Physical changes involve alterations in the physical state or appearance of a substance without changing its chemical composition.
- Example: Melting ice into water is a physical change because the chemical composition remains the same.
Chemical changes involve the formation of new substances with different chemical properties.
- Example: Burning wood results in the formation of ash and smoke, indicating a chemical change has occurred.
| Feature | Physical Change | Chemical Change |
| Definition | Rearrangement of particles within a substance | Formation of new substances with different properties |
| Example | Melting ice, boiling water, crushing a rock | Burning wood, rusting iron, cooking food |
| Change in composition | No change | New substances are formed |
| Reversibility | Usually reversible | Usually irreversible |
| Energy change | Little or no change in energy | Energy is absorbed or released (heat, light) |
| Observable signs | Change in size, shape, color, state (solid, liquid, gas) | Change in color, formation of gas, production of heat or light, change in odor |