What is the main factor that differentiates conductors from insulators?

The primary factor that differentiates conductors from insulators is the behavior of valence electrons. In conductors, such as metals, there are typically one or two valence electrons that are loosely bound to their atoms. This allows these electrons to move freely, which facilitates the flow of electrical current. Conductors have a high number of free electrons that enable them to conduct electricity efficiently.

In contrast, insulators, like rubber or glass, have a full valence shell of electrons, meaning their valence electrons are tightly bound to the atoms. This makes it difficult for electrons to move, thus preventing the flow of electricity. The inability of valence electrons in insulators to move freely contributes to their high resistance to electric current.

Understanding the role of valence electrons in electrical conductivity is fundamental in electrical engineering and related fields, as it underpins how materials are classified and used in various applications.