Page 51 - NCERT Science Class 10 English Medium

Q U E S T I O N S

1. Why is sodium kept immersed in kerosene oil?
2. Write equations for the reactions of
(i) iron with steam ?
(ii) calcium and potassium with water
3. Samples of four metals A, B, C and D were taken and added to the
following solution one by one. The results obtained have been tabulated
as follows.

Metal Iron(II) sulphate Copper(II) sulphate Zinc sulphate Silver nitrate
A No reaction Displacement
B Displacement No reaction
C No reaction No reaction No reaction Displacement
D No reaction No reaction No reaction No reaction

Use the Table above to answer the following questions about metals
A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of Copper(II)
sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing
reactivity.
4. Which gas is produced when dilute hydrochloric acid is added to a
reactive metal? Write the chemical reaction when iron reacts with dilute
H SO .
2 4
5. What would you observe when zinc is added to a solution of iron(II)
sulphate? Write the chemical reaction that takes place.

3.3 HOW DO METHOW DO METALS AND NON-METALS AND NON-METALS REAALS REACT?
3.3 HOW DO METALS AND NON-METALS AND NON-METALS REAALS REACT?
DO
MET
3.3 HOW DO METALS AND NON-METALS REACT?CT?
CT?
3.3 HOW
3.3
In the above activities, you saw the reactions of metals with a number of
reagents. Why do metals react in this manner? Let us recall what we
learnt about the electronic configuration of elements in Class IX. We
learnt that noble gases, which have a completely filled valence shell, show
little chemical activity. We, therefore, explain the reactivity of elements
as a tendency to attain a completely filled valence shell.
Let us have a look at the electronic configuration of noble gases and
some metals and non-metals.
We can see from Table 3.3 that a sodium atom has one electron in its
outermost shell. If it loses the electron from its M shell then its L shell
now becomes the outermost shell and that has a stable octet. The nucleus
of this atom still has 11 protons but the number of electrons has
become 10, so there is a net positive charge giving us a sodium cation
Na . On the other hand chlorine has seven electrons in its outermost shell
+

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