How do states of matter change properties?
Well, this is something that you could address yourself...
A given mass of a condensed phase, solid or liquid, has a SPECIFIC volume, i.e. the condensed phases have more or less constant density. On the other hand, a non-condensed phase, a gas, has NO specific density, and it will uniformly fill whatever volume of container in which it is confined....
And thus the (variable) densities of the gaseous phase dwarf the densities of the condensed phases. And this is something that has long been exploited by the steam engine.