1. Uses of common metals

2. The importance of metals

3. Which metals are used most
Quantities of some common metals used
Metal
Tonnes per year Fe Al Cu Au
2 000

4. How to choose a metal

5. Common physical properties
1.Metals conduct electricity
2.Metals conduct heat.
4.Metals are malleable.
3.Metals are shiny (though a few metals turn dull after exposure to air)
5Metals are ductile.
Differences in physical Properties
1. Hardness and strength
2. Density
3. Melting point

6. Resistance to corrosion

7. Price of metals Two important factors are
The abundance of the metal in the earth.
The cost of extraction.

8. Reasons for choice of metal
Uses
Reasons for choice of metal Al
Cooking foil,drink cans
Window frames
Overhead electricity
Low density,strong,very Fe
Ship building and bridge
Strong,cheap Sn
Tin plate,as found in food cans
Non-toxic,resists corrosion Cu
Wires
Water pipes
Ductile,good conductor of electricity,strong,malleable,resists corrosion Au
Jewellery,decoration
protective
Shiny and attractive,the most malleable metal
Good reflector of heat and light Pb
batteries
Soft,dense and heavy,resists corrosion Ti
Supersonic aircraft
Light,but very strong
Corrosion resistant
Cost per
Tonne($)
10400
1300
42000
11200
71 million
3900

9. CLASS PRACTISE (1)
In the past, copper was used to make these cables.Give at least
Two reasons for the choice of copper.
(b) Aluminium is used today.Give some reasons for the change.
Sodium is an excellent conductor of electricity and is light
(density =0.97g/cm³).Why is it not used to make overhead
electricity cables?
(d) The cables have a steel wire in the centre.Give a reason.
good electrical conductor ,ductile.resistant to corrosion,not too expensive
Aluminum.Cheaper,much lighter (therefore pylons can be made more
Cheaply to support the lighter weight).It is also a good electrical conductor
And resistant to corrosion
Too soft,not very ductile,reacts with air and water
To provide more strength to the cable.
The figure shows overhead
electricity cables

10. What property of chromium is used?
Why are the handlebars not solid chromium?
Shiny appearance
Expensive
The handlebars of a bicycle are made of iron covered with a thin layer of chromium(Cr)

11. Imagine gold is cheap and iron is expensive . List:
(a) Some advantages of making a car from gold and not iron
Shiny,attractive, malleable, resistant to corrosion
(b) Some disadvantages.
Too heavy

12. (2)The table below gives the relative properties and prices of four metals
Malleability and ductility
Density
Heat conductivity
Electrical conductivity
Corrosion resistance
Price A
Fair
Medium
fair
Cheap B
Good
Low
Very good C
High
Expensive D
medium
good
Decide which of the four metals,A to D,you would choose to make the following,
objects.Give reasons for your choice.
A saucepan
B-light,corrosion resistant,not too expensive
B-ductile,light,good electrical conductor,corrosion resistant,not too expensive
(b) Electrical wires
(c) A bridge
A-cheap,fair corrosion resistant (can be painted)
(d) A window frame
D-malleable,fair corrosion resistant,not too expensive

13. THANK YOU