* No new substances are formed: When butter melts, it's still butter. The chemical composition (fat, water, milk solids) remains the same. It's just changing its state from solid to liquid.

* Change is reversible: You can easily solidify melted butter by putting it in the refrigerator.

Chemical changes involve the formation of new substances with different properties. For example, burning wood is a chemical change because it produces ash, smoke, and gases that are different from the original wood.