A physical change is a change in the form or appearance of a substance without a change in its chemical composition. During a physical change, the atoms in the substance remain the same and are simply rearranged or redistributed. For example, when water freezes, the water molecules rearrange themselves into a crystalline structure, but the individual water molecules themselves remain unchanged.
In contrast, a chemical change is a change in the chemical composition of a substance, resulting in the formation of one or more new substances. During a chemical change, the atoms in the original substance are rearranged and bonded together in different ways, forming new molecules with different chemical properties. For example, when water is electrolyzed, the water molecules are split into hydrogen and oxygen gases, which are two new substances with different chemical properties than water.
