- In a metal the valence electrons delocalize into the conduction band, becoming an "electron gas" that fills the metal's bulk volume.
- In covalent bonds the valence electrons are shared between local pairs of atoms.
- In ionic bonds the valence electrons leave the "metal" and move to the "nonmetal" creating a pair of separate oppositely charged ions.
- In resonance bonds the valence electrons oscillate between being shared between two nearby local pairs of atoms.
- etc.
To summarize in metals the valence electrons become delocalized, in other bonds the valence electrons stay local.
