S-Block Elements Test - 5

Cs has low ionisation energy and absorbs light of lower energy and emits radiations of higher energy.
Among the radiations in the visible spectrum, violet light has the highest frequency, and therefore each photon is associated with the highest amount of energy.

Metallic luster is due to oscillation of free electrons in the metallic lattice.

a) In dilute solutions of Na in ammonia, the solvated electrons have a deep blue colour, but in more concentrated solutions the solution takes on a bronze/copper colour.
b) The chemical equation is:
Na(s) + (x + y)NH₃(l) → Na⁺(NH₃)_x + e⁻(NH₃)_y
The solution conducts electricity because the solvated ions and electrons can carry the current.
c) The solution of sodium in liquid ammonia is quite stable in nature. But due to the addition of small amount of a catalyst such as FeCl_3, sodium reacts with ammonia to form sodium amide and hydrogen gas.

Both Na and NaH on reacting with water form sodium hydroxide and evolve hydrogen gas.

Lithium forms normal oxide Li₂O. It does not form per oxides or super oxides on account of its small size.

Superoxides by K and Rb
Peroxides by Na and Ba