What is the role of electrons in electrical conductivity?

The role of electrons in electrical conductivity is crucial and is primarily associated with their ability to move freely within conductive materials, such as metals. In conductors, atoms have electrons that are loosely bound to their nuclei, which allows these electrons to move easily throughout the material. This characteristic of free-moving electrons is what facilitates the flow of electrical current when a potential difference (voltage) is applied. When a voltage is applied across a conductor, the free electrons drift towards the positive terminal, creating an electric current.

In contrast, the other statements do not accurately describe the behavior of electrons in conductors. For instance, arguing that electrons repel each other to stop the flow of electricity ignores their ability to move together in a coordinated manner under an applied electric field. The suggestion that electrons become immobile in a conductor contradicts the fundamental principle of conductivity—if they were immobile, no current would flow. Lastly, stating that electrons do not participate in electrical current again misrepresents their essential role; without the movement of electrons, there would be no electrical current at all. Thus, the correct understanding of electrical conductivity hinges on the presence and mobility of free-moving electrons, which is accurately captured in the chosen answer.