* Mass: Mass is the amount of matter in an object. It can change through:
* Adding or removing matter: If you add more material to something, its mass increases. Removing material decreases mass. This doesn't change the substance itself, just the quantity.
* Phase changes: Water, for example, has a different mass per unit volume as ice, liquid, or steam. This is due to changes in the arrangement of molecules, not the molecules themselves.
* Texture: Texture describes how a surface feels. It can change through:
* Physical processes: Crushing a rock changes its texture, but not its chemical composition.
* External factors: Weathering or erosion can smooth the surface of a rock, changing its texture.
Key takeaway: Changes in physical properties like mass and texture are physical changes. They alter the appearance or form of a substance but don't change the substance itself. The chemical composition (the types of atoms and how they are bonded) remains the same.
Examples:
* Cutting a piece of paper: Changes its shape and size (physical properties) but doesn't change the paper's chemical composition (it's still cellulose).
* Boiling water: Changes its state (physical change) but doesn't change the water molecules (it's still H₂O).
In contrast, chemical changes DO alter the substance's chemical composition. Burning wood creates ash, smoke, and gases, all of which have different chemical compositions than the original wood.
