Properties That Stay the Same (Generally):
* Mass: The total mass of the substances involved remains constant, even though the substances might change form. This is a fundamental principle known as the law of conservation of mass.
* Atoms: The types and numbers of atoms present in the initial substances remain the same after a physical or chemical change. They are simply rearranged.
Properties That Change:
Physical Changes:
* Appearance: The way something looks (color, shape, texture) can change.
* State of matter: A substance can change between solid, liquid, and gas.
* Volume: The space a substance occupies can change.
* Density: The mass per unit volume of a substance can change.
Chemical Changes:
* Composition: New substances with different chemical properties are formed.
* Chemical Properties: The ability of a substance to undergo a particular chemical reaction changes. This includes properties like flammability, reactivity, and pH.
Examples:
* Physical Change: Ice melting into water. The water molecules remain the same, but their arrangement changes.
* Chemical Change: Burning wood. The wood combines with oxygen, forming ash, carbon dioxide, and other products. The original wood is no longer present.
Important Note:
While the law of conservation of mass generally holds true, there are some exceptions in nuclear reactions, where a small amount of mass can be converted into energy (as described by Einstein's famous equation, E=mc²).
