Evaporation is a physical change it is not a chemical change.
It is a physical change because it is going from the liquid phase to the gas phase. It is not a chemical change because it is still made of two hydrogen atoms and an oxygen atom.
Evaporation does not result in any chemical reaction, nor any breaking or making of chemical bonds. If you consider water before evaporation, it is #H_2O(l)# , if you then consider water after evaporation it is #H_2O(g)# . It is still #H_2O# - the molecule hasn't changed, all that has changed is the physical state.
A chemical change is one in which changes to chemical structure occur during the change, i.e. a chemical reaction occurs so that chemically different substances are present after the change, compared to before the change.
