* Chemical Change: Involves the formation of new substances with different chemical properties. Bonds are broken and formed.

* Physical Change: Alters the form or appearance of a substance, but not its chemical composition.

In the case of water turning to steam:

* The chemical formula remains the same: H₂O (water) → H₂O (steam)

* The molecules are still made of two hydrogen atoms and one oxygen atom.

* The change is simply a change of state from liquid to gas due to increased energy.

Think of it this way: You can condense the steam back into water, showing that the chemical composition hasn't fundamentally changed.