I am wondering what would be the result if a piece of copper were to suddenly lose all its valence electrons, or in other words, if a piece of copper was to suddenly become a collection of copper cations.

Since the Coulomb force between all the positively-charged copper atoms/cations should immediately start to push the copper anions away from one another, this piece of copper should either immediately expand in physical size or perhaps begin to disintegrate, but what will actually occur I really don't know.

As far as what mechanism could suddenly force out all the valence electrons within a piece of copper, such as a copper strip for example, please reference the drawing below:

enter image description here

This drawing of mine is showing a conceptual electrical apparatus that would suddenly squeeze out the valence electrons within a copper strip using two very strong electrostatic forces generated by two negatively-charged parallel plates. (Offhand, how exactly this apparatus would be constructed mechanically I have no idea at this point. I'm mostly interested in finding out if the working principle of it is a sound one.)

It is showing 50 kV as a voltage number because I believe that should generate a pretty strong electrostatic force, but I really don't know this because I'm not an electrical engineer and my knowledge of electrostatics, electric fields, and Coulomb forces is very limited. Also, this drawing is showing this apparatus within a vacuum chamber to take away the dielectric effect that air would have if it is present between the spaces between the copper strip and the parallel plates.

The working principle of this apparatus is that once the HV DC power supply is turned on, the valence electrons within the copper strip will be suddenly compressed towards its center and they should quickly exit out of the copper strip through an attached ground wire that would be soldered to the center of it.

This sudden expulsion of valence electrons should then instantly turn the copper strip into a collection of copper cations and the Coulomb force acting between all these cations should result in some sort of sudden physical change to the copper strip.

This is not a homework question. I am asking it simply out of my own scientific curiosity and to improve my overall understanding of electrostatics.

What would happen to a piece of copper if it were to suddenly lose all its valence electrons?


All the electrodes would need to be thickly coated with an electrical insulating material that would stop any electrical current between the electrodes yet would also have a low dielectric constant to allow electrostatic force to pass through it.

It would also have to be a material that could withstand very high electrical voltages so it doesn't have a quick dielectric breakdown. I believe the only material that could be used is diamond. If all the electrodes could be coated with a thick layer of poly diamond film, then I think this experiment with copper would work.

  • $\begingroup$ The word "explode" leaps to mind. :-) $\endgroup$ Sep 16, 2020 at 2:04
  • $\begingroup$ There's a mistake in your drawing. You labelled the "power supply" box "100kV," but the plates that are attached to it are labelled "0V" and "50kV." If the power supply created a potential difference of 100kV, then there should be two objects in your drawing somewhere that have 100kV potential difference between them. $\endgroup$ Sep 16, 2020 at 12:28
  • $\begingroup$ Also note, You used the "⏚" symbol in your drawing, but then you also labelled other parts of your drawing with "0V." But those labels both mean the same thing. "⏚" (a.k.a., "ground") in an electronic schematic diagram means "0V." (P.S., you actually don't need the red "0V" plates at all. Just connecting the copper bar to the power supply as shown will be enough to deplete it of electrons. The thing that you have built effectively is a vacuum capacitor, and the copper bar is (part of) it's positive plate. $\endgroup$ Sep 16, 2020 at 12:37
  • $\begingroup$ P.P.S., 50kV or 100kV is nowhere near enough to make any interesting thing happen. You can get voltages like that just by walking across a wool carpet on a dry winter day. See Andrew Steane's answer (below) for some "interesting" numbers. $\endgroup$ Sep 16, 2020 at 12:39
  • $\begingroup$ @SolomonSlow, thanks for pointing out those flaws out in my drawing and with my overall design. The only thing I can say is that I'm not an electrical engineer so I would have to consult with one in order to properly build something like this. Also, I'm not sure how high the voltage would need to be to force the valence electrons out of the copper strip. $\endgroup$
    – user255577
    Sep 16, 2020 at 13:27

1 Answer 1


Here is a quick back-of-the-envelope response. I recommend you try your own estimates to get further information.

Say we have one tenth of a mole of copper, and just remove one electron per atom. Then the remaining copper carries a positive charge of $$ Q = 0.1 \, N_A e \simeq 9700 \; {\rm coulomb} $$ That's a huge charge. It will present huge forces. For example, if it is spread over 100 square centimetres then the electric field nearby will be of order $$ \frac{\sigma}{\epsilon_0} = \frac{Q}{A \epsilon_0} \simeq 10^{17} \; {\rm volts\; per\; meter} $$ Don't go near such an object! This field will rip you apart.

And this is also the field you will have to supply in order to remove all those electrons.

Now consider one of the copper ions. The field at a distance of one atomic radius away from a charge of $1e$ is $$ \frac{e}{4\pi\epsilon_0 r^2} \simeq 10^{11} \; {\rm volts\; per\; meter} $$ This means that if you can supply the field mentioned above, then you will also find that this field is easily enough to pull apart the atomic-level structure of the copper block. The coppers ions will fly apart and rapidly hit the walls of your lab. There they will pick up electrons, if they have not already done so in their journey through the air.

But you will not be able to generate these fields using ordinary materials. The electrodes will start making sparks long before you get to these levels. You could do it using intense laser pulses. What tends to happen in practice in that case is that the laser pulse creates a plasma at the surface of the copper.

Of course you might like to modify your concept to something more achievable. Then the numbers will change. Certainly it is possible to remove charge from a lump of metal by using a strong electric field. It is just that extracting all the valence electrons is rather ambitious (to make an understatement).

  • $\begingroup$ I am thinking that by enclosing all the electrodes (parallel plates) in glass should stop them from making sparks because glass is an excellent insulator yet still allows an electrostatic charge to pass through it. I was thinking of showing the electrodes enclosed within glass in my drawing, but I didn't want to make the drawing too complex to easily understand. $\endgroup$
    – user255577
    Sep 16, 2020 at 0:19
  • $\begingroup$ also, I would upvote your answer but I am unable to upvote due to having a low reputation score. $\endgroup$
    – user255577
    Sep 16, 2020 at 2:30
  • $\begingroup$ @user255577 Glass will suffer dielectric breakdown well before you get to those electric field strengths (dielectric strength of only about $4\times10^7$ V/m). At those levels it's unlikely you will find any material will not have already broken down by then. $\endgroup$
    – Triatticus
    Sep 16, 2020 at 7:44
  • $\begingroup$ @Triatticus, I think perhaps only a diamond would not suffer dielectric breakdown. It is an electrical insulator and has a very low dielectric constant. If all the the electrodes could be coated with a thick poly diamond film, then it might be possible for them to withstand very high electric field strengths. $\endgroup$
    – user255577
    Sep 16, 2020 at 11:20
  • $\begingroup$ See this article for a description of a “coulomb explosion”. $\endgroup$ Sep 19, 2020 at 8:16

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