Dnk - I'm not sure I can see the image in your head, what you mean by oscilating? But as I understand it, electrons are really not sitting around at all. Electrons revolve about the necleus (center part) of an atom, and at a high velocity at that. You can think of it as if they "orbit" about the center nucleus. In most materials (kind of atoms), the nucleus has a firm hold on the electron which makes it very dificult and unlikely than an electron can escape and take off, either on it's own of under pressure (voltage). Some materials have a weak hold on their outermost orbiting electrons and it is fairly easy for one of them to escape.
Added to this is not only do electrons orbit the center nucleus of their atoms, they also spin or rotate. You have left spinning electrons and right spinning ones. This spin is what is said to be related to magnetism. You can see it gets complicated.
Back to your question, generally, electrons are trapped in their orbits. Sometimes, if an external outside force or pressure is applied, depending on a bunch of variables, it might be strong enough to overcome the hold of the atoms nucleus and the electron can escape and move with the direction of the pressure applied.
This is kind of a simplistic reply to a very complex issue.
Radar
