Water Chapter 6:2

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

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 Polarity What does polarity mean?

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

Cohesion 7

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

Hydrogen Bonds 10

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

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

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