1. Water Chapter 6:2

2. 2 Water Life is inextricably tied to water Covers almost ¾ of Earth’s surface Your body is made up of approximately 60% water

3. Polarity of Water water polarity animation 3 Water is polar (has charges). ***Remember- Electrons have a (-) charge, if Oxygen keeps electron longer than Hydrogen then Oxygen’s charge will be slightly (-).

4. 4 Polarity What does polarity mean?

5. 5 Polarity of water Within a water molecule, the bonds between oxygen and hydrogen are highly polar (charges unevenly distributed) Partial electrical charges develop –Oxygen keeps shared electrons longer so it is partially negative δ – –Hydrogen has shared electrons for less time so it is partially positive δ +

6. 6 Hydrogen bonds Cohesion –attraction between molecules of the same substance Attraction produces hydrogen bonds Each individual bond is weak Cumulative effects are enormous

7. Cohesion 7

8. 8

9. 9 Hydrogen bonds Adhesion –attraction between molecules of different substances Attraction allows water to bind to other substances

10. Hydrogen Bonds 10

11. Cohesion – water molecules stick to other water molecules by hydrogen bonding Adhesion – water molecules stick to other polar molecules by hydrogen bonding 11

12. 12 Properties of water 1.Water has a high specific heat specific heat : The amount of energy required to raise the temperature of 1 gram of a substance by 1  C. –A large amount of energy is required to change the temperature of water 2. Water has a high heat of vaporization –The evaporation of water from a surface causes cooling of that surface 3.Ice is less dense than liquid water –Bodies of water freeze from the top down 4.Water is a good solvent –Water dissolves polar molecules and ions 5. Water can form ions H 2 O  OH – + H + hydroxide ionhydrogen ion

13. 13 Properties of water 3.Ice is less dense than liquid water –Bodies of water freeze from the top down hydrogen ion

14. 14 Properties of water 4.Water is a good solvent –Water dissolves polar molecules and ions 5. Water can form ions H 2 O  OH – + H + hydroxide ionhydrogen ion