Well, as I begin moving them closer, they begin to feel electrostatic force Coulomb's law. Now, as I move them closer and closer, eventually I will bring them to a point when the electrostatic repulsion of the nuclei of the protons down the nuclei will balance out the electrostatic attraction between the electrons and the protons in the nuclei. In other words, let's look at the following example. So, when I have these two protons a certain distance apart, the repulsion between these two protons going this way will equal the attraction of these electrons. In other words, this proton of H atom one will attract the electron of H atom two. And likewise, H atom two will attract the electron of H atom one.