Question

What is the forbidden energy gap or band gap?

• A. conduction band
• B. when there is no energy
• C. the forbidden energy gap is the difference between energy levels of the conduction band and within the conduction band.
• D. the forbidden energy gap is the difference in energy levels of the conduction band and valence band

Answer 1

The correct option is D

the forbidden energy gap is the difference in energy levels of the conduction band and valence band

Energy bands

1. The organization of molecules in gas compounds is more dispersed and not as close together. The particles in liquids are nearer together. However, because molecules in solids are densely packed together, atoms of molecules prefer to travel into the orbitals of neighboring atoms. As a result, whenever atoms come alongside, their electron orbitals overlap.
2. Because of the intermixing of atoms in solid, various bands of energy levels are generated. These groups of energy levels are referred to as energy bands.

Classification of energy bands

Valence band:

Valence electrons constitute electrons throughout the outermost shell. Such valence electrons have a sequence of energy levels and comprise the valence band.

Conduction band:

Since the valence electrons are not strongly bound to the nucleus, a few of them exit the topmost orbit by becoming free electrons even at an ambient temperature called as the conduction band.

Forbidden energy gap:

1. The forbidden gap would be the space between the valence band and the conduction band. The forbidden gap, as the name implies, has no energy and therefore no electrons remain in this band.
2. If somehow the forbidden energy gap is larger, the electron in the valence band has been strongly bound or firmly connected to the nucleus. We need a number of external sources of energy equivalent to the prohibited energy gap.

Therefore, option D is the correct choice.