Why is that an atom doesn't absorb more than the required amount of energy.?

[srikanth]

consider a water molecule..
it is heated beyond its boiling temperature..it turns into wet and superheated steam..later
but what happens to..it..
??
please answer my question

 

[f95toli]

You can't heat a single molecule. The various phases of of water are COLLECTIVE phenomena and depends on the average kinetic energy of a LOT of molecules; the molecules themselves do not change as the water goes from e.g liquid to steam.

 

[srikanth]

but guess..wat is d amount of heat absorbed by a single molecule..?
if a molecule is subjected to some amount of heat hypothetically..den wat is d amount dat it can absorb...dat is wat I am tryin to know

 

[GRB 080319B]

Since the heat of vaporization of water is 40.65 kJ/ 1 mole of water, and there are 6.02 x 10^23 molecules in 1 mole of water, dividing 40.65/6.02x10^23 gives you 6.752 x 10^-20 J/ molecule to change state from liquid to gas. This is the amount of latent heat absorbed by a single water molecule. It's temperature doesn't change during the state change. After the water molecule absorbs that amount of energy, any additional energy will go into increasing the temperature of the water vapor, which as f95toli said, is the average kinetic energy of the system, or the mole of water in this case.