1. Metals
Chapter 35

2. What are Metals?
Metals are substances that tend to lose electrons to form positive ions.

3. Properties of Metals Metals are usually strong, hard and shiny.
They have high densities, high melting points and boiling points.
They are good conductors of heat and electricity.
They can be hammered into different shape(malleable)
They can be stretched out into thin wires(ductile).

4. To Test if a substance is a metal or a non-metal
One of the easiest ways of testing to see if a substance is a metal or a non-metal is to see if it conducts electricity.
Metals are good conductors of electricity. Therefore the bulb lights.
Non-metals do not conduct electricity.Therefore the bulb doesn’t light

5. Corrosion of Metals
Corrosion is any undesired process in which a metal is converted to one of its compounds.
When corrosion occurs the metal reacts with water, oxygen or other chemicals to form an oxide or some other compound.
The corrosion of Iron or Steel is called rusting.

6. Rusting The corrosion of Iron or steel is called rusting.
Rusting takes place in the presence of Water and Oxygen.

7. To investigate the conditions necessary for rusting.
Set up apparatus as shown.
Result
The nail in test tube 1 rusts.
The nail in test tube 2 doesn’t rust.
The nail in test tube 3 doesn’t rust
Conclusion
Water and Oxygen are
necessary for rust to take
place.

8. Prevention of Corrosion(rusting)
Most methods of rust prevention involve coating the metal
with some material to prevent oxygen and water coming in
contact with the metal.
The most important methods include:
Painting-bridges, ships, bicycles etc.
Greasing and oiling-car engines- bicycle chains, moving parts
Galvanising- coating the iron with a layer of zinc that does not rust Steel buckets, corrugated iron, wire for fencing.
Chromium Plating- taps, car bumpers etc.

9. Painting
Painting-bridges, ships, bicycles etc.

10. Greasing and oiling
Greasing and oiling-car engines- bicycle chains, moving parts

11. Galvanising
Galvanising- coating the iron with a layer of zinc that does not rust Steel buckets, corrugated iron, wire for fencing. .

12. Chromium Plating-
Chromium Plating- taps, car bumpers etc.

13. An alloy is a mixture of metals.
Metal Alloys
An alloy is a mixture of metals.
The alloys are usually much
harder and more resistant to
corrosion than either of the
metals they contain.
Examples of alloys include
Steel-Iron and Carbon
Bronze-Copper and Tin
Solder-Lead and Tin
Brass-Copper and Zinc

14. The Activity Series
Most reactive
Potassium(K)
Sodium (Na)
Calcium (Ca)
Magnesium (Mg)
Aluminium (Al)
Zinc (Zn)
Iron (Fe)
Lead (Pb)
Hydrogen (H)
Copper (Cu)
Mercury (Hg)
Silver (Ag)
Gold (Au)
The reactivity series is a list of metals in order of how reactive they are.
The most reactive metals are at the top .
The metals are arranged on the basis of how quickly they react in three tests (with Oxygen, Water and dilute HCl)
Least reactive

15. Reaction of metals with water
Set up apparatus as shown in
diagram.
Add water to each of the 4
metals.
Results:
Calcium-reacts vigorously with water
Magnesium-reacts vigorously with steam .
Zinc-reacts slowly with steam.
Copper-No reaction

16. Reaction of the Metals with Acids
Set up apparatus as shown in
diagram.
Add acid to each of the 4 metals.
Results:
Calcium-reacts very vigorously with
acid.
Magnesium-reacts vigorously with acid.
Zinc-less vigorous reaction with acid.
Copper-No reaction
Note: When metals react with an acid Hydrogen gas is given off

17. The reaction of Zinc with Hydrochloric Acid
Set up apparatus as shown in diagram.
The Zinc reacts with the Hydrochloric acid as follows:
Zinc + Hydrochloric Acid --> Zinc chloride + Hydrogen
Zn HCl ZnCl H2
Hydrogen gas is given off.
Test For Hydrogen
The Hydrogen gas, when ignited will burn with a popping sound. This is the test for Hydrogen