Question

Explain the formation of bands and using band theory distinguish among conductors,
semiconductors and insulators.
​

Answer 1

Answer:

In a semiconductor, the valence band is completely filled with electrons while the conduction band is empty. ... If the temperature is 0K, there is no transfer of electrons from the valence band to the conduction band. Insulators: In insulators, the valence band is completely filled while the conduction band is empty.

Answer 2

Explanation:

Energy bands : In a solid , the energy of electrons lie within certain range. The energy levels of allowed energy are in the form of bands, these bands are separated by regions of forbidden energy called band gaps.

Distinguish features :

(a) In conductors : valence band and conduction band overlap each other.

In semiconductors : Valence band and conduction band are separated by a small energy gap.

In insulators : They are separated by a large energy gap.

(b) In conductors : Large number of free electrons are available in conduction band.

In semiconductor : A very small number of electrons are available for electrical conduction.

In insulators : Conduction band is almost empty i.e., no electron is available for conduction.