electron movement

[Sequence]

We were talking about absolut in zero in chemistry last week and I thought of somthing, Absolut zero is the tempature at which molecules stop moving. What happens at the subatomic level? Do the electrons keep moving, or would they cease movement as well?

 

If they do keep moving, would a theoretical temp. even colder then 0 k cause them to stop orbiting the nucleus and fall to the center?

[Klaynos]

0K or temperatures below it are impossible to reach, so there is no situation ever reached where the electrons would stop their orbits. But at very low temperatures all the electrons are below the Fermi level.

[swansont]

nanoKelvin temperatures have been reached, and the atoms are still there, behaving like the theory predicts. It's the center-of-mass motion that would cease, though you wouldn't necessarily know it, as the Heisenberg Uncertainty principle tells you that you can't tell where the atoms are anymore.

 

Negative temperatures do exist as a non-steady state condition of a population inversion, and it's a useful measure, i.e. it's a meaningful description of the system. But normally it's a steady-state condition, and you are limited to T>0

[Sequence]

thanks guys, I have another question though.

 

Is there any force that is capable of fusing the electrons with the nucleus? I know this happens in neutron stars but is there any other force capable of doing it?

 

Probly a simple question but I havn't taken much in the way of physics.

[swansont]

You might think it's commonplace, since the particle have opposite charges and attract. But there's more to it. The reason it happens in neutron stars is gravity can overcome the degeneracy pressure; the electrons can't be in the same state as another electron from the Pauli exclusion principle.

 

The reaction does happen in other situations, though the cross-section is small, as it is mediated by the weak interaction and that is extremely short-ranged. You have to produce a neutrino as the result. You see this in electron capture reactions of some unstable nuclei that might otherwise beta-plus decay.

[Sequence]

alright, I think I got that.