1. Module C5

2. What Types of Chemicals are there in the earth’s atmosphere?

3. The Earth is the source of all our materials.
Chemicals from the Earth’s spheres
The Earth is the source of all our materials.
We can get things from:
the atmosphere
the lithosphere
the hydrosphere

4. The Earth’s Spheres……..
We can break down the part of the Earth where we live and move into 4 areas, we call them spheres.
Lithosphere
Hydrosphere
Atmosphere

5. Lithosphere Made up of Crust & part of Mantle About 80km in depth.
Broken into tectonic plates which are moving.
Made up:
Silicates (compounds of Silicon & Oxygen)
Hydrocarbons (compounds of Hydrogen & Carbon)
Carbonates (such as chalk, limestone and sea shells)
Metal ores

6. Hydrosphere
The hydrosphere contains all the solid, liquid, and gaseous water of the planet.
97% of water is salty
It ranges from 10 to 20 kilometers in thickness.
Made up of:
Water
Dissolved oxygen
Dissolved nitrogen
Dissolved salts – Sodium Chloride
Calcium Carbonates (sea shells)

7. Atmosphere It envelope all air that surrounds the whole Earth.
It ranges up to 10,000km above the Crust.
Protects us from UV radiation from the Sun.
Made up of:
Nitrogen
Oxygen
Carbon dioxide
Water vapour
Noble gases – Argon.

8. What molecules are there in the atmosphere?
Pollutants?
Carbon dioxide
Formula?
Water vapour
Formula?
What do these substances have in common?
Bpt?
State at room temp?
Structure?
Type of chemical element?
Bonding?
The atmosphere
Nitrogen.
Formula?
Oxygen
Formula?
Inert Gases.
Formula?

9. Covalent Bonds When Non-metals combine they share electrons. i.e. H2
Hydrogen needs 1 electron (it has one possible bond).
So 2 hydrogen atoms will share there electrons with each other.
The Molecule is now held together by electrostatic forces between nuclei & electrons.
They can’t move any closer because there similar charged nuclei would repel.

10. Strong & Weak Bonding Strong Bonding
The forces inside the molecules holding the atoms together are many times stronger than the weak interaction between molecules.
So a very high temperature is needed to break apart an Oxygen molecule (O2).
The bonds that hold the compounds and molecules in the atmosphere are called Covalent Bonds. In Greek:
“Co” means together
“Valentia” means strong

11. Strong & Weak Bonding Weak Bonding
There is an attractive force between all molecules and compounds, but this is very weak.
We can think of the molecules moving in the atmosphere very quickly, so quickly that when they collide this attractive force is still too small to let them join up.
As we reduce the temperature there is more chance they will join together.
Watch the animation below, but remember that the boiling point of water is 100oC and Carbon dioxide is -78oC)
Animation

12. Attractive forces between molecules are weak.
Small molecules are gases or liquids at room temperature.

13. A line between element symbols to show a covalent bond.
H—H
hydrogen, H2
O O
oxygen, O2
N N
nitrogen, N2
O H H
water, H2O
O C O
carbon dioxide, CO2
A line between element symbols to show a covalent bond. H
H—C—H
methane, CH4
H H      
H—C—C—O—H
ethanol, C2H5OH

14. molecular formula
3D ball-and-stick model
2D displayed formula with lines for covalent bonds
3D space-filling model
Chemists have different ways of describing molecules.

15. Is there a correlation between Bpt, Structure and rfm?
Formula
Bpt degrees C
Structure
rfm
CO2
-78
Molecular 44 CO
-191 28 O2
-183 32
SO2
-10 64
C - diamond
Giant 12
What is the correlation between structure and boiling point?
Why do molecular substances have a lower boiling point then giant structures?
What is the correlation between rfm and boiling point for molecular structures?
Would water fit this pattern? Explain.
Explain why you think that water shows anomalous ( out of character )behaviour.

16. Covalent bonding
Hydrogen H2

17. Covalent Bonding……………
Fluorine – F2
Chlorine – Cl2

18. Summarising Covalent Bonds.
Covalent bonds share a pair of electrons that holds two atoms together.
Covalent bonds are strong.
They also have a definite direction so that molecules have a specific shape.

19. Summary
Our atmosphere is a relatively thin layer of air that surrounds the Earth
Dry air is a mixture of chemicals such as N2, O2, and Ar, which are elements and CO2, which is a compound
These chemicals have low boiling points which means they are gases over the range of temperatures found on the Earth.
Harmful gases that are added to the atmosphere by human activity are called pollutants
All the chemicals that make up our atmosphere are gases because they are made up of small molecules.
Small molecules are made up of atoms of one or more non-metal elements.
The atoms in the molecules are held together by strong covalent bonding.
The attractive forces between molecules are weak so they have low boiling points and are gases at normal temperatures.

20. Physical properties of chemicals in the spheres……
Describe the physical properties of the chemicals found in the:
Lithosphere.
Atmosphere.
Hydrosphere.
Describe solubility, melting points – high or low, and physical state at room temperature.
Explain why these properties link to the presence of the chemicals in each sphere.

21. What Reactions Happen in the Hydrosphere?

22. Salt harvesters in Thailand raking salt into piles

23. Ionic Salt crystals - NaCl
Crystals of sodium chloride
A sodium chloride crystal is made up of millions of Na+ and Cl– ions arranged in a regular pattern.
The regular pattern is responsible for the cubic range of all sodium chloride crystals.

24. What happens when water dissolves an ionic salt?+
Polar ( Charged) water molecules pull individual ions from the ionic crystal
The ions can move independently, so a solution of NaCl in water conducts electricity.

25. Crystals of sodium chloride
A sodium chloride crystal is made up of millions of Na+ and Cl– ions arranged in a regular pattern called a crystal lattice.
The lattice is responsible for the cubic shape of all sodium chloride crystals.

26. Physical Properties of Sodium Chloride
Oppositely charged ions attract each other.
Each ion will attract oppositely charged ions from all directions.
Each of these ions will in turn attract more ions.
A giant ionic lattice, made up of millions of ions, is built up and forms a sodium chloride crystal.
Physical properties:
High Mpt/Bpt...Why?
Electrical Conductivity Solid?
Electrical Conductivity in aqueous solution?

27. Are all Ionic Salts Soluble?
What Happens when Lead Nitrate reacts with Potassium Iodide?
Soluble
Soluble
Pb( NO3)2 (aq) + K I(aq)
Pb(I)2(ppt) + KNO3(aq)
Soluble
Insoluble - ppt

28. Precipitates and Predicting if one will form!
Precipitates form when an insoluble salt in formed during a reaction.
Ion
Soluble?
Insoluble ppts
Nitrate ( NO3)
All
None
Chloride ( Cl-1)
Mostly
Ag and Pb Chlorides
Sulphate ( SO4-2)
Ba and Pb sulphates
Carbonates ( CO3-2)
Only Na and Potassium Carbonates
Mainly

29. Predict and Apply!!!! Reactant 1 Reactant 2 Products PPt? Lead Nitrate
Barium Chloride
Sodium Nitrate
Copper Sulphate

30. Predict!!!! Answers Reactant 1 Reactant 2 Products PPt? Lead Nitrate
Barium Chloride
Yes – Lead Chloride
Sodium Nitrate No
Copper Sulphate
Yes – Barium Sulphate
Yes – Lead Sulphate

31. Testing for Positive and Negctive Ions in Ionic Salts
Ions such as chlorine, fluorine, calcium and sulfate are tested for to check they are within allowed limits.
Metal and non metal ions give characteristic reactions with reagents so that they can be identified.

32. Testing for positive ions
hydroxide ions in sodium hydroxide test solution OH-(aq)
Foe example,Calcium ions have a positive charge. They form a precipitate when mixed with sodium hydroxide.
The amount of precipitate indicates the amount of calcium in the water sample.
calcium ions in water sample Ca2+(aq)
Andrew Lambert Photography/Science Photo Library
calcium hydroxide precipitate Ca(OH)2(s)

33. Positive Ions Test Reaction with NaOH
Name of Ion
Observed colour : Product?
Iron(II), Fe2+
green precipitate
Iron(III), Fe3+
red-brown precipitate
Copper(II),Cu2+
light blue precipitate
Calcium, Ca2+
white precipitate
Zinc , Zn2+
white precipitate dissolves in excess sodium hydroxide solution
These positive metal ions form insoluble metal hydroxides with a characteristic colour

34. Testing for negative ions
barium ions in barium chloride test solution Ba2+(aq)
For example, sulphate ions have a negative charge. They form a precipitate when mixed with barium chloride.
The amount of precipitate indicates the amount of Sulphate in the water sample.
sulfate ions in water sample SO42-(aq)
Charles D. Winters/Science Photo Library
barium sulfate precipitate BaSO4(s)

35. Negative Non Metal Ion Tests
Name of Ion and formulae
Observed colour : Product?
Negative ion solution
Result of test for ion
chloride, Cl
white precipitate with silver nitrate
bromide, Br
cream precipitate with silver nitrate
iodide, I
yellow precipitate with silver nitrate
sulfate, SO42
white precipitate with barium Sulphate
carbonate, CO32
Bubbles of CO2 gas; limewater turns cloudy with HCl and limewater
These negative non metal ions form insoluble solids when reacted with another chemical reagent such as silver nitrate

36. What types of chemicals make up the Earth’s Lithosphere?

37. Giant Covalent Structures…….
Diamond – C.
Graphite – C.
Quartz – SiO2

38. Structure of diamond and Graphite.
Explain why diamond has a high melting point
Explain why diamond does not conduct electricity
Explain why diamond does not dissolve in water
Explain why diamond is one of the hardest known materials.
Why do you think Graphite is a softer material than both SiO2 and diamond?
How many bonds does each Carbon atom make in Diamond? ……. In Graphite?
Why does Graphite conduct electricity?
In terms of structure what does SiO2resemble………. How does this explain its properties?

39. Bonding in SiO2 ……………………
How many bonds does each silicon atom make ?
How many bonds does each Oxygen atom make?
What group is Silicon in? Use this information to explain why Si makes four bonds.
Why does Oxygen only make 2 bonds? Si

40. Silicon dioxide (SiO2) – explaining the observations……………..
Why does SiO2 have a high mpt?
Why Is SiO2 crystalline?
Why is SiO2 a non conductor of electricity?
Why is SiO2 a hard substance?
Why is SiO2 not soluble in water?

41. How can we extract Useful Metals From Minerals?

42. Examples of common and important metals. Iron Aluminium Gold Copper
Silver

43. What is an ore?
An ore is a volume of rock containing components or minerals in a mode of occurrence that renders it valuable for mining.
The impurities are removed so that the real metal can be seen or used.
Examples of metal ores are Haematite and Bauxite

44. Increasing reactivity
Extraction processes
The reactivity of a metal determines the method of extraction.
The Reactivity
Series
potassium
Increasing reactivity
sodium
Metals above carbon must be extracted using electrolysis.
calcium
magnesium
aluminium
(carbon)
zinc
Metals below carbon
can be extracted from the ore by reduction using carbon, coke, or charcoal.
iron
lead
copper
silver
Gold and silver often do not need to
be extracted. They occur native.
gold

45. Apply. The metal ores that can react with the carbon are: Copper Oxide
Iron Oxide
Zinc Oxide
This is because Carbon is more reactive than these metals therefore can REDUCE the metal oxide
Explain the terms OXIDATION and REDUCTION.

46. Oxidation and Reduction reactions – how do they work?
CuO + C
FeO + C

47. The Electrolysis of Molten Lead Bromide
Electrolysis is the decomposition of an ELECTROLYTE with an electric current.
N:\C5 EAM\IC5_9.swf ( use this file to explain the process of electrolysis)
Metals form at the Negative electrode
Non Metals form at the positive electrode
Reaction at the negative electrode:
Pb+2
Reaction at the positive electrode:
2Br-1 +
Lead Bromide
PbBr2
Heat

48. Electrolysis of Lead Bromide.

49. Reaction at the anode and cathode
The reactions are as follows:
at the anode:
2Br –(l) → Br2(g) + 2e– Oxidation
at the cathode:
Pb2+(l) + 2e– → Pb(l) Reduction

50. Extraction of Al from it’s ore by Electrolysis
( 7 minute video of the extraction )

51. Graphite (carbon) anodes
Electrolytic extraction
A bauxite / cryolite mixture is melted in a steel container containing a carbon lining.
Graphite (carbon) anodes
Tank
lined
with
carbon
cathode
Steel
case
Molten electrolyte
bauxite + cryolite
Graphite anodes are inserted into the molten electrolyte ready for electrolysis.

52. Oxygen formation Aluminium formation Anode (+ electrode)
2O2-(l)  O2 (g) + 4e-
Cathode (- electrode)
Al3+(l) + 3e-  Al(l)

53. Carbon dioxide formation at anode
Carbon dioxide is formed at the anode rapidly .
Explain why this is an added cost to the Al extraction industry.
Write a chemical equation for this reaction.
Why is there formation of carbon dioxide at the anode, explain in terms of ions, electrons and charge .

54. Extraction of aluminium using electrolysis – half reactions
Anode (+ve electrode)
2O2- (l)  O2 (g) + 4e-
Cathode (-ve electrode)
Al3+ (l) + 3e-  Al (l)
Overall
2Al2O3 (l)  4Al (l) + 3O2 (g)
The anode reacts to form carbon dioxide
C + O2  CO2

55. Why are metals so Important?
Uses related to strength, malleability, high melting point and electrical conductivity
Metals are bonded so that the positive nuclei are surrounded by a sea of electrons that are free to move – this explain conductivity.
Malleability the atoms have the ability to slip over the top of one another
High melting point – strong forces of attraction between the electrons and the +ve nuclei

56. How much metal can be extracted form it’s ore?

57. Quantitative Chemistry………
What does ram stand for?
Relative atomic mass
What does rfm stand for?
Relative formula mass.
Calculate the rfm of H2SO4. (H=1,S=32,O=16)
98g.
Calculate the rfm of Al2(SO4)3(Al=27,S=32,O=16)
342g

58. Calculating the % of an element in a compound.
Calculate the % of Nitrogen in NH4NO3.N=14; H=1;O=16)
35%
Calculate the % the metal in each of these compounds.
Copper chloride
Sodium Oxide
Iron (III) Oxide.

59. How much metal using %s
Calculate the mass of Copper that would be extracted from 75kg of the ore – Copper oxide.
Stage 1 – Calculate the % of copper in the compound.
Stage 2 – Using this % calculate the mass of Cu in 75kg.

60. Your turn………………….. The formula of red lead oxide is Pb3O4. Work out:
The rfm of the red lead oxide
The % of lead in red lead oxide
The mass of Pb that would be extracted from 150kg of the ore.

61. Question 2 Work out the % of copper in these minerals: Cuprite Cu2O
Chalcopyrite CuFeS2
Malachite Cu2CO3(OH)2
Calculate the mass of Cu that would be extracted from 3000kg of each mineral.

62. Using balanced Equations……..
Calculate the mass of MgO that forms when 10.5g of Mg is burned in excess air?
Write the equation for the reaction.
Identify chemicals in question.
Convert formulae to grammes using RFMs.
Calculate for 1g.
Calculate for quantity in question.

63. Questions……………………
What mass of copper oxide would form from the thermal decomposition of 1 tonne of copper carbonate?

64. Questions……………………
What mass of copper would form from the reaction of carbon with 0.75 tonnes of copper oxide?

65. I can calculate %s of element in a compound…..
Identify from the list those you can do and explain how they are done….
I can calculate rfms…….
I can calculate %s of element in a compound…..
I can calculate the mass of a metal that would be formed from a kg quantity of ore…………
I can balance and use chemical equations to calculate reacting masses using gramme quantities………
I can balance and use chemical equations to calculate reacting masses using gramme quantities using Kg quantities…..
I can balance and use chemical equations to calculate reacting masses using metric tonne quantities………