The discussion centers on why electrons do not crash into atomic nuclei, highlighting the phenomenon of electron capture, particularly in isotopes like 26Al. It explains that electrons occupy discrete orbital shells around the nucleus, where they cannot emit the final quanta of energy needed to collapse into the nucleus. The conversation also touches on quantum mechanics, emphasizing that classical physics fails to accurately describe electron behavior, particularly in low energy states. The isomer effect and the role of kinetic energy in creating a repulsive force near the nucleus are also discussed, illustrating the complex interactions at play.
PREREQUISITESStudents of physics, nuclear physicists, and anyone interested in atomic structure and quantum mechanics will benefit from this discussion.
Jeff Rosenbury said:
I assume the issue is that since accelerated charges classically emit radiation and aside from some other rather rare events etc. must therefore continuously loose kinetic energy then they will eventually run into the nucleus at least classically. The answer is that in fact physics is not correctly described by classical physics but only by quantum physics which ideally under the approximation of being a closed system will take on only certain eigenfunctions with certain eigen energies or a superposition of such states. But there is a definite minimum energy state often called the ground state of which it can be in no lower state. There is a very straightforward explanation of this and is in most all elementary quantum texts such as in authors Rojansky, Schiff etc. on the treatment of the hydrogen atom. NOw when one considers relativistic effects and field interaction and 2nd quantization it does become more complicated - perhaps requires quantum field theory when one considers interaction with E&M field in its quantum description - for example the Lamb shift. Anyway in this case when one actually calculates up to infinite frequencies infinities arise and the theory in some sense breaks down. It typically requires ' renormalization ' to actually make sense(or nonsense) of the situation. This was and in some others opinion still is a breakdown and major problem with the theory and was especially troublesome for the pioneers such as Dirac and others - though now with the 'renormalization ' group which was actually from someone using it in phase transitions it is more readily accepted. The infinities in the perturbation when one gets to the higher and higher energies are not simply only from interaction with E&M field but involve also relativistic effects such as pair production and eventually higher energy particles etc. which are not clearly understood or as yet completely quantifialbe but anyway are such that they put a 'halt' on the otherwise infinities and give a finite answer which in fact turns out to be very close to ignoring all of the quantum field effects in the first place - actually the explanation is that using the given classical physical constants such as charge and mass are in fact taking this into account already and that in the infinite calculations which arose they should have been using quantities such as 'bare charge' and 'bare mass' which approach infinite limits such as to mostly cancel the infinite limits arising in the perturbation calculations. BUT anyway this is basically getting off subject.Multiple_Authors said:Multiple_Authors submitted a new PF Insights post
Why Don’t Electrons Crash into the Nucleus in Atoms?
Continue reading the Original PF Insights Post.
The comments above are all lacking a very essential aspect:Funley said:
Bernhard Kup said:
This sounds like an old-fashioned description. We still use the terminology of shells, but shells do not have a radius. The higher energy shells do have a higher average (expected value) radius, but the electrons have some probability of being at any radius.Jim Hasty said: