* Spacing of molecules: In liquid water, molecules are relatively close together, held by weak hydrogen bonds. In water vapor (gas), the molecules are much further apart. This increased spacing is a result of the molecules gaining enough energy to break free from the liquid's surface and move around independently.
* Volume: The same mass of water takes up a much larger volume in the gaseous state than in the liquid state.
* Density: Density is defined as mass per unit volume. Since the volume increases significantly and the mass stays the same, the density decreases dramatically.
Here are some approximate numbers:
* Liquid water: Density is about 1 gram per cubic centimeter (g/cm³).
* Water vapor: Density is about 0.005 g/cm³ at room temperature and atmospheric pressure.
This means that water vapor is about 200 times less dense than liquid water!
