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Uses of common metals. The importance of metals. Which metals are used most. Quantities of some common metals used. How to choose a metal. Common physical properties. 1.Metals conduct electricity. 2.Metals conduct heat. 4.Metals are malleable.
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Which metals are used most Quantities of some common metals used
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
Price of metals Two important factors are The abundance of the metal in the earth. The cost of extraction.
Cost per Tonne($) 10400 1300 42000 11200 71 million 3900
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
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)
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
(2)The table below gives the relative properties and prices of four metals 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 A-cheap,fair corrosion resistant (can be painted) (c) A bridge (d) A window frame D-malleable,fair corrosion resistant,not too expensive