1. Properties of Water The most unusual usual liquid

2. MOLECULAR STRUCTURE Two atoms of hydrogen and one atom of oxygen H2OH2OH2OH2O

3. Water is a Polar Molecule A molecule that has a slight electric charge A molecule that has a slight electric charge – Hydrogen has a positive charge – Oxygen has a negative charge. The positive hydrogen ends attract the negative oxygen ends of another molecule. The positive hydrogen ends attract the negative oxygen ends of another molecule. Molecules stick together. Molecules stick together. + + - + + -

4. SURFACE TENSION Many of water’s unusual properties are because water is a polar molecule. Many of water’s unusual properties are because water is a polar molecule. Surface Tension: The tightness across the surface of water Surface Tension: The tightness across the surface of water – Causes a curved surface and round water drops – Created by water molecules pulling against each other.

5. CAPILLARY ACTION Capillary Action: The ability of water to pass through materials with pores. Capillary Action: The ability of water to pass through materials with pores. – Polarity of molecules cause water molecules to stick to the side of a material and pulls up other molecules. – Why towels oak up water.

6. THE UNIVERSAL SOLVENT Solvent: Any substance that dissolves another substance Solvent: Any substance that dissolves another substance Water is a good solvent because it is a polar molecule. Water is a good solvent because it is a polar molecule. – Attract other polar molecules and pulls them apart.

7. THE ONE AND ONLY Water is the only substance on earth that exists naturally as a liquid, solid, and a gas. Water is the only substance on earth that exists naturally as a liquid, solid, and a gas. Changing state = changing the amount of energy in a substance. Changing state = changing the amount of energy in a substance. – More energy = more movement = faster and more spread out. ICE (SOLID) WATER (LIQUID) VAPOR (GAS)

9. Why does ice float? When water freezes, the molecules attract in a matrix that takes up more space than the liquid form. When water freezes, the molecules attract in a matrix that takes up more space than the liquid form. This is very unusual. Most substances are more dense as a solid. This is very unusual. Most substances are more dense as a solid.

10. VOCABULARY Melting: When a solid changes into a liquid Freezing: When a liquid changes into a solid. Evaporation: When molecules at the surface of a liquid absorb enough energy from their surroundings to change into a gas. Condensation: When a gas turns into a liquid.