We will observe and compare the hardness of various metals, including iron, copper, aluminium, magnesium, and sodium, in this activity.
Comparing
the Hardness of Different Metals
Aim
of the activity
To compare the hardness of different metals.
Materials
Required
1. Samples
of metals
2. Knife
3. Watch glass
4. Tongs
Procedure
1. Take samples
of metals and try to cut each with a knife.
2. Place a piece of sodium metal on a watch glass using tongs and cut with a knife
Observation
We observe that
1. Iron cannot be cut with a knife.
2. Copper and aluminium can be cut with more effort.
3. Magnesium is relatively soft and cut with some pressure.
4. Sodium is
very soft and it can be cut easily with a knife.
Explanation
Hardness
is the physical property of metals.
Metals
are quite hard, and their hardness varies from metal to metal. If we try to cut
even a thin rod of iron into two pieces, it will be very difficult. The same will be the case with metals like
copper, silver, etc.
But on the other hand, there are certain
exceptions like sodium and potassium, which are soft and can be cut with a
knife. The extent of hardness that a metal possesses depends upon the strength
of the metallic bond.
Conclusion
This
activity demonstrates the hardness of metals. We can conclude that –
1. Iron and
copper are very hard.
2. Aluminium
and magnesium are softer.
3. Sodium is
extremely soft.
This
property of metals depends on their position in the periodic table.
Caution: Always handle sodium metal with care. Dry it by pressing between the folds of a filter paper.
Frequently Asked Questions
1. Why is
sodium so easy to cut with a knife?
Answer
– Sodium is an alkali metal and is very soft.
2. Why is
sodium kept in kerosene?
Answer
– Sodium is highly reactive with water and moisture, so it is kept in kerosene.
Related Topics -
1. Activity 3.3
2. Activity 3.1
3. Solution of Chapter 3 Metals and Non-metals
5. Extra Questions of Chapter 3
6. Solutions of Class 10 Science all chapters
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