Electrons have a theoretical rest mass. They can move at varying speeds through space, unlike photons. They ehxhibit quantum-characteristics in their behavior. If an electron collides with, say, an atom, does conservation of momentum apply in the classical sense or does measurable mass (an atom nucleus) evade this effect, and the energy exchange is effected only in the directly unmeasurable way, in this instance for example electron-electron momentum change (among other effects)? In case I ask it too vaguely, if you fire electron plasma towards an atom in a void, does the atom get blasted out of the jet's way, or is its movement in space left unperturbed? Turn this around, should the electron emitter experience recoil thrust from firing the plasma?