1. 08/06/2016 Using Covalent Structures Form of carbon PropertyUsesWhy? Carbon – diamond Very hardDrill tipsExtremely strong covalent structure GraphiteSoft, conducts electricity Lubricants and making electrodes Graphite is arranged in layers that can slide over each other and it contains free electrons.

2. 08/06/2016 Separating Immiscible Liquids “Immiscible” means “two liquids that can’t be dissolved”, e.g. oil and water: Separating these liquids is fairly easy – you simply allow them to settle and then “tap off” the heavier liquid at the bottom using a separating funnel.

3. 08/06/2016 Separating miscible liquids Miscible liquids are liquids that have dissolved together, so separating them is much harder. Here’s an example – distillation: This apparatus can be used to separate water and ethanol because they have different _____ ______. The ______ will evaporate first, turn back into a _______ in the condenser and collect in the _______. The water remains in the round flask, as long as the _______ does not exceed 100 O C. Words – temperature, boiling points, ethanol, beaker, liquid

4. 08/06/2016 Fractional Distillation of Air Air can be distilled in the same way – you simply have to get it cold enough first: Liquefied air at -200 O C Gaseous nitrogen out at -190 O C Liquid oxygen out at -185 O C

5. 08/06/2016 R G B XChromatography Chromatography can be used to separate a mixture of different inks. Some example questions… 1 2 3 Z 1) Ink X contains two different colours. What are they? 2) Which ink is ink Z made out of?

6. 08/06/2016 R f value The Rf value is a way of measuring how far a substance has moved: R G B This line marks the distance travelled by the solvent R f value = Distance travelled by substance Distance travelled by solvent

7. 08/06/2016 Example questions Calculate the R f values of the following: R G B 10cm 2cm 8cm 5cm

8. 08/06/2016 Using Chromatography Chromatography can be used to test which foods contain which ingredients. For example, consider the dye Sudan 1, which was found in 450 foods in 2005. Which dye contains Sudan 1? Sudan 1 Dye 1 Dye 2 Dye 3

9. 08/06/2016 Topic 4 – Groups in the Periodic Table

10. 08/06/2016 HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Alkali metals (Group 1) Noble gases (Group 0) Halogens (Group 7) These elements are called the “transition metals” This line divides metals from non- metals

11. 08/06/2016 +++++ +++++ +++++ +++++ +++++ A closer look at metals + - + - + - + - + - + - + - + - +++ +++ ++ Delocalised electrons Metals are defined as elements that readily lose electrons to form positive ions. The electrons in the highest shells are delocalised and surround positive ions. There are a number of ways of drawing this:

12. 08/06/2016 Properties of metals Metals have very high melting points (which means that they are usually _____) whereas non-metals will melt at lower ___________ All metals conduct heat and __________ very well, whereas non-metals don ’ t (usually) Metals are strong and ______ but bendable. Non-metals are usually _____ or they will snap. Metals will _____ when freshly cut or scratched, whereas non-metals are usually dull. Metals have higher _______ than non-metals (i.e. they weigh more) Metals can be used to make ______ (a mixture of different metals) Words - alloys, electricity, solids, weak, densities, temperatures, tough, shine

13. 08/06/2016 The Transition Metals Some facts… 1) They are all ______ and solid (except _________) 2) They are ____ reactive than the alkali metals Words – hard, coloured, mercury, less, catalyst, insoluble 3) They can form __________ compounds, usually _______ 4) They can be used as a ______ (a chemical that speeds up a reaction)

14. 08/06/2016 Different forms of elements and compounds 1) Ionic, like sodium chloride: 2) Giant covalent structures, like graphite: 4) Simple covalent molecules, like methane: 3) Metallic, like iron: Cl - Na + Cl - Na + Cl - Na + Cl - Na + Cl - Na + Cl - Na + Elements and compounds can form many different structures, including: +++++ +++++ +++++ +++++ +++++ H H H H C

15. 08/06/2016 Different properties Using information from previous lessons, complete this table: Form of element/ compound ExampleDoes it conduct electricity? Relative melting and boiling points Solubility IonicSalt (sodium chloride) Yes when molten/ dissolved High Giant covalent Metallic Simple covalent

16. 08/06/2016 Group 1 – The alkali metals Li Na K Rb Cs Fr Watch video of these metals reacting with water (from Sky One’s Brainiac)

17. 08/06/2016 Group 1 – The alkali metals 1) These metals all have ___ electron in their outer shell. Some facts… 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: Words – down, one, shell, hydrogen, nucleus, decreases Potassium + water potassium hydroxide + hydrogen 2K (s) + 2H 2 O (l) 2KOH (aq) + H 2(g) 2) Density increases as you go down the group, while melting point ________

18. 08/06/2016 Trends in Group 1 Consider a sodium atom: Take away one of the electrons + + Now consider a potassium atom: Sodium ion Potassium ion Take away one of the electrons Potassium loses its electron more easily because its further away – potassium is MORE REACTIVE

19. 08/06/2016 Group 7 – The halogens F Cl Br I At

20. 08/06/2016 The Halogens - Chlorine Each molecule has a strong force holding the atoms together, but the forces between molecules are very weak so chlorine is a gas at room temperature and is pale yellow.

21. 08/06/2016 The Halogens - Bromine The forces between molecules are slightly stronger so bromine is a liquid at room temperature. It is reddish-brown in colour.

22. 08/06/2016 The Halogens - Iodine Iodine is a solid at room temperature but with gentle heating it will melt. The atoms will remain in pairs. In solid form iodine is grey like metal but gaseous iodine is purple.

23. 08/06/2016 The halogens – some reactions 1) Halogen + metal: Na + Cl - Na Cl + 2) Halogen + hydrogen: H Cl + H Halogen + metal metal halide Halogen + hydrogen a hydrogen halide This can be dissolved in water to form an acid

24. 08/06/2016 Trends in Group 7 Consider a fluorine atom: Add an electron - - Now consider a chlorine atom: Flouride ion Chloride ion Add an electron Chlorine doesn’t gain an electron as easily as fluorine so it is LESS REACTIVE

25. 08/06/2016 Displacement reactions To put it simply, a MORE reactive halogen will displace a LESS reactive halogen from a solution of its salt. F Cl Br I Decreasing reactivity Potassium chloride KCl (aq) Potassium bromide KBr (aq) Potassium iodide KI (aq) Chlorine Cl 2 Bromine Br 2 Iodine I 2

26. 08/06/2016 Group 0 – The Noble gases He Ne Ar Kr Xe Rn Questions: 1) How many electrons do these elements have in their outer shell? 2) How does this affect their reactivity?

27. 08/06/2016 How the Noble Gases were discovered Sir William Ramsay, 1852-1916 LiBeBCNOFNaMgAl A while ago we discussed the idea that Mendeleev left gaps in the periodic table to account for undiscovered elements: I discovered most of the Noble Gases around the year 1900. I did this by: 1)Noticing the density of nitrogen made in certain reactions differed from the density of nitrogen in air 2)I then developed a hypothesis about the existence of undiscovered elements 3)I then tested this hypothesis with further experiments. Ramsay’s blue plaque outside a house in Notting Hill

28. 08/06/2016 Group 0 – The Noble gases Some facts… 1)All of the noble gases have a full outer shell, so they are very ______ 2)They all have _____ melting and boiling points and are inflammable 3) They exist as single atoms rather then _________ molecules 4)Helium is ________ then air and is used in balloons and airships (as well as for talking in a silly voice) 5)Argon is used in light bulbs (because it is so unreactive) and argon, krypton and ____ are used in fancy lights Words – neon, stable, low, diatomic, lighter

29. 08/06/2016 Properties of the Noble Gases ElementMelting Point ( O C)Boiling Point ( O C)Density (g/dm 3 ) Helium-272-2690.1786 Neon-249-2460.9002 Argon-189-1861.784 Krypton-157-1533.749 Xenon??? What numbers would you expect Xenon to have?

30. 08/06/2016 Topic 5 – Chemical Reactions

31. 08/06/2016 Endothermic and exothermic reactions Step 1: Energy must be SUPPLIED to break bonds: Step 2: Energy is RELEASED when new bonds are made: A reaction is EXOTHERMIC if more energy is RELEASED then SUPPLIED. If more energy is SUPPLIED then is RELEASED then the reaction is ENDOTHERMIC Energy

32. 08/06/2016 Common examples of these reactions Are these reactions exothermic or endothermic? Burning Hand warmer packs Photosynthesis Cooling packs

33. 08/06/2016 Example reactions ReactionTemp. after mixing/ O CExothermic or endothermic? Sodium hydroxide + dilute hydrochloric acid Sodium hydrogencarbonate + citric acid Copper sulphate + magnesium powder Sulphuric acid + magnesium ribbon

34. 08/06/2016 Energy level diagrams Energy level Reaction progress Energy required to break bonds (endothermic) Energy given out making bonds (exothermic)

35. 08/06/2016 Exothermic vs endothermic: EXOTHERMIC – more energy is given out than is taken in (e.g. burning, respiration) ENDOTHERMIC – energy is taken in but not necessarily given out (e.g. photosynthesis)

36. 08/06/2016 Rates of Reaction Hi. I’m Mike Marble. I’m about to have some acid poured onto me. Let’s see what happens… Here comes an acid particle… It missed! Here comes another one. Look at how slow it’s going… No effect! It didn’t have enough energy! Oh no! Here comes another one and it’s got more energy…

37. 08/06/2016 Measuring the Rate of Reaction Two common methods:

38. 08/06/2016 Rates of Reaction Chemical reactions occur when different atoms or molecules _____ with each other but they HAVE to collide with enough _______. Basically, the more collisions we get and the more energetic they are the _______ the reaction goes. The rate at which the reaction happens depends on four things: 1)The _______ of the reactants, 2)Their concentration 3)Their surface area 4)The ______ the reactants are under Words – energy, quicker, pressure, temperature, collide

39. 08/06/2016 Catalysts Summary Words – surface area, speed up, used up, cheaper, monoxide Catalysts are used to ____ __ a reaction to increase the rate at which a product is made or to make a process ________. They are not normally ___ __ in a reaction. Cars use catalytic converters to remove unwanted gases. They take gases like carbon _______ and react them with water to form carbon dioxide. They have a large _____ ___ and work best at high temperatures. Carbon monoxide + oxygen carbon dioxide

40. 08/06/2016 Topic 6 – Quantitative Chemistry

41. 08/06/2016 Mass and atomic number revision ParticleRelative MassRelative Charge Proton1+1 Neutron10 ElectronVery small MASS NUMBER = number of protons + number of neutrons SYMBOL PROTON NUMBER = number of protons (obviously)

42. 08/06/2016 Relative formula mass, M r The relative formula mass of a compound is the relative atomic masses of all the elements in the compound added together. E.g. water H 2 O: Therefore M r for water = 16 + (2x1) = 18 Work out M r for the following compounds: 1)HCl 2)NaOH 3)MgCl 2 4)H 2 SO 4 5)K 2 CO 3 H=1, Cl=35 so M r = 36 Na=23, O=16, H=1 so M r = 40 Mg=24, Cl=35 so M r = 24+(2x35) = 94 H=1, S=32, O=16 so M r = (2x1)+32+(4x16) = 98 K=39, C=12, O=16 so M r = (2x39)+12+(3x16) = 138 Relative atomic mass of O = 16Relative atomic mass of H = 1

43. 08/06/2016 Empirical formulae Empirical formulae is simply a way of showing how many atoms are in a molecule (like a chemical formula). For example, CaO, CaCO 3, H 2 0 and KMnO 4 are all empirical formulae. Here’s how to work them out: A classic exam question: Find the simplest formula of 2.24g of iron reacting with 0.96g of oxygen. Step 1: Divide both masses by the relative atomic mass: For iron 2.24/56 = 0.04For oxygen 0.96/16 = 0.06 Step 2: Write this as a ratio and simplify: 0.04:0.06 is equivalent to 2:3 Step 3: Write the formula: 2 iron atoms for 3 oxygen atoms means the formula is Fe 2 O 3

44. 08/06/2016 Example questions 1)Find the empirical formula of magnesium oxide which contains 48g of magnesium and 32g of oxygen. 2)Find the empirical formula of a compound that contains 42g of nitrogen and 9g of hydrogen. 3)Find the empirical formula of a compound containing 20g of calcium, 6g of carbon and 24g of oxygen. MgO NH 3 CaCO 3

45. 08/06/2016 Calculating percentage mass If you can work out M r then this bit is easy… Calculate the percentage mass of magnesium in magnesium oxide, MgO: A r for magnesium = 24Ar for oxygen = 16 M r for magnesium oxide = 24 + 16 = 40 Therefore percentage mass = 24/40 x 100% = 60% Percentage mass (%) = Mass of element A r Relative formula mass M r x100% Calculate the percentage mass of the following: 1)Hydrogen in hydrochloric acid, HCl 2)Potassium in potassium chloride, KCl 3)Calcium in calcium chloride, CaCl 2 4)Oxygen in water, H 2 O 3% 52% 36% 89%

46. 08/06/2016 Recap questions Work out the relative formula mass of: 1)Carbon dioxide CO 2 2)Calcium oxide CaO 3)Methane CH 4 Work out the percentage mass of: 1)Carbon in carbon dioxide CO 2 2)Calcium in calcium oxide CaO 3)Hydrogen in methane CH 4 44 56 16 27% 71% 25%

47. 08/06/2016 Balancing equations Consider the following reaction: Na O HH HH O H Sodium + water sodium hydroxide + hydrogen + + This equation doesn’t balance – there are 2 hydrogen atoms on the left hand side (the “reactants” and 3 on the right hand side (the “products”)

48. 08/06/2016 Balancing equations We need to balance the equation: Na O HH HH O H Sodium + water sodium hydroxide + hydrogen + + Na O HH O H Now the equation is balanced, and we can write it as: 2Na (s) + 2H 2 O (l) 2NaOH (aq) + H 2(g)

49. 08/06/2016 Some examples Mg + O 2 Zn + HCl Fe + Cl 2 NaOH + HCl CH 4 + O 2 Ca + H 2 O NaOH + H 2 SO 4 CH 3 OH + O 2 MgO ZnCl 2 + H 2 FeCl 3 NaCl + H 2 O CO 2 + H 2 O Ca(OH) 2 + H 2 Na 2 SO 4 + H 2 O CO 2 + H 2 O 2 2 2 3 2 2 2 2 2 2 2 2 4

50. 08/06/2016 Calculating the mass of a product E.g. what mass of magnesium oxide is produced when 60g of magnesium is burned in air? Step 1: READ the equation: 2Mg + O 2 2MgO IGNORE the oxygen in step 2 – the question doesn’t ask for it Step 3: LEARN and APPLY the following 3 points: 1)48g of Mg makes 80g of MgO 2)1g of Mg makes 80/48 = 1.66g of MgO 3)60g of Mg makes 1.66 x 60 = 100g of MgO Step 2: WORK OUT the relative formula masses (M r ): 2Mg = 2 x 24 = 48 2MgO = 2 x (24+16) = 80

51. 08/06/2016 Work out M r : 2H 2 O = 2 x ((2x1)+16) = 36 2H 2 = 2x2 = 4 1.36g of water produces 4g of hydrogen 2.So 1g of water produces 4/36 = 0.11g of hydrogen 3.6g of water will produce (4/36) x 6 = 0.66g of hydrogen M r : 2Ca = 2x40 = 80 2CaO = 2 x (40+16) = 112 80g produces 112g so 10g produces (112/80) x 10 = 14g of CaO M r : 2Al 2 O 3 = 2x((2x27)+(3x16)) = 204 4Al = 4x27 = 108 204g produces 108g so 100g produces (108/204) x 100 = 52.9g of Al 2 O 3 1)When water is electrolysed it breaks down into hydrogen and oxygen: 2H 2 O 2H 2 + O 2 What mass of hydrogen is produced by the electrolysis of 6g of water? 3) What mass of aluminium is produced from 100g of aluminium oxide? 2Al 2 O 3 4Al + 3O 2 2) What mass of calcium oxide is produced when 10g of calcium burns? 2Ca + O 2 2CaO

52. 08/06/2016 Another method Try using this equation: Mass of product IN GRAMMES Mass of reactant IN GRAMMES M r of product M r of reactant Q. When water is electrolysed it breaks down into hydrogen and oxygen: 2H 2 O 2H 2 + O 2 What mass of hydrogen is produced by the electrolysis of 6g of water? Mass of product IN GRAMMES 6g 4 36 So mass of product = (4/36) x 6g = 0.66g of hydrogen

53. 08/06/2016 Problems with this technique Calculating the amount of a product may not always give you a reliable answer... 1)The reaction may not have completely _______ 2)The reaction may have been _______ 3)Some of the product may have been ____ 4)Some of the reactants may have produced other _______ The amount of product that is made is called the “____”. This number can be compared to the maximum theoretical amount as a percentage, called the “percentage yield”. Words – lost, yield, finished, reversible, products

54. 08/06/2016 Percentage Yield Percentage yield = actual yield (in g) theoretical yield Example question: Theoretical yield = the amount of product that should be made as calculated from the masses of atoms Actual yield = what was actually produced in a reaction 65g of zinc reacts with 73g of hydrochloric acid and produces 102g of zinc chloride. What is the percentage yield? Zn + 2HCl ZnCl 2 + H 2 The theoretical yield is 136g (using Cl = 35.5) so the % yield is 75%

55. 08/06/2016 Percentage yield Some example questions: 1)The predicted yield of an experiment to make salt was 10g. If 7g was made what is the percentage yield? 2)Dave is trying to make water. If he predicts to make 15g but only makes 2g what is the percentage yield? 3)Sarah performs an experiment and has a percentage yield of 33%. If she made 50g what was she predicted to make? Percentage yield = Actual yield Predicted yield X 100% 70% 13% 150g

56. 08/06/2016 Chemical Economics Hi. We’re industrial scientists and we want to make lots of chemicals and sell them to make money. What problems would we face? Possible problems with making chemicals: 1)Reactions often produce chemicals that aren’t commercially useful or that can’t be sold 2)Reactions can also produce chemicals that present environmental and social problems. Therefore we need reactions and processes that give us a high percentage yield where all of the products are useful and the reactions happen quickly.