1. So what’s in air? Oxygen. Nitrogen. Carbon dioxide. Water vapour
Argon.
Other gases.
But how much of each?

2. The ones you need to know: Nitrogen 78%, Oxygen 21% and Argon 1%.

3. How good is this particle diagram?
Air is a mixture of different gases consisting of small molecules with large spaces between them.
What about the amount of each type of gas?

4. Evolution of Earth’s atmosphere.
Discover
1. Name the 4 gases that made up Earth’s early atmosphere?
2. Where did these gases come from?
3. Why did the oceans form?
4. Where did the first living things form?
5. What gas did they produce?
6. What is this process called?
7. How was carbon dioxide removed from the atmosphere?
8. Why was the formation of ozone important?
9. How was ammonia converted into nitrogen?
10. How long as our present atmosphere existed?

5. Evolution of Earth’s atmosphere.
1. Carbon dioxide, ammonia, steam and methane.
2. From the Earth’s crust (volcanoes).
3. Earth cooled down and steam condensed.
4. In the ocean.
5. Oxygen.
6. Photosynthesis.
7. Photosynthesis which then formed fossil fuels and by dissolving in the oceans and then forming sedimentary rocks.
8. It stops harmful rays form the Sun reaching the surface.
9. Reacted with oxygen and bacteria in the soil.
million years.
The answers in bold you definitely need to know!

6. Evolution of the Earth’s Atmosphere
Carbon
dioxide
Methane
Ammonia
Oxygen
Nitrogen
Others
Present day atmosphere contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO2
4 Billion years
3 Billion years
2 Billion years
1 Billion years
Present day

7. Evolution of the Earth’s Atmosphere
Volcanic activity releases CO2, methane, ammonia and water vapour into the atmosphere. The water vapour condenses to form oceans.
Some of the oxygen is converted into ozone. The ozone layer blocks out harmful ultra-violet rays which allows for the development of new life.
4 Billion years
3 Billion years
2 Billion years
1 Billion years
Present day
Green plants evolve which take in CO2 and give out oxygen. Carbon from CO2 becomes locked up in sedimentary rocks as carbonates and fossil fuels. Methane and ammonia react with the oxygen and nitrogen is released. Nitrogen is also produced as a result of denitrifying bacteria on nitrates from decaying plants.

8. What happens to the carbon dioxide?
1. Plants use it during photosynthesis.
Millions of years.

9. What happens to the carbon dioxide?
2. Dissolved in rain water and the sea.

10. What do you know about oxygen?

11. Element, mixture or compound?
Oxygen can be obtained from the atmosphere by separating it from the other gases.

12. Oxygen Production Plants

13. Getting oxygen from the atmosphere.
Air is filtered to remove dust, and then cooled in stages until it reaches –200°C. At this temperature it is a liquid. We say that the air has been liquefied.
Here's what happens as the air liquefies:
water vapour condenses, and is removed using absorbent filters
carbon dioxide freezes at –79ºC, and is removed
oxygen liquefies at –183ºC
nitrogen liquefies at –196ºC
The liquid nitrogen and oxygen are then separated by fractional distillation.
Liquid oxygen

14. Testing for oxygen.
How would you test a gas to find out if it is oxygen?

15. Oxy-fuel welding torches.
These welding torches use pure oxygen.
Why?

16. Other uses of oxygen.

17. The metal joins with oxygen
Copper
Copper oxide
To make a solid metal oxide
The metal gets heavier after combustion because the oxygen particles have joined with the metal particles to make a compound.

18. Oxidation – adding oxygen.
When a substance chemically combines with oxygen this is an example of an oxidation reaction.
Heating magnesium to make
magnesium oxide.

19. Fuels. What is a fuel? A substance that contains energy.
Why are fuels burned?
To release the energy.
What is the name of this type of reaction?
Combustion.

20. So what is in a fuel? Coal contains carbon.
Oil and gas are compounds called hydrocarbons.
From the name what are the 2 elements found in a hydrocarbon?
Hydrogen and carbon.
A hydrocarbon is a compound that contains hydrogen and carbon only.

21. Hydrocarbons.

22. Investigating the products of combustion.
What tests are being carried out to identify
the products of combustion?
What happens to the mass of the candle?

23. Complete combustion Hydrocarbon + oxygen  water + carbon dioxide
Methane + oxygen  water + carbon
CH4 + O2  CO2 + H2O
Balanced:
CH4 + 2O2  CO2 + 2H2O
Explain why combustion reactions are an example of an oxidation reaction?

24. To make gaseous products.
Non-metal fuels
join with oxygen
This is butane
To make gaseous products.
The mass of the fuel decreases because the products are gases that diffuse away.

25. Element or compound? B C D E A
1Label these substances as elements or compounds. carbon dioxide copper chloride zinc sodium hydrogen carbonate hydrogen 2 Label these particle pictures as elements or compounds. B C D E A
3 Label these formulae as elements or compounds.
CO2 CO
O2 NaCl
H2SO4 Cs
4 Which particle pictures show molecules?
5 Which particle picture is both an element and a molecule?

26. The formula of a compound shows the symbols of the elements it is made from and how many atoms of each element there are.
H2O
hydrogen
2 atoms
oxygen
1 atom
Formulas show all the atoms in a molecule.
NaCl
1 sodium atom
for every 1 chlorine atom or
the ratio of atoms

27. Understanding formulae
Draw particle diagrams for the following compounds; carbon dioxide CO2, carbon monoxide CO, sulfur dioxide SO2,
nitrogen monoxide NO, nitrogen dioxide NO2 and water H2O.
The first one has been drawn for you. O C O

28. Counting atoms.
Could you draw a particle picture of this compound?

29. When a compound is made from two elements.
Lithium
Calcium
The first part of the name is the name of the metal element.
The non-metal element makes the last part of the name.
oxide
chloride

30. Name of element when in a compound Compound names that end in –ate
Pyrotechnics Skycolour 3 Illuminate
SS6
Naming compounds
The first part of the name is the name of the metal element.
Metal element
Non-metal element
Compound
potassium
chlorine
magnesium
oxygen
sulfur
iron sulfide
sodium
sodium iodide
copper bromide
sodium fluoride
sodium
fluorine
The non-metal element makes up the last part of the name. But the ending of the non-metal element is changed to – ide.
Complete the tables:
Non-metal element
Name of element when in a compound
fluorine
fluoride
chlorine
chloride
oxide
sulfur
bromide
iodine
phosphide
Compound names that end in –ate
Contain two elements and oxygen
silver
nitrogen
oxygen
silver nitrate
Compound
Elements
calcium carbonate
calcium
carbon
oxygen
copper sulphate
potassium phosphate 30

31. Investigation – Iron and sulfur.
Mix the iron and sulfur together. Describe what it looks like.
Using the equipment provided – how can you separate this mixture?
Mix the iron and sulfur together – now heat it for 5 mins.
Let the substance cool down and then test to see if it is magnetic.
What is the name of the compound you have made?

32. iron particles Key: one iron particle
strong bonds between iron particles
iron particles held together by strong bonds

33. iron particles iron particles are attracted to a magnet
iron particles diagram

34. sulfur particles one sulfur particle
Key:
one sulfur particle
strong bonds between sulfur particles
sulfur particles held together by strong bonds

35. sulfur particles sulfur particles are not attracted to a magnet
sulfur particles diagram

36. iron particles
sulfur particles

37. A mixture of iron and sulfur particles
What’s this?
A mixture of iron and sulfur particles
strong bonds between iron particles
strong bonds between sulfur particles

38. A mixture of iron and sulfur particles
A magnet attracts the iron particles
but not the sulfur particles.
The mixture is separated
mixture diagram

39. A compound between iron and sulfur particles
What’s this?
A compound between iron and sulfur particles
one iron particle
one sulfur particle
strong bonds between iron and sulfur particles

40. A compound between iron and sulfur particles
strong bonds between iron and sulfur particles
The magnet cannot separate iron and sulfur particles in a compound
compound diagram

41. Conclusion:
After a chemical reaction has taken place the properties of the reactants and products are different.
Reactants (before)
Product (after)
Iron + sulfur  iron sulfide

42. Word equations
Rules
Reactants (starting materials) are on the left-hand side.
Products (what is made) are on the right-hand side.
An arrow  separates products from the reactants.
The + sign is used instead of ‘and’.

43. Testing understanding.
Write word equations for the 3 reactions described below.
1. Magnesium metal burns in oxygen gas with a bright white light to make a white powder called magnesium oxide.
2. A solution of sodium iodide is added to a solution of potassium nitrate to make a potassium iodide precipitate and a sodium nitrate solution.
3. Gaseous hydrogen and gaseous oxygen react explosively to form water vapor.

44. Answers 1. Magnesium + oxygen  magnesium oxide
2. Sodium iodide + potassium nitrate  potassium iodide +
sodium nitrate
3. Hydrogen + oxygen  water
What is the correct name for water?
Which 3 atoms are found in sodium nitrate?

45. Chemical reactions.
During a chemical reaction no new atoms are added and none are lost they are simply rearranged.

46. Writing balanced symbol equations.
1. The number of each type of atom must be equal for each side of the reaction.
2. The formula can’t be changed e.g. CO2 is always CO2
3. Only the number in front of the formula can change.

47. Complete combustion Hydrocarbon + oxygen  water + carbon dioxide
Methane + oxygen  water + carbon
CH4 + O2  CO2 + H2O
Balanced:
CH4 + 2O2  CO2 + 2H2O

48. Another example!

49. 2
Mg + O2  MgO 2 
Symbols Mg + O2

50. 2
Al I2  AlI3 3 1½ 2 
Symbols Al + I2

51. Some examples 2 2 3 2 3 Mg + O2 Zn + HCl Fe + Cl2 NaOH + HCl CH4 + O2
Mg O2
Zn HCl
Fe Cl2
NaOH HCl
CH O2
Ca H2O
NaOH H2SO4
CH3OH O2
MgO
ZnCl H2
FeCl3
NaCl H2O
CO H2O
Ca(OH) H2
Na2SO H2O 2

52. Are humans to blame for pollution?
Human activity
Natural processes

53. What is a pollutant? Pollutants are directly harmful to humans,
and some that are harmful to the environment and so cause harm to humans indirectly.
Can you give examples of both?

54. Some sources of pollution.

55. Pollutants. The common pollutants found in air are:
1. Carbon monoxide.
2. Oxides of nitrogen.
3. Sulfur dioxide.
4. Particulates of carbon.
1. Carbon dioxide indirectly harms us.
Checking exhaust emissions

57. Carbon monoxide.
Causes – incomplete combustion of petrol or diesel (hydrocarbons) in car engines.
Effect – a poisonous gas.

58. Carbon monoxide and volume of traffic.
What is the connection between amount of traffic and the concentration of carbon monoxide?

59. Oxides of nitrogen. Causes – formed in the internal combustion engine.
Effect – photochemical smog and acid rain.

60. Emissions of Nitrous oxides

61. Sulfur dioxide
Causes – formed when sulfur impurities in fossil fuels burn. Found in coal which is used in power stations.
Effects – acid rain kills plants, aquatic life, erode stonework and corrode metals.

62. Emissions of sulfur
dioxide.
How does this compare
with the map for
Nitrous oxides?

63. Formation of acid rain.

64. Effects of acid rain

65. Particulates of carbon.
Particulate carbon is deposited on surfaces, making them dirty.

66. What happens to the carbon dioxide?
1. Carbon dioxide is used by plants in photosynthesis. 2. Carbon dioxide dissolves in rain water and in sea water.

67. What fuels do power stations use?
The 3 fossil fuels are;
Coal
Oil
Gas
What pollutants do they produce?

68. Pollutants produced by power stations
The pollutants are:
1. Sulfur dioxide.
2. Particulates of carbon.
3. Carbon monoxide
1. Carbon dioxide indirectly harms us.

69. Reducing pollutants from power stations.
Remove sulfur dioxide and carbon from flue gas emissions.
Use less electricity.
Remove sulfur from natural gas and fuel oil.

70. Incomplete combustion.
Incomplete combustion occurs when there is not enough oxygen.
What would you observe if incomplete combustion is taking place?

71. Understanding incomplete combustion.
Which balanced equation represents complete combustion and which represents incomplete combustion?
What do you notice about the amount of oxygen in each reaction? 1 2

73. Neutralising the acidic gas.
When wet scrubbing with a Ca(OH)2 (lime) slurry, the reaction also produces CaSO3 (calcium sulfite ) and can be expressed as:
Ca(OH)2 + SO2 → CaSO3 + H2O
Alkali
Acid
Salt
Water

74. Seawater absorbs sulfur dioxide.
A natural alkaline usable to absorb SO2 is seawater. The SO2 is absorbed in the water, and when oxygen is added reacts to form sulfate ions SO4- and free H+

75. What pollutants are produced by a car engine?
The pollutants are:
1. Carbon monoxide.
2. Oxides of nitrogen.
3. Sulfur dioxide.
4. Particulates of carbon.
1. Carbon dioxide indirectly harms us.

76. Formation of Nitrogen Oxides
Nitrogen monoxide NO is formed during the combustion of fuels in air and is subsequently oxidised to nitrogen dioxide NO2 .
What type of reaction is this?
Oxidation – oxygen is added.

77. What happens to the nitrogen oxides?

78. Reducing pollutants from car emissions.
More efficient engines.
More public transport.
Use catalytic convertors.
Remove sulfur from fuel.
Legal limits on car
Emissions – checked by MOT tests.

79. Financial incentives:
Task:
Read p.53 Foundation or p.61 Higher of textbook.
What are the 3 ways that the UK government has used to encourage people to produce less pollution.
Then answer Q.2

80. Catalytic converter

81. What does a catalytic converter do?
After
Before
What happens to the carbon monoxide (CO) and nitrogen oxides (NOx )? Hint – oxidation/reduction.

82. What does a catalytic converter do?
A catalytic converter oxidises carbon monoxide into carbon dioxide.
It also reduces nitrogen oxide into nitrogen and oxygen.

83. What happens inside the converter.
2NO => N2 + O2 or 2NO2 => N2 + 2O2
This is a reduction reaction.
The reduction catalyst is the first stage of the catalytic converter.
The oxidation catalyst is the second stage of the catalytic converter.
2CO + O2 => 2CO2
This is an oxidation reaction.

84. Biofuels.
What are the problems and benefits of using biofuels as an alternative to petrol and diesel?
Have a go at the update activity.

85. Electric cars – as an alternative.
What are the problems and benefits of using electricity as an alternative to petrol and diesel?
Hint – think about how the electricity might be generated.

86. Is there a pattern when hay fever occurs?
Discover.
You will analyse some data in order to answer the question above.
The key skill you will use is;
Examine patterns and relationships.

87. Describe any pattern in the data?
Why would a graph be useful?
Why has the investigation being repeated?

88. What does correlation mean?
Correlation measures how strong is the link between the factor and the outcome.
Which of the graphs opposite shows the strongest link – greatest correlation?
How did you tell?

89. Strong correlation.

90. Be very careful!
Not all links between factor and outcome means one causes the other.

91. What do you need? The key to any correlation is the EVIDENCE.
If the evidence is good and links the factor to the outcome then a strong scientific claim can be made.

92. A reliable claim.
This evidence must be checked by other scientists – repeated – making it reliable