Can I explain the changes of state using particle theory?
Here's the good news. Yes, you can explain changes of state using particle theory.
Increased kinetic energy (add heat) causes the the bonds that hold particles in place to be broken and begin moving freely. This gives liquids the ability to flow.
Additional energy added to liquids causes even more increased kinetic energy. This can cause the particles to move at rapid speeds and spread out to fill whatever container they are inside of (or escape from a container which has an opening).
Here is a brief video which should be helpful.