1. The Wonderful World of Water

2. The importance of water
Water covers 71% of Earth’s surface

3. But not all of that water is usable

4. You are mostly made of water

5. In fact, water is crucial to life as we know it!

6. Life on Earth originated in the oceans

7. This is why astronomers look for planets in the “goldilocks zone” where liquid water could exist

8. It is thought that Mars once had liquid water
So life may have once existed there.

9. This simple molecule is involved in all aspects of our life.
It shapes land through erosion and weathering

10. It influences our climate (long term weather patterns)
Forms different types of air masses over land and sea, reflects sunlight using clouds and glaciers, forms precipitation, ocean currents and temperature influence local climates

11. Ancient civilizations settled near water and worshiped rain gods.
Wars have been fought over access to water

13. So what makes this simple molecule so amazing?
Water has some unique properties
A water molecule (H2O), is made up of three atoms --- one oxygen and two hydrogen. H

14. Water is Polar
In each water molecule, the oxygen atom attracts more than its "fair share" of electrons
The oxygen end has a negative charge
The hydrogen end has a positive charge
However, water is neutral (equal number of e- and p+) = Zero Net Charge

15. These charges allow water molecules to “stick” together
The negative oxygen end of one water molecule is attracted to the positive hydrogen end of another water molecule to form a HYDROGEN BOND

16. Animation: Water Structure
Right-click slide/select “Play”
© 2011 Pearson Education, Inc. 16

17. These hydrogen bonds allow for some interesting behavior by water
Phases of Matter
Heat Capacity
Cohesion
Adhesion

18. Phases of Matter Water exists in all three phases on Earth
At sea level, pure water boils at 100 °C and freezes at 0 °C.

19. Water vapor is made of water (H20) in gas form
Water vapor is made of water (H20) in gas form. The molecule is still made of three atoms.

20. Properties of Water
The boiling temperature of water decreases at higher elevations (lower atmospheric pressure).
For this reason, an egg will take longer to boil at higher altitudes (it takes longer to cook food at a lower temperature) 1

21. Water is Less Dense as a Solid
Ice is less dense as a solid than as a liquid (ice floats)
Liquid water has hydrogen bonds that are constantly being broken and reformed.
Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances. 1

22. Water is Less Dense as a Solid
Which is ice and which is water? 1

23. Water is Less Dense as a Solid
Ice 1

24. Cohesion
Cohesion: an attraction between molecules of the same kind.
Hydrogen bonds allow one water molecule to stick to other water molecules
This results in surface tension (a measure of the strength of water’s surface)
Surface tension 1

25. Surface tension created by cohesion…
Helps animals remain on the surface of the water

26. Adhesion Adhesion is the attraction between two different substances.
Water will form hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. 1

27. Cohesion vs. Adhesion
Cohesion- two alike substances attracted to one another
Adhesion- two different substances attracted to one another

28. Adhesion allows plants to pull in water
Capillary action - water molecules will “tow” each other along when in a thin glass tube or along a paper towel.
The thinner the tube, the higher the water can “climb”

29. Capillary Action in a paper towel
The water is adhering to the paper towel.

30. This calendar uses capillary action to absorb ink, one day at a time

31. Adhesion Causes Capillary Action
Transpiration is the water released from plant leaves

32. Transpiration: water vapor is released by plants.

33. Animation: Water Transport
Right-click slide/select “Play”
© 2011 Pearson Education, Inc. 33

34. Two types of water-conducting cells
Adhesion
Two types of
water-conducting
cells
Cohesion
Direction
of water
movement
Figure 3.3 Water transport in plants.
300 m 34

35. Water has high heat capacity
Water resists temperature change, both for heating and cooling.
Water can absorb or release large amounts of heat energy with little change in actual temperature.
Which takes longer to heat up? A pot with water or a pot with no water? 1

36. Heat Capacity of water influences the climate of areas near water

37. Los Angeles (Airport) 75°
Figure 3.5
San Bernardino
100°
Burbank
90°
Santa Barbara 73°
Riverside 96°
Los Angeles
(Airport) 75°
Santa Ana
84°
Palm Springs
106°
70s (°F)
80s
Pacific Ocean 68°
90s
Figure 3.5 Effect of a large body of water on climate.
100s
San Diego 72°
40 miles 37

38. Why does Phoenix AZ have a greater temperature range than San Diego CA?

39. Water, like all matter, cannot be created or destroyed
The same water molecules you drink today have been around for billions of years!
It originally arrived on earth from comets!
Measurements from the Herschel Space Observatory show that comet Hartley 2, which comes from the distant Kuiper Belt, contains water with the same chemical signature as water in Earth's oceans. The findings may help explain how Earth’s surface ended up covered in water.

40. Water is constantly recycled
The Water Cycle is the continuous process by which water moves from Earth’s surface to the atmosphere and back.
Driven by energy from the SUN.

41. 3 3 2

42. Processes of the Water Cycle
The Sun heats up the water in Earth’s oceans and lakes.

43. Processes of the Water Cycle
2. Evaporation: liquid water changes to a gas called water vapor.

44. Processes of the Water Cycle
Transpiration: water vapor is released by plants.

45. Processes of the Water Cycle
3. Condensation:
Warm air carries water vapor upward.
The air cools and condenses into liquid water.
Tiny droplets of water clump together around tiny dust particles in the air, forming clouds.

46. Licancabur Volcano is located on the border between Chile and Bolivia.

47. Processes of the Water Cycle
4. Precipitation:
As more water vapor condenses, the drops of water grow larger and heavier.
The heavy droplets fall as precipitation (rain, snow, sleet, hail).

48. Processes of the Water Cycle
5. The precipitation that falls on land may:
soak into the soil and become groundwater OR
Run off the land, eventually flowing back into the ocean.

50. Water that falls on the surface may run off into rivers and streams, eventually flowing back to a lake or ocean.

51. Water Cycle Video