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The S-Block Elements

Question
CBSEENCH11007113
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Account for the following:
(i) Sodium imparts colour to the flame.
(ii) Sodium acts as a strong reducing agent.

Solution

(i) Due to low ionisation energy, when sodium metal or its salt is heated in a flame, the valence electron is excited to higher energy level. When this excited electron returns to the ground state, the absorbed energy is emitted in the visible region of the electromagnetic spectrum and hence the flame appears coloured. 
(ii) The reducing character of sodium is due to its low ionisation energy as a result of which it can easily lose its valence electrons and act as strong reducing agent. For example,
    Al subscript 2 straight O subscript 3 space plus 6 Na space rightwards arrow space 3 Na subscript 2 straight O space plus space 2 Al space space Cl subscript 2 space plus space 2 Na space rightwards arrow space space 2 NaCl

Some More Questions From The s-Block Elements Chapter

What is the nature of lithium compounds?

Group 1 elements are called alkali metals. Why?

Why caesium can be used in photoelectric cell while lithium can not be?

In aqueous solution, Li+ ion has lowest mobility. Why?

Lithium has highest ionisation energy in group 1 elements, yet it is strongest reducing agent. Comment.

The softness of group 1 elements increases down the group with increasing atomic number. Give reason. 

Which is the most reactive alkali metal and why?

Why alkali metals do not form M2+ ions?

Name the radio active element in group 1. How does it resemble with the remaining elements of the group?

Why alkali metals are normally kept in kerosene oil?

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