Gallium arsenide, a material used to manufacture laser printers and compact disc players, has a band gap of 130 kJ/mol. Is GaAs a metallic conductor, a semiconductor, or an electrical insulator? With what group 4A element is GaAs isoelectronic? (Isoelectronic substances have the same number of electrons.)

Verified step by step guidance

1. Identify the type of material based on the band gap energy. A band gap of 130 kJ/mol is relatively small, indicating that GaAs is a semiconductor.
2. Recall that semiconductors have a band gap that allows them to conduct electricity under certain conditions, unlike metallic conductors which have no band gap, and insulators which have a large band gap.
3. Determine the number of valence electrons in GaAs. Gallium (Ga) is in group 3A and has 3 valence electrons, while arsenic (As) is in group 5A and has 5 valence electrons, totaling 8 valence electrons for GaAs.
4. Identify the group 4A element that is isoelectronic with GaAs. Group 4A elements have 4 valence electrons, and when combined in a compound like silicon (Si) or germanium (Ge), they also have 8 valence electrons, making them isoelectronic with GaAs.
5. Conclude that GaAs is isoelectronic with silicon (Si) or germanium (Ge), as these group 4A elements have the same number of total electrons in their compounds.

Key Concepts

Band Gap Energy

The band gap energy is the energy difference between the valence band and the conduction band in a material. It determines a material's electrical conductivity; materials with a small band gap (like semiconductors) can conduct electricity under certain conditions, while those with a large band gap (like insulators) do not conduct electricity well. Gallium arsenide (GaAs) has a band gap of 130 kJ/mol, indicating it is a semiconductor.

Semiconductors

Semiconductors are materials that have electrical conductivity between that of conductors and insulators. They can conduct electricity under specific conditions, such as when energy is supplied (e.g., heat or light). GaAs is classified as a semiconductor due to its band gap, which allows it to conduct electricity when energy is applied, making it useful in electronic devices like laser printers and CD players.

Isoelectronic Species

Isoelectronic species are atoms, ions, or molecules that have the same number of electrons, resulting in similar electronic configurations. In the case of GaAs, it is isoelectronic with silicon (Si), a group 4A element, meaning they both have the same number of electrons in their outer shells. This property is significant in understanding the behavior of materials in electronic applications.