photoelectric effect - In photo-electric experiment, if the light is exposed to a metal plate for a long enough interval, does the plate become lighter?

I know from the book that electrons will be kicked out from the metal plate if the light of appropriate wavelength is exposed to the metal plate.

My mental model says if we let the light expose the plate in a long enough interval, the plate will have no electrons anymore. So what happens on the plate? Does it still looks like a plate as the original? Or it become lighter due to loss of electrons?

Answer

Well, it will become lighter with each electron removed, but unless you do it in the vacuum, it will get its electrons back from the environment.

Also, unless we are talking about really high energies, only the weakly bound valence electrons will be removed. The work to remove the electron, $W_a$, becomes higher the more electrons have left.

Okay, now if we suppose that you have somehow managed to remove all of the valence electrons, then sure, the plate will behave differently, as the optical and electrical properties are related to the electronic structure. If you have kicked out all (quasi-)free electrons, it might not be such a good conductor any more, for example.