The following diagram represents the electron population ofthe bands of MO energy levels for elemental silicon:
(a) Identify the valence band, conduction band, and band gap.

Verified step by step guidance

1. Observe the diagram and note the different colored regions. The red region represents the valence band, which is the highest range of electron energies where electrons are normally present at absolute zero temperature.
2. Identify the blue region above the red region. This blue region represents the conduction band, which is the range of electron energies higher than the valence band where electrons can move freely and conduct electricity.
3. Notice the gap between the red and blue regions. This gap is known as the band gap, which is the energy difference between the top of the valence band and the bottom of the conduction band.
4. Understand that the band gap is a crucial factor in determining the electrical conductivity of the material. For silicon, this band gap is relatively small, allowing it to act as a semiconductor.
5. Summarize the identification: The red region is the valence band, the blue region is the conduction band, and the space between them is the band gap.

Key Concepts

Valence Band

The valence band is the highest energy band that is fully occupied by electrons at absolute zero temperature. In semiconductors like silicon, it contains the electrons that are involved in bonding and determines the electrical properties of the material. When electrons in the valence band gain enough energy, they can move to the conduction band, allowing for electrical conduction.

Conduction Band

The conduction band is the range of energy levels that electrons can occupy when they are free to move within a material, contributing to electrical conductivity. In semiconductors, this band is typically empty at absolute zero but can be populated by electrons that have gained sufficient energy, such as from thermal excitation or photon absorption. The ability of electrons to move in this band is crucial for the conduction of electricity.

Band Gap

The band gap is the energy difference between the valence band and the conduction band in a semiconductor. It represents the minimum energy required for an electron to transition from the valence band to the conduction band. The size of the band gap determines the electrical and optical properties of the material, influencing its conductivity and the wavelengths of light it can absorb or emit.