I'm not sure if I'm posting this in the right forum, so I apologize in advance if I'm not. I just have a question about the photoelectric effect. As I understand it, the photoelectric effect is where light/photons can knock electrons off a metal surface. I think that the intensity of the light gives the electrons more energy and the light frequency can knock more electrons loose. Anyway, my question is this: where do those electrons come from? I understand that most metal elements give up electrons easily, but if electrons are coming off the nucleus of, say, an atom of copper, doesn't this mean that the entire chemical structure of the copper is being changed?????? Could someone please resolve this question????