Solids:
* Natural: Wood, rock, ice, diamond, iron
* Man-made: Plastic, metal, glass, concrete, paper
Liquids:
* Natural: Water, oil, honey, blood, sap
* Man-made: Gasoline, alcohol, vinegar, paint, milk
Gases:
* Natural: Oxygen, nitrogen, carbon dioxide, helium, methane
* Man-made: Chlorine, propane, neon, argon, freon
Key differences:
* Solids: Have a fixed shape and volume. The particles are tightly packed and vibrate in place.
* Liquids: Have a fixed volume but take the shape of their container. The particles are close together but can move around.
* Gases: Have no fixed shape or volume. They expand to fill their container. The particles are far apart and move freely.
