1. I The Properties of Water

2. 3A water molecule (H 2 O), is made up of 3 atoms --- one oxygen and two hydrogen. H H O

3. 1. Water is Polar oxygen atom attracts more electronsIn each water molecule, the oxygen atom attracts more than its "fair share" of electrons oxygennegativeThe oxygen end “acts” negative hydrogenpositiveThe hydrogen end “acts” positive POLARCauses the water molecule to be POLAR neutral Zero Net ChargeHowever, Water is neutral (equal number of e- and p+) --- Zero Net Charge

5. Negative Oxygen end of one water molecule is attracted to the Positive Hydrogen end of another water molecule to form a HYDROGEN BOND 2. Cohesion

6. Attraction between particles of the same substance (why water is attracted to itself)Attraction between particles of the same substance ( why water is attracted to itself) Results in Surface tension (a measure of the strength of water’s surface)Results in Surface tension (a measure of the strength of water’s surface) Produces a surface film on water that allows insects to walk on the surface of waterProduces a surface film on water that allows insects to walk on the surface of water

7. H Bonds attract other Water Molecules Formed between a highly Electronegative atom of a polar molecule and a HydrogenFormed between a highly Electronegative atom of a polar molecule and a Hydrogen One hydrogen bond is weak, but many hydrogen bonds are strongOne hydrogen bond is weak, but many hydrogen bonds are strong

8. Cohesion cont… Helps insects walk across water

9. 3. At sea level, pure water boils at 100 °C and freezes at 0 °C. It takes a longer time for water to boil at higher elevations (lower atmospheric pressure).It takes a longer time for water to boil at higher elevations (lower atmospheric pressure). For this reason, an egg will take longer to boil at higher altitudesFor this reason, an egg will take longer to boil at higher altitudes

10. 4. Adhesion Attraction between two different substances.Attraction between two different substances. Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. Capillary action occurs when water molecules will “tow” each other along when in a thin glass tube.Capillary action occurs when water molecules will “tow” each other along when in a thin glass tube. Example: transpiration is the process which plants and trees use to remove water. As water evaporates form the leaves then more water is pulled in from the roots.Example: transpiration is the process which plants and trees use to remove water. As water evaporates form the leaves then more water is pulled in from the roots.

11. Adhesion Also Causes Water to … Form spheres & hold onto plant leaves Attach to a silken spider web

12. 5. High Specific Heat This is the mount of heat needed to raise or lower 1g of a substance 1° C.This is the mount of heat needed to raise or lower 1g of a substance 1° C. Water resists temperature change very well, both for heating and cooling.Water resists temperature change very well, both for heating and cooling. Water can also absorb or release large amounts of heat energy with little change in actual temperature.Water can also absorb or release large amounts of heat energy with little change in actual temperature.

13. 6. High Heat of Vaporization Vaporization is the amount of energy needed to convert 1g or a substance from a liquid to a gasVaporization is the amount of energy needed to convert 1g or a substance from a liquid to a gas In order for water to evaporate, hydrogen bonds must be broken and this takes a lot of heat energy.In order for water to evaporate, hydrogen bonds must be broken and this takes a lot of heat energy. As water evaporates, it removes a lot of heat with it, used in sweating to cool you bodyAs water evaporates, it removes a lot of heat with it, used in sweating to cool you body

14. High Heat of Vaporization cont… 540 cal/g.Water's heat of vaporization is 540 cal/g. In order for water to evaporate, each gram of the water must GAIN 540 calories (temperature doesn’t change --- 100 o C).In order for water to evaporate, each gram of the water must GAIN 540 calories (temperature doesn’t change --- 100 o C). As water evaporates, it removes a lot of heat with it (cooling effect).As water evaporates, it removes a lot of heat with it (cooling effect).

15. Water vaporWater vapor forms a kind of global ‘‘blanket” which helps to keep the Earth warm. Heat radiated from the sunHeat radiated from the sun warmed surface of the earth is absorbed and held by the vapor by the vapor.

16. 7. Water is Less Dense as a Solid Ice is less denseIce is less dense as a solid than as a liquid (ice floats) hydrogen bonds constantly being broken and reformed.Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water crystal-like latticeFrozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

17. Homeostasis Water is important in maintaining homeostasis in organisms because it:Water is important in maintaining homeostasis in organisms because it: a. Makes a good insulator b. Resists temperature change c. Is the Universal solvent d. Is used as a Coolant e. Is used when an Ice to protect against temperature extremes (insulates frozen lakes)

18. II Acids, Bases and pH Water molecules dissociate into a Hydrogen Ion (H+) and a Hydroxide Ion (OH-) causing acids and bases. Hydrogen Ion Hydroxide Ion Acid Base Acid Base H 2 O  H + + OH -

19. 1. The pH Scale concentration of H + ions in a solutionIndicates the concentration of H + ions in a solution 0 – 14It ranges from 0 – 14 7 is neutral (pure water)pH of 7 is neutral (pure water) 0 up to 7 is an acidpH 0 up to 7 is an acid … hi in H + ions above 7 – 14 is bpH above 7 – 14 is basic…hi in OH - ions 10XEach pH unit represents a factor of 10X change in concentration Ex. pH 5 is stronger than a pH of 6Ex. pH 5 is stronger than a pH of 6

20. 2. Acids Acids produce lots of H + ions in solutionAcids produce lots of H + ions in solution

21. 3. Bases Bases 8 to 14 and lots of OH - ionsBases have a pH of 8 to 14 and Contain lots of OH - ions and fewer H+ ions in solution.

22. 4. Buffers Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH is called neutralization= H ions + OH ions=water, ex. Antacids.Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH is called neutralization= H ions + OH ions=water, ex. Antacids. Buffers are also Produced naturally by the body to maintain homeostasis.Buffers are also Produced naturally by the body to maintain homeostasis.