Water changes to water vapor at its boiling point or by evaporation.
Turning a vapour into a liquid is called condensation.
When water changes to water vapor, it has changed its state from liquid to vapor and no chemical change has taken place. It's only a physical change.
evaporation
This is a physical change. Liquid water and water vapor are the same thing. Water the liquid, when it is boiling, the water evaporates and becomes water vapor. Water vapor is much lighter than air...