What is the cause of temperature of an atom?How hot can Atoms get, in the Universe?

Answer 1

The answer depends on the heat source and the amount of heat the atom can absorb before the subatom particles start "moving too much" (e.g. vibration). At a certain temperature the atom becomes ionized (i.e., it looses one or more electrons), and it becomes an "ion". The temperature at which this occurs depends on the atom in question.

Answer 2

Temperature usually refers to the mean kinetic energy of a group of atoms. In this case, temperature can rise to hundreds of millions of Kelvins -- 300,000,000 K at the core of the sun and in solar flares.

At extreme temperatures, an atom is ionized -- its electrons are stripped away, leaving the charged core nucleus of protons and neutrons. So, in a way, there is a maximum limit to the temperature of an atom.

Answer 3

Atoms get hotter by rubbing against each other, that's why steam is steam, because the atoms are moving so fast, and rubbing against each other so hard they heat up, it turns into steam,

and as ice form, its frozen, and cold, because thereis absolutely no movement in the atoms.

So there is no standard temperature for an atom.

unless you mix certain substances with others, then you got yourself a chemical reaction, depends on the atomic structure of the compounds.