Why Do Substances Undergo Radical Changes During Phase Transitions?

[loom91]

Hi,

I was wondering, what actually are phase transitions such as fusion or evaporation? I know thermodynamic definitions such as points where the Gibbs energy is non-analytic or heat capacity changes abruptly, but these say nothing about mechanism. Why does a substance suddenly change its characteristics radically? Thanks.

Molu

 

[oghenez]

http://en.wikipedia.org/wiki/Phase_transition