What happen to the distance between the particles when a liquid turn to gas?

Answer 1

Gas molecules take more room (volume) only (less than) 10% of the total, the rest space being empty!

Or...

Gas particles spread and the volume of them increases compared to the closer packed particles of a liquid. The number of particles stays the same but the force between then weakens because of the energy that they hold, these molecules spread.

This is because they have more kinetic energy than when they are a liquid, this is because evaporation ocours when heat energy is transferred to the molecules and then this results in the energy becoming kinetic* and causing the particles to escape from where they are into the air, spreading with there energy stores (energy that they hold).

* When the energy becomes kinetic, it basically causes the particles to vibrate as a transfer of the heat energy to them. Kinetic means movement and the (movement) energy makes the molecules bounce of one and other transferring the energy rapidly.

So this basically puts forward to why the particles manage to jump out of their container, as, if the energy is transerred to a particle in quite a big amount it will manage to escape. Thus once this happens on a larger scaleb(with more partcles), evaporation is happening!

_________________________________________________________________________________________________________It seems to me that the other answer above was a little brief... (and i'm not sure what the 10% thing means at all) Please edit this because i am not a rocket scientist and just tried to explain the theory as easily and clearly as possible.

Please note that if you read it all then you will understand the concept in more detail, rather than copying down the first sentence for your physics homework!