Here's why:
* Physical changes alter the form or appearance of a substance, but not its chemical composition. Think about melting ice. It changes from a solid to a liquid, but it's still water (H₂O).
* Chemical changes result in the formation of new substances with different chemical compositions. Burning wood is a chemical change because it reacts with oxygen to form ash, carbon dioxide, and other products. The wood is no longer wood; it's a new substance.
Here's a simple way to remember:
* Physical changes are reversible: You can usually get the original substance back (like freezing water to get ice).
* Chemical changes are irreversible: You can't easily get the original substance back (like turning eggs into scrambled eggs).
Let me know if you'd like more examples!
