 07/03/14 NO RUST – no oxygen
  32. 32. Rusting 07/03/14 Rust is formed when iron reacts with water AND oxygen. It’s an example of an oxidation reaction which can be sped up using salt. There are several ways of dealing with rust: 1) Regular painting or oiling 2) Galvanising – this is when iron objects are coated with zinc 3) Making objects out of a non-rusting metal, such as stainless steel 4) Attaching zinc bars to ships – the water will react with the zinc before it reacts with the iron, because zinc is more reactive