Question

Explain the chemical properties of alkali metals and explain inspite of highest ionisation enthalpy energy in the group, Lithium is a strong reducing agent why ?

Answer 1

Chemical Properties of Alkali Metals :
1. Reaction with Oxygen:- The alkali metals ternish in dry air due to the formation of their oxides. They form different of oxides like oxides peroxides and superoxides.

2. Reaction with Water:- The alkali metals react with water to form hydroxides and release dihydrogen.

3. Reaction with Dihydrogen:- The alkali metals react with dihydrogen at about 673 k (Li at 1073 K) to from hydrides.

4. Reaction with Halogens:- The alkali metals readily react vigorusly with halogens to form ionic halides,
e.g. 2M + X₂ ➝ 2MX
(Where M = Alkal metal like Na, K etc.)

5. Reaction with Liquid Ammonia:- The Alkali metals dissolve in liquid ammonia to give deep blue solutions.
M + (x + y)NH₃ ➝ [M(NH₃)_x]⁺ + [e[(NH₃)_y ]^–
Reducing nature of Lithium
Inspite of highest ionization enthalpy energy in the Group, lithium is a strong reducing agent because of the following reasons-

(i) Maximum hydration energy of lithium

(ii) Small size of lithium