Atom Vibration: Temperature & Conservation of Momentum

[algorithmDesi]

I know this question is probably fairly basic but I had a hard time finding an answer on google. Does a single atom vibrate/jiggle/oscillate if it has a temperature (ie is not at absolute zero)? Is this vibration random in direction? If it is random, wouldn't this violate the law of Conservation of Momentum?

 

[snorkack]

I know this question is probably fairly basic but I had a hard time finding an answer on google. Does a single atom vibrate/jiggle/oscillate if it has a temperature (ie is not at absolute zero)? Is this vibration random in direction? If it is random, wouldn't this violate the law of Conservation of Momentum?

No. A single atom does not vibrate (no restoring force) and it can be at absolute zero, which is equivalent to ground state (and systems bigger than one atom may also occupy ground state).

The single atom does, however, have uncertainty of its location and momentum and is therefore spread out as its wavefunction. Also a trait shared with bigger objects.

And of course the single atom is subject to internal vibrations - namely the orbital motion of electron/s inside the atom. And of nucleons.

 

[sophiecentaur]

A single atom is not at any 'temperature'. Temperature is only a concept for large numbers of atoms or molecules that interact and have a statistical distribution of kinetic energies (relative to the rest of them). An atom can vibrate when it is locked in a solid with 'restoring forces' due to those around it.