Question

Metallic lustre is explained by:
(A) Oscillation of loose electrons
(B) Diffusion of metal ions
(C) Excitation of free protons
(D) Existence of BCC lattice

Answer 1

Hint: Luster refers to the way the light is reflected from the surface of the material. If the material is metal, the lustre produced is known as metallic lustre. It is related to the interaction of light with the material surface.

Complete step by step solution:
Let’s know what lustre is first.
Lustre is characterized by the interaction of light with the surface of the material. It relates to the gloss or shine of the material.
-Metallic lustre is the gloss that such metallic material has as a natural property. Let’s see the science behind such property.
-Actually, the metals are lustrous because of the presence of the free electrons in their structure.
-We know that metals are placed in either s-block or in d-block in the periodic table. So, their valence electrons are either in s-orbital or in d-orbital.
-So, as the incident light imparts on the metal surface, the electrons there absorb the energy of photons and get excited and start oscillating due to the energy of the photons. Then, the oscillating protons lose energy and come back to the ground state. In this process, they emit a certain wavelength. So, the light is emitted in all the directions.
e.g. Sodium
So, we can conclude that metallic lustre can be explained by the oscillation of loose electrons.

Therefore the correct answer to this question is (A) Oscillation of loose electrons.

Note: Remember that lustre is of two types, metallic lustre and nonmetallic lustre. Metals like Gold, Platinum and sodium possess this property. Non-metals like iodine also possess lustre property.