Thanks for the question dkv. What I mean is that the electron is not a point charge particle. Its charge is distributed within the critical radius of an actual time-independent wave (which can be calculated by using the Schroedinger equation) Similarly the energy of the wave is equal to the mass of the electron. This energy is also distributed within the critical radius. Thus the electron is this "blob" defined by this critical radius within which the mass and charge are both distributed. When interacting with this "blob" at a distance outside of the critical radius it acts like a point particle because the "blob" has a centre of charge and a centre of mass at the same point within it. In other words, an electron will experience another electron as a point charge; however, if the two electrons approach each other so that the distance between their centres of charge become less than the sum of their critical radii, they interact quantum mechanically; for example they could form a covalent bond. It then seems as if a short range force kicks in to bind the atoms together. It is thus not surprising that the critical radii are of the order of bond lengths.
Interestingly, when modelling the proton in the same way, its critical radius is of the order of the proton radius within the nucleus. Is this why we think that the nucleus is held together by a short range force. Maybe the nuclear forces are equivalent to covalent bonding on a smaller scale. This speculation will put the cat amongst the pigeons!!
