sentence: Electrons are forbidden from other energy levels.
sentences_before: In semiconductors and insulators, quantum mechanics show that electrons are only found in a number of bands of energy.
sentences_after: The term 'band gap' refers to the energy difference between the top of the valence band and the bottom of the conduction band. Electrons are able to jump from one band to another. However, an electron needs a certain amount of energy to jump from a valence band to a conduction band. The amount of energy needed differs with different materials.
concept_name: electron
headings: Band gap In semiconductor physics
categories: Quantum mechanics