The difference between the densities of solids, liquids and gases is due to the distance between the particles in each state of matter.
The particles of a solid are very close together.
It melts when it changes from the solid state to the liquid state.
The particles remain close together, so there is usually only a small increase of volume.
The same mass of liquid will have slightly greater volume than the solid.
As density equals , the liquid will have slightly lower density.
The density of solid iron = 7.8 g/cm3
The density of liquid iron = 6.9 g/cm3
A substance evaporates when it changes from the liquid state to the gas state.
Its particles move freely and are very far apart, so there is a large increase of volume.
The same mass of gas will have very much greater volume than the liquid, and so will have much lower density.
The density of liquid oxygen = 1.1 g/cm3
The density of gaseous oxygen = 0.0014 g/cm3
|State||Distance between particles||Density||Density in g/cm3|
|Solid||Very close together||High||Solid iron = 7.8|
|Liquid||Slightly further apart than a solid||Slightly less than the solid||Liquid iron = 6.9|
|Gas||Very much further apart than a solid or liquid||Very much less than the solid or liquid||Oxygen gas = 0.0014|