A covalent bond forms when atoms share electron pairs to create a chemical link, often between nonmetal atoms. This sharing allows atoms to achieve a stable electron configuration, similar to noble gases. Electrical conductivity refers to a material’s capacity to allow electric current to flow. This article explores whether substances primarily held together by covalent bonds are effective electrical conductors.
Understanding Electrical Conductivity
Electrical current flows when charged particles, such as electrons or ions, are free to move throughout a material’s structure. The ease with which these particles move determines conductivity.
Metals are excellent conductors because their valence electrons are not bound to individual atoms. Instead, they form a “sea” of delocalized electrons that can move freely when an electric field is applied. Ionic compounds conduct electricity when dissolved in a solution or in a molten state. In these conditions, their ions dissociate and become mobile.
Why Most Covalently Bonded Substances Don’t Conduct
Most substances formed through covalent bonds are poor electrical conductors because their electrons are localized. In a typical covalent bond, electrons are tightly shared between specific atoms and remain confined. This localization prevents them from moving freely throughout the material.
The electrons are held securely within discrete molecules or rigid network structures, like diamond. They are not available to carry an electrical current. Common examples of such insulators include water, sugar, plastics, and wood.
Covalent Materials That Can Conduct
While most covalently bonded materials do not conduct electricity, there are notable exceptions. Graphite, a form of carbon, exhibits electrical conductivity due to its unique layered structure. Within each layer, carbon atoms are covalently bonded in hexagonal rings, and some electrons are delocalized across these layers, creating a pathway for current to flow along the planes. Conductivity between layers is much lower because electrons are not freely shared in that direction.
Another class of conductive covalent materials are semiconductors, such as silicon and germanium. These elements are covalent but possess a unique electronic band structure that allows them to conduct electricity under specific conditions. At very low temperatures, they behave as insulators, but with increased temperature or the introduction of impurities through doping, electrons can gain enough energy to move and carry a current. This controlled conductivity makes semiconductors fundamental to modern electronics.