Here's why:
* Chemical Change: Involves the formation of new substances with different chemical properties. The atoms within the substances are rearranged, creating new bonds and breaking old ones. This leads to a change in the composition of the matter.
* Example: Burning wood - Wood (cellulose) reacts with oxygen to form ash, carbon dioxide, and water. The composition of the wood is completely changed.
* Physical Change: Involves a change in the form or appearance of a substance, but not its chemical composition. The molecules remain the same, even if their arrangement or state changes.
* Example: Melting ice - Ice (water in solid form) changes to liquid water, but the chemical composition (H₂O) remains the same.
In summary: While both chemical and physical changes can alter properties like color, shape, or state, only a chemical change fundamentally changes the composition of the matter.
