# how does heat energy start to speed up a gas molecule?

If it was possible to place a single gas molecule in a cell and freeze it to near absolute zero. What would the molecule do as it thawed out?

Would it translate the heat energy into it's electrons and nucleus into vibrations and remain where it was? Would these vibrations cause it to start bouncing off the floor until it gets enough speed to convert the heat into kinetic energy?

Do gas molecules need convection to start speeding them up ( like the atmosphere), or do they translate heat into kinetic energy straight away all by themselves?

-

I don't think the definition of heat can be used down to the molecular level, as it is a macroscopic measure for the average vibrational energy of the different molecules. In the same way, you cannot define freezing for a single molecule as it describes a phase change, which you can only describe using a bunch of molecules.

Suppose you have a set-up that is capable of extracting all energy to "freeze" it, then there is also no vibration. Putting "heat" into the system is the same thing as adding vibrations to the molecule. So this comes from outside the molecule, not from the inside.

Convection is caused by the net displacement (flow) of molecules from one location to the other. Suppose you have a bunch of molecules, which are not of the same temperature, than diffusion will be the mechanism of heat transfer to surrounding molecules.

So it all comes down to: what is heat precisely, and that is a difficult to relate from macroscopic to molecular scales.

-
The question of molecular motion in response to "heat" is answered by statistical mechanics. If you have a single molecule at a temperature T, all that means is that the probability of any state of the molecule with energy E is as likely as $e^{-E\over T}$.