TITLE: Electrons and ionization in an electric current
QUESTION [1 upvotes]: Conductors have free electrons to roam, but is that equivalent to continuous ionization of atoms in a conductor, say when an electric current is running through?

REPLY [1 votes]: It's tempting to think that in a metal the conduction electrons are pulled off their atoms and go rattling around leaving the ionised atoms behind. However this is at best a very misleading representation of what happens.
What happens in a metallic conductor is that the conduction electrons become delocalised. In effect they spread out and get fuzzy so they are spread out over all the atoms in the metal rather than being bound to a single atom. Any particular atom loses some of its own electron as that electron spreads out to cover other atoms, however it gains electron density from the other atoms as their electrons spread out so there is no net change.
The delocalised electrons occupy momentum states in a continuous band called the conduction band. When a current flows what happens is that the population of the momentum states changes slightly so there is a net momentum in the direction of the flow. The average electron density is not changed.
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