What are energy bands

A large number of atoms in a crystal stone is closer to each other and more those electrons interact with themselves. The energy level of electrons in their shell is only caused because of the modification in their energy levels. The most important feature of Energy Bands is that the energy states for electrons are continuous in varied ranges. Thus, we can say that the energy level of an atom vary in valence bands and in conduction bands.

Since the electrons interact with other electrons, the energy associated with a material is altered so, the electrons are associated with a band of energy levels. The collection of energy levels which are partially or wholly filled are called valence band, and they are never empty. The collection of energy levels of the free electron which move freely around the material are called conduction band. There is an extra energy required to the conduction band by the valence electrons to move, which is termed as Forbidden energy.