What are free electrons?

Free electrons are best described as electrons that have been lost by an atom. In various contexts, including electrical conductivity and chemical bonding, free electrons refer to those electrons that are no longer associated with a specific atom and are instead able to move freely throughout a material. This concept is essential in understanding how certain materials can conduct electricity, especially in metals, where these free electrons facilitate the flow of electrical current.

The other options outline different concepts regarding the nature of electrons in atoms. Electrons that are tightly bound within an atom or found in the outermost orbit of an atom are not classified as free electrons because they are still associated with a specific atom. Additionally, electrons that are shared between atoms pertain to covalent bonding, which also does not align with the definition of free electrons. Therefore, the correct understanding of free electrons revolves around those that have been detached from their parent atom, enabling their movement and interaction within various environments.