* Physical Changes: Alter the form or appearance of a substance but not its chemical composition.

* Chemical Changes: Result in the formation of new substances with different chemical properties.

Boiling water only changes its state of matter from liquid to gas (steam). The water molecules themselves remain the same (H₂O).

Here's what happens:

* Heat energy is added to the water molecules, causing them to move faster and further apart.

* When the water reaches its boiling point (100°C or 212°F), the molecules have enough energy to break free from the liquid state and become a gas.

No new substances are formed, and the water can be easily returned to its liquid state by cooling the steam.