* Physical Changes: Alter the form or appearance of a substance, but not its chemical composition. These changes are often reversible.

* Chemical Changes: Result in the formation of new substances with different chemical properties. These changes are often irreversible.

When you bend copper, you're changing its shape, but you're not altering the chemical makeup of the copper atoms. The copper remains copper, just in a different form. You could potentially straighten the copper back out, reversing the change.

Example: If you were to burn copper, that would be a chemical change. The copper would react with oxygen to form copper oxide, a completely different substance.