Continuously, but always in a new unpredictable direction, i.e. Brownian motion. And I suppose if you keep measuring them fast enough, so much disturbance will

Continuously, but always in a new unpredictable direction, i.e. Brownian motion. And I suppose if you keep measuring them fast enough, so much disturbance will kick them off the atom, so they are no longer in the shell. The shell is what happens when the electrons are left alone. (Not completely sure about this part.)