In quantum mechanics, the default for each subsequent element nuclear charge increases in the center unit, and the filling is spdf-electron configurations. We have a nuclear charge is on the surface, because the number of protons and number of neutrons in the nucleus such that on the surface of the kernel should be protons and neutrons, and neutrons inside only, that is, on the surface of the nucleus formed some shell. In addition, protons must build, as well as their e-coat attracts. The question can be considered in the calculation of the core point and for how long?
Our philosophy is that you can not describe the nature of the mathematical one hundred percent confirmed. But the aims, of course, to such a description is necessary.