Question

The metallic lustre exhibited by sodium is explained by:
A. Diffusion of sodium ions
B. Oscillation of loose electron
C. Excitation of free protons
D. Existence of body-centred cubic lattice

Answer 1

Hint: Sodium is an element with symbol $\text{Na}$ and atomic number 11. Sodium is a metal. Metals have a bright physical appearance. Metals are shiny and lustrous. The colour of solid sodium is silvery-white. The free sodium metal does not occur in an environment prepared or obtained from its compounds.

Complete step by step answer:
Sodium is an alkali metal which is present in group 1 of the periodic table, as it has one valence electron. The atomic mass of sodium is 23. Sodium metal exists in various minerals such as rock salt, feldspar and sodalite. Sodium ions are soluble ions in aqueous solutions.
Let us discuss the physical properties of sodium metal along with their reasons:

S. No.	Physical properties	Reasons why sodium shows these properties
1.	Soft metal	Sodium is a soft metal. This is because of the large atomic size and valence electron. The metallic bonding between the atoms of sodium is not strong; thus it can be cut through a knife.
2.	Colour and lustre	The lustre of sodium metal is due oscillation of the loose electron of sodium metal. As, sodium metal has only one valence electron. This valence electron undergoes excitation and thus gives colour and lustre to the metal.
3.	Reducing agent	The sodium metal has only one valence electron. It would like to lose that electron and achieve inert gas configuration. That’s why sodium has high oxidation potential.

The metallic lustre exhibited by sodium is explained by oscillation of a loose electron, which is option ‘b’.

Additional Information: Applications of sodium metal:
(1) Sodium vapours produce brilliant yellow light, hence used in streetlights.
(2) In nuclear reactors, liquid sodium is used as a heat exchanger.
(3) The common sodium compound, sodium chloride is added to foods and used as table salt.

Note: Sodium belongs to group I or alkaline metals of the periodic table. The electronic configuration of Sodium is $\text{1}{{\text{s}}^{2}}\text{2}{{\text{s}}^{2}}\text{2}{{\text{p}}^{6}}\text{3}{{\text{s}}^{1}}$. Due to the presence of the same valence electrons, the chemical properties of the elements are the same. But, physical properties are not the same, the softness and oxidation of sodium is not the same as that of other elements present in its group.