protons and electrons

[meni ohana]

why the electrons don't collapase into the proton-center of the atom? is it centrifugal force?
thanks

[DaveC426913]

See the FAQ:
http://physicsforums.com/showpost.php?p=862093&postcount=2

[Bob S]

In the lowest bound state of an electron in hydrogen (proton), orbital angular momentum (centrifugal force) is not a concern. There is a very very small but non-zero probability that the wave function of the electron and the proton do overlap. But it is energetically impossible for the proton to absorb the electron, because the final state would be a neutron, which is about 1.3 MeV heavier than the proton.

But in beryllium-7 (4 protons plus 3 neutrons), a proton in the nucleus can absorb an orbital electron and the atom becomes lithium-7 (3 protons plus 4 neutrons), because it is energetically possible. This is a form of beta decay called electron capture. Its half life is about 53 days. See
http://www.britannica.com/nobelprize/article-48278