If you imagine a wire of copper(note that I am not talking about electricity at all). Just only a wire of copper or copper metal or whatever full of copper atoms.

We know that each copper atom has 1 electron in the most outer shell and is very loosely bound to the atom. but at that point of time, even though it is still loose, it is still bound.

At a room temperature, inside this wire, would these loosely bound electrons(1 for each atom) become free or not ? I checked and the binding energy for this electron is 7.72eV so at room temperature, I dont think any of these electrons become free. Do they or don’t ?


1 Answer 1


When we are talking about a conductor material (metal), we should consider the behavior in the bulk phase (ie. a lot of atoms together, generally in some kind of crystalline order). The electrons in this situation behave differently compared to a free atom - exactly because of the metallic bond between the atoms. The binding energy you cite is about how an electron behaves when you remove it from a single atom, hanging is space and leaving a positively charged ion behind.

In bulk metal when an electron leaves one atom it is not leaving a positive ion behind, other electrons come in. The leaving electron also spread around many other atoms, and not just hanging in vacuum. Imagine the situation as the electrons would be in a constantly moving crowd, where everyone is moving up and down and can step in to empty spaces. The situation is a little bit similar situation how delocalized electrons behave in organic molecules with two crucial differences:

  • the electrons are delocalized in the whole system, not just along one set of bonds,
  • energetically speaking there are more space than electrons, so electrons have some space to move.

If you look at electrons ie in benzene, some are delocalized in the aromatic ring, but they require significant energy to go to an excited state. If you look at the electrons inside the metal, the electrons with the most energy (around the Fermi level) can be excited with an infinity small energy, which can kick these electrons to different excited states and move them around.

  • $\begingroup$ If no current applied, why do valence electrons jump around ? They must have needed energy to absorb to become free electrons. $\endgroup$
    – Chemistry
    May 4, 2023 at 9:39
  • 2
    $\begingroup$ @chem They, aren't "free" just delocalised (and there's always thermal energy). $\endgroup$
    – Mithoron
    May 4, 2023 at 12:16

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