When will electrons fall into the nucleus?

[ajb]

So scientists still have no idea why those heavy particles form?

 

Cooper pairs in superconductors and superfluids are well understood. Wikipedia will direct you to references on this.

 

Cooper pairs in more exotic situations, like in quark matter maybe not so well.

[questionposter]

Cooper pairs in superconductors and superfluids are well understood. Wikipedia will direct you to references on this.

 

Cooper pairs in more exotic situations, like in quark matter maybe not so well.

 

What about those particles that are literally like electrons in every way except they are a little more massive? Why do those form? Why can't those ever form from decay or from gamma-ray interactions with matter?

Edited September 14, 2011 by questionposter

[ajb]

What about those particles that are literally like electrons in every way except they are a little more massive? Why do those form? Why can't those ever form from decay or from gamma-ray interactions with matter?

 

The muon and tau particles, and their antiparticles (also they have associated neutrinos).

 

It is not known why there are three generations of "electrons". This is quite a puzzle in the standard model.

 

I think they can be formed in decays and photon-matter interactions, just as the muon and tau are heavier than the electron they are disfavoured energetically. The discovery of these "heavy electrons" was via electron-positron scattering experiments.

[LawfulBlade]

Electrons spend some time in the nucleus, or (in classically thinking of them as having trajectories) pass through the nucleus from time to time. The cross section for interaction is small and nothing will happen that's not energetically favorable, so you will only see the electron capture occur under certain conditions.

 

The probability of finding an electron in the nucleus is zero; in probability maps of electron clouds, there are always nodes at the nucleus. They spend no time there.

[swansont]

The probability of finding an electron in the nucleus is zero; in probability maps of electron clouds, there are always nodes at the nucleus. They spend no time there.

 

There are nodes at r=0, but the nucleus is not a point.

[questionposter]

There are nodes at r=0, but the nucleus is not a point.

 

I thought an electron could pass harmlessly through the nucleus...

[swansont]

I thought an electron could pass harmlessly through the nucleus...

 

Yes. Nothing I've posted contradicts that.

[LawfulBlade]

There are nodes at r=0, but the nucleus is not a point.

 

Ah, you are correct. My mistake. Slightly sloppy wording in my classes, I suppose. We never had need to go farther with this topic than to say that there were nodes at the nucleus were electrons would never be found, and I never thought of it again.

[Dovada]

I guess there's some amount of energy confining an electron to an atom, so what would it take for an electron to actually fall into or get pushed into the nucleus? Or does it just never happen? Why does it only happen with particle accelerators? Can I make an atom so massive that the size of the nucleus meets the boundary of an electron? And if that happens, will nothing or something happen?

 

The subject relating to why in nature the electron and proton in atomic matter do not readily combine has created a lot of controversy, so much so, that this problem was the reason for the foundation of the quantum atomic model.

 

The Rutherford atomic model, which is still often taught today to introduce students to the more advanced aspects of quantum mechanics, and the Bohr quantum atomic model, is conceptually quite simple. Basically the atomic model is described as being self contained and consisting of a cloud of negative electrons which move in circular orbits around a stationary and more massive positively charged central nucleus.

 

The original Rutherford atomic model theory had inherent electrical problems, mainly because the prediction that an electron should release electromagnetic radiation while orbiting a nucleus, this would result in the negative electron eventually losing its energy and gradually spiraling inwards, and so would ultimately collapse into the positive nucleus.

To overcome this difficulty, Niels Bohr proposed, in 1913, what is now called the Bohr model of the atom. He suggested that electrons could only have certain classical motions.

 

The significance of the Bohr model is that the laws of classical mechanics apply to the motion of the electron about the nucleus, restricting motion of the electron by a strange quantum rule that is based on the assumption that the electron can only orbit the atom’s nucleus at distances governed at fixed energy levels which are defined by a single positive integer number (n) i.e. n=1 or n=2 or n=3 and so on etc.

 

Over the century this single positive integer number (n) i.e. n=1 or n=2 system became entrenched in the atomic model becoming an unshakable burden that irritated many physicist including Albert Einstein.

 

So you have definitely opened a bag of worms by asking this question.