1. C1 Revision

2. Topic 1 The fundamental ideas in chemistry

3. The periodic table of elements
Everything is made from elements
The periodic table of elements shows us metals (left) and non-metals (right)
Each element has a symbol… Sodium is ‘Na’ and Carbon is ‘C’
Each group has similar chemical properties

4. Atoms
A particle of an element is called an atom e.g. a carbon atom, a sodium atom
Atoms have the same amount of positive and negative charges so they are neutral
Type of sub-atomic particle
Relative charge
Proton
+1 (positive)
Neutron
0 (neutral)
Electron
-1 (negative)

5. Mass number Atomic number
Elements in the periodic table are arranged in order of their atomic number
atomic number = number of protons
No. of protons = no. of electrons (protons and electrons cancel each other’s charges out)
The mass number = no. of protons + neutrons
No. of neutrons = mass no. – atomic no.

6. Arrangement of electrons
Electrons are arranged around the nucleus of atoms in shells
The first shell can hold up to 2 atoms
The second shell can hold up to 8 atoms
The third shell can hold up to 8 atoms
Then the fourth shell fills up
Lithium
2,1

7. Arrangement of electrons
Fluorine
2,7
Chlorine
2,8,7
Calcium
2,8,8,2

8. Electrons and the periodic table
Elements in the same group all have the same number of electrons in their outer shell
This means that they share similar properties
Group 1 elements all have 1 electron in the outer shell – they are all very reactive
Group 0 elements (noble gases) have full outer shells – they are unreactive

9. Group 1 – alkali metals
Lithium, sodium and potassium all react violently with water
They form salts which are alkaline in pH
Lithium + water  lithium hydroxide + hydrogen
Sodium + water  sodium hydroxide + hydrogen
potassium + water  potassium hydroxide + hydrogen

10. Forming compounds
When atoms of different types of elements join together they form ‘compounds’
Sometimes atoms react by transferring electrons – this happens when metals react with non-metals and forms ions
Metals lose electrons and become positive ions (+)
Non-metals gain electrons – negative ions (-)
These ions are attracted to each other and form an ionic bond

11. Ionic bonds

12. Forming molecules
Sometimes atoms react by sharing electrons – this happens when non-metals react with non-metals
This is called covalent bonding

13. Chemical formulae
This tells us the number of atoms in a compound or molecule
CH4
H2O
MgCl2
CaCO3
Fe2O3
2C2H5OH
- 1 x Carbon, 4 x Hydrogen
- 2 x Hydrogen, 1 x Oxygen
- 1 x Magnesium, 2 x Chlorine
- 1 x Calcium, 1 x Carbon, 3 x Oxygen
- 2 x Iron, 3 x Oxygen
- 4 x Carbon, 11 x Hydrogen, 1 x Oxygen

14. calcium carbonate  calcium oxide + carbon dioxide
Chemical equations
These show us the reactants (the substances we start with) and the products (the substances made)
calcium carbonate  calcium oxide + carbon dioxide
CaCO3  CaO + CO2
The equation is balanced – the same number of atoms are going in and are coming out of the reaction
The total mass of the products formed in a reaction is equal to the total mass of the reactants

15. Topic 2 Limestone and building materials

16. Calcium carbonate  calcium oxide + carbon dioxide
Limestone
Limestone is a rock made mainly of calcium carbonate (CaCO3)
It was formed from the remains of animals millions of years ago and can be quarried
Limestone can be heated with clay to make cement
Cement is mixed with sand to make mortar
Cement is mixed with water, sand and crushed rock to produce concrete
Heating limestone breaks it down – this is thermal decomposition
Calcium carbonate  calcium oxide + carbon dioxide
CaCO3  CaO + CO2

17. Magnesium carbonate  magnesium oxide + carbon dioxide
Carbonates
Buildings made of limestone are damaged by acid rain
When this happens, carbon dioxide is given off
Carbon dioxide turns limewater cloudy
The carbonates of magnesium, copper, zinc, calcium and sodium can be thermally decomposed too
They always form a metal oxide and carbon dioxide
e.g.
Magnesium carbonate  magnesium oxide + carbon dioxide
MgCO3  MgO + CO2

18. Uses of calcium oxide
When limestone is thermally decomposed it produces calcium oxide
When calcium oxide is added to water it produces calcium hydroxide
Calcium hydroxide can be filtered to produce limewater
Calcium hydroxide is an alkali. It can be used to neutralise acids. It is used by farmers to neutralise acidic soil, and to neutralise acidic industrial gases.

19. Topic 3 Metals and their uses

20. Extracting metals Metals are found in the Earth’s crust
They are often chemically combined with other elements – this is called the ore
Whether it is worth extracting a metal depends on:
1. How easy it is to extract it from its ore How much metal the ore contains

21. Transition metals

22. Extracting metals electrolysis carbon reduction Other methods
The way we extract a metal depends on its place in the reactivity series
Most reactive
Least reactive
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
electrolysis
carbon reduction
Other methods

23. Carbon reduction
A more reactive metal will displace a less reactive metal from its compounds
Many metals combine with oxygen – carbon will also displace less reactive metals from their oxides when heated with them
Metal oxide + carbon  metal + carbon dioxide
Lead oxide + carbon  lead + carbon dioxide
2PbO + C  2Pb + CO2

24. Iron (III) oxide + carbon  iron + carbon dioxide
Iron ore contains iron combined with oxygen
Iron is extracted using carbon reduction
It is heated in a blast furnace
Iron (III) oxide + carbon  iron + carbon dioxide
Iron straight from the blast furnace still contains some impurities (it is about 96% iron) – it is very brittle and is called cast iron. It can be used to mould different shapes
Removing the impurities gives us pure iron – this is too soft for most uses

25. Iron To make iron useful we can add small amounts of other elements
A metal that is mixed with other elements is called an alloy
Steel is an alloy of iron
Carbon steel contains between 0.03% and 1.5% carbon
Low carbon steels are easily shaped
High carbon steels are very strong
Iron with chromium and nickel makes stainless steel

26. Aluminium Aluminium is a very low density metal
It can be alloyed with other elements to make it very strong
It cannot be extracted from its ore by carbon reduction because it is more reactive than carbon
It is extracted using electrolysis instead – an electric current is passed through molten aluminium oxide at high temperatures to break it down
Electrolysis is very expensive because lots of energy is needed – this is why we recycle aluminium

27. Titanium Titanium is very strong and has a very high melting point
It is used for jet engine parts, replacement hip joints and as nuclear reactor parts
It cannot be reduced using carbon because it is more reactive
It is reduced using sodium or magnesium, but this process is very complicated and has lots of steps, which means the titanium is very expensive

28. Copper (I) sulfide + oxygen  copper + sulphur dioxide
Pure copper is a good conductor of electricity, does not react with water and can be shaped easily
Copper can be removed from its ore by smelting
This involved heating it in a furnace:
Copper (I) sulfide + oxygen  copper + sulphur dioxide

29. Copper The copper produced is purified using electrolysis
This involves passing an electrical current through a copper solution

30. Copper Copper-rich ores are running out
New methods are used to extract copper from low grade ores
Phytomining – using plants to extract copper
Bioleaching – using bacteria to extract copper
20% of our copper comes from bioleaching

31. More alloys
Bronze = copper + tin this is tough with resistant to corrosion (used to make statues)
Brass = copper + zinc
this increases the strength of copper but is still malleable (used to make musical instruments)
Gold can be alloyed to increase its strength
There are over 300 aluminium alloys with different properties

32. Topic 4 Crude oil and fuels

33. Crude oil
Crude oil is a fossil fuel that was formed millions of years ago from the remains of sea creatures
It is a dark, thick liquid containing a mixture of lots of different chemical compounds
We separate the different compounds by fractional distillation
This involves separating the different fractions depending on their boiling points

34. Crude oil
Crude oil contains compounds made of only hydrogen and carbon – hydrocarbons
Most of the hydrocarbons are alkanes
The general formula for alkanes is CnH(2n+2)
Alkanes are saturated hydrocarbons because they are full – no more bonds can be made

35. Alkanes
Methane CH4
Ethane
C2H6
Propane
C3H8
Butane
C4H10

36. Properties of hydrocarbons
Chain length:
Boiling point:
Low
High
Volatility (tendency to turn into gas):
Viscosity (how easily it flows):
Low (very runny)
High (very thick)
Flammability (how easily it burns):

37. Fractional distillation of crude oil

38. Propane + oxygen  carbon dioxide + water C3H8 + 5O2  3CO2 + 4H2O
Combustion
When hydrocarbons are burned in air they release energy – this ‘oxidises’ the hydrogen and the carbon in the fuel (oxygen from the air is added)
This is called complete combustion
Propane + oxygen  carbon dioxide + water C3H8 + 5O2  3CO2 + 4H2O
The carbon dioxide released can cause global warming
Incomplete combustion happens when there is not enough oxygen – carbon monoxide (CO) is produced instead of carbon dioxide (CO2) – this is a poisonous gas

39. Pollution from hydrocarbons
Fossil fuels contain sulfur
When they are burned it releases sulfur dioxide
This is a poisonous gas that causes acid rain
High temperatures inside car engines can cause nitrogen and oxygen to react forming nitrogen oxides
These are poisonous and can trigger asthma and cause acid rain
Diesel engines can release particulates – these are tiny particles of carbon released into the air – these can cause global dimming

40. carbon monoxide + nitrogen oxides  carbon dioxide + nitrogen
Cleaner fuels
A catalytic converter can be fitted to a cars exhaust to reduce the amount of carbon monoxide and oxides of nitrogen released
carbon monoxide + nitrogen oxides  carbon dioxide + nitrogen
In power stations, sulfur dioxide can be removed from waste so it isn’t released into the atmosphere
Sulfur impurities can also be removed from fuels before combustion

41. Biofuels
Fossil fuels are running out – an alternative is biofuels made from plant or animal products
Biodiesel is made from oils from plants
It produces less pollution than diesel
Using land for biodiesel plants instead of food crops could cause problems
Ethanol is made from fermented sugar cane
Ethanol can be mixed with petrol to save money
Ethanol still gives off carbon dioxide when burned, but the sugar cane plant absorbs CO2 for photosynthesis

42. Topic 5 Other useful substances from crude oil

43. Cracking
After fractional distillation of crude oil, we are left with lots of less useful long-chain hydrocarbons
Long-chain hydrocarbons can be broken down in a process called cracking
This involves heating the fraction until it vapourises then passing it over steam or a hot catalyst

44. Hexane  butane + ethene
Cracking hexane
(800°C + hot catalyst)
Hexane  butane + ethene
C6H14  C4H10 + C2H4

45. Testing alkanes and alkenes
Bromine water reacts with alkenes and forms a colourless solution
Unsaturated hydrocarbon + bromine water  colourless solution
The double bond opens up and reacts
Bromine water remains orange in alkanes
Saturated hydrocarbon + bromine water  orange solution
The hydrocarbon cannot make any more bonds and doesn’t react

46. Polymers Hydrocarbon molecules can be used to make plastics
Small molecules are called monomers
Lots of monomers joined together make polymers

47. Polymerisation Chloroethene monomers
A section of poly chloroethene (PVC)

48. A repeating unit of poly chloroethene (PVC)
Polymers
A repeating unit of poly chloroethene (PVC)

49. New polymers New plastics with special properties are being developed
Dental fillings, waterproof fabrics and light sensitive plasters are made with special polymers
Smart polymers such as shape memory polymers ‘remember’ their original shape and will return to it when heated e.g. stitches closing a wound using body heat

50. Plastic waste
Many polymers are not biodegradable – this means microorganisms cannot break them down
New biodegradable polymers have been developed using starch and plant products that microorganisms can break down
This reduces the amount of plastics in landfills

51. Ethanol This is the type of alcohol found in alcoholic drinks
Its formula is C2H5OH
Ethanol can be made by fermentation of sugar from plants with yeast
Glucose (sugar)  ethanol + carbon dioxide C6H12O6  2C2H5OH + 2CO2
Ethanol can also be produced by reacting ethene (from cracking crude oil) with steam
A catalyst is used to speed up the reaction
Ethene + steam  ethanol
C2H4 + H2O  C2H5OH

52. Topic 6 Plant oils and their uses

53. Vegetable oil
Some fruits, seeds and nuts are rich in oils that can be extracted
The plant material is crushed and the oil is removed by pressing or distillation
Water and other impurities are removed
Vegetable oils provide nutrients and have a high energy content
They are important foods and can be used to make biofuels

54. Unsaturated oil + bromine water  colourless solution
Vegetable oil
Vegetable oils contain hydrocarbons
Unsaturated oils with C=C bonds can be detected using bromine water – they decolourise it
Unsaturated oil + bromine water  colourless solution
Vegetable oils have higher boiling points than water
Foods can be cooked at higher temperatures than by boiling
Food cooks faster and has different flavours
Food cooked in vegetable oil releases more energy when it is eaten (increased calorie content)

55. Emulsions Oil does not mix with water
An emulsifier is a special molecule that can be used to mix them and create an emulsion
Emulsions include ice cream and mayonnaise
Without an emulsifier, the oil and water would separate out into layers

56. Topic 7 Changes in the Earth and its atmosphere

57. Structure of the Earth The Earth is made up of many layers
Crust: thin and rocky
Mantle: flowing rock
Core: mixture of nickel and iron (inner core = solid outer core = liquid)
The Earth is made up of many layers
The Earth is surrounded by the atmosphere

58. Tectonic plates
The crust and mantle are broken up into large pieces (tectonic plates)
They move a few centimetres per year due to convection currents in the mantle
Earthquakes are caused when plate boundaries meet and push together

59. The modern atmosphere
The Earth’s atmosphere has been the same for about 200 million years

60. The early atmosphere There are lots of theories
One suggests that there was intense volcanic activity about 4.5 billion years ago when the Earth formed
This released carbon dioxide, water vapour and nitrogen gas – this formed the first atmosphere
The water vapour condensed and fell as rain, this formed the first oceans
When life evolved plants released oxygen
The amount of oxygen in the atmosphere increased and animals could evolve

61. Carbon
Most of the carbon dioxide from the Earth’s early atmosphere has been taken up by plants, which were eaten by animals, which were turned to sedimentary rocks
This means that most of the carbon is ‘locked’ in rocks and in fossil fuels
Carbon dioxide also dissolved in oceans
Over the past 200 million years the amount of carbon dioxide in the atmosphere has not changed much

62. The carbon cycle
Using fossil fuels is increasing the amount of carbon in the atmosphere again