And this guy states that our force due to this electron or on this electron due to this proton is given by k, a constant times the charge of our proton, times the charge of our electron divided by our distance r between them squared. And this is the force that this guy feels due to this guy and also the force that this proton feels due to this electron. Now, note that their forces are negative, but they have the same magnitude. So now let's look at helium. Remember, the outermost electrons are the electrons that will be pulled away. The inner electrons found on lower energy levels will not be pulled away first.