* Physical Changes: Involve alterations in the physical state of a substance (solid, liquid, gas) without changing its chemical composition.
* Evaporation is a prime example. Liquid water (H₂O) changes into water vapor (still H₂O) but the chemical formula remains the same.
* Chemical Changes: Involve the formation of new substances with different chemical compositions.
* Examples: Burning wood, rusting iron, cooking an egg.
In summary: Evaporation is simply a change in the state of water from liquid to gas, not a change in its chemical makeup.