Do free electrons protons neutrons assemble into atoms?

a dull boy

Dear Physics Forum,

I wanted to know if there is any theory of elementary particles that explains why protons, neutrons, and electrons assemble into atoms? When these particles were first made in the Universe, why do the assemble into atoms? For example, why don't electrons simply bind protons in a 1:1 manner, and let the free neutrons decay? In a experimental preparation of electrons, neutrons, and protons, do they spontaneously assemble into atoms?

Atoms strike me as a somewhat arbitrary and overly complicated preparation of these components...Is there theory on this?

Thanks very much,
Mark

alemsalem

I think this might help:
http://en.wikipedia.org/wiki/Nucleosynthesis
specially big bang and stellar Nucleosynthesis

H2Bro

I believe protons and electrons will pair up quite easily if left alone together - after a few drinks, that is.

Nucleons (particles from the nucleus) won't without immense pressure, like inside of stars as alemsalem mentioned.

a dull boy

Thanks very much - the article on nucleosynthesis and the pressure dependence of nucleosynthesis were very helpful (after a few drinks!)
Best, Mark

sophiecentaur

Neutrons don't exist for very long on their own. Free neutrons have a half life of about 14 minutes. That implies they need to be in a relatively high concentration with protons etc before they are likely to combine into elements before they split back into protons and electrons.
You need 'stellar mass' for the process to work to any significant degree, I think.