1. Water

2. Properties of Water Polar molecule Polar molecule Cohesion and adhesion Cohesion and adhesion High specific heat High specific heat Density – greatest at 4 o C Density – greatest at 4 o C

3. Polarity of Water In a water molecule two hydrogen atoms form single polar covalent bonds with an oxygen atom. (Gives water more structure than other liquids) In a water molecule two hydrogen atoms form single polar covalent bonds with an oxygen atom. (Gives water more structure than other liquids) Oxygen has a partial negative charge.Oxygen has a partial negative charge. Hydrogen atoms have a partial positive charge.Hydrogen atoms have a partial positive charge. A water molecule is a polar molecule with opposite ends of the molecule with opposite charges. A water molecule is a polar molecule with opposite ends of the molecule with opposite charges.

4. Interaction Between Water Molecules Negative Oxygen end of one water molecule is attracted to the Positive Hydrogen end of another water molecule to form a HYDROGEN BOND

5. Hydrogen Bonds Exist Between Water Molecules Formed between a highly Electronegative atom of a polar molecule and a Hydrogen Formed between a highly Electronegative atom of a polar molecule and a Hydrogen One hydrogen bond is weak, but many hydrogen bonds are strong One hydrogen bond is weak, but many hydrogen bonds are strong Each water molecule can form hydrogen bonds with up to four neighbors. Each water molecule can form hydrogen bonds with up to four neighbors.

6. Bonds to 4 molecules directly

7. 20 Second Concept Check!

8. Hydrogen Bonds Hold water molecules together Hold water molecules together Extraordinary Properties that are a result of hydrogen bonds: Extraordinary Properties that are a result of hydrogen bonds: Cohesive behaviorCohesive behavior Resists changes in temperatureResists changes in temperature High heat of vaporization (specific heat)High heat of vaporization (specific heat) Expands when it freezesExpands when it freezes

9. Cohesion 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 water Produces a surface film on water that allows insects to walk on the surface of water

10. Surface tension, a measure of the force necessary to stretch or break the surface of a liquid, is related to cohesion. Surface tension, a measure of the force necessary to stretch or break the surface of a liquid, is related to cohesion. Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface.Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface. Some animals can stand, walk, or run on water without breaking the surface.Some animals can stand, walk, or run on water without breaking the surface. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 3.3

11. Cohesion = Surface Tension Helps insects walk across water

12. 20 Second Concept Check!

13. 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 -water molecules will “tow” each other along when in a thin glass tube. Capillary action -water molecules will “tow” each other along when in a thin glass tube.

14. Capillary action occurs when the forces binding a liquid together (cohesion and surface tension) and the forces attracting that bound liquid to another surface (adhesion) are greater than the force of gravity. droplets.

15. Adhesion Causes Capillary Action Which gives water the ability to “climb” structures

16. Plants rely on capillary action Cohesion among water molecules plays a key role in the transport of water against gravity in plants Cohesion among water molecules plays a key role in the transport of water against gravity in plants Adhesion, clinging of one substance to another, contributes too, as water adheres to the wall of the vessels. Adhesion, clinging of one substance to another, contributes too, as water adheres to the wall of the vessels.

17. Capillary Action = cohesion + adhesion

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

19. 30 Second Concept Check!

20. Homeostasis Ability to maintain a steady state despite changing conditions Ability to maintain a steady state despite changing conditions Water is important to this process because: Water is important to this process because: a. Makes a good insulator b. Resists temperature change c Coolant d. Ice protects against temperature extremes (insulates frozen lakes)

21. Specific Heat is the amount of heat that must be absorbed or lost for one gram of a substance to change its temperature by 1 o C. 3/4 of the earth is covered by water. The water serves as a large heat sink responsible for: Prevention of temperature fluctuations that are outside the range suitable for life. Coastal areas having a mild climate A stable marine environment

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

23. Evaporative Cooling The cooling of a surface occurs when the liquid evaporates The cooling of a surface occurs when the liquid evaporates This is responsible for: This is responsible for: Moderating earth’s climate (as mentioned before)Moderating earth’s climate (as mentioned before) Stabilizes temperature in aquatic ecosystemsStabilizes temperature in aquatic ecosystems Preventing organisms from overheatingPreventing organisms from overheating

24. Density of Water The density of water: 1.Prevents water from freezing from the bottom up. 2.Ice forms on the surface first —the freezing of the water releases heat to the water below creating insulation. 3.Makes transition between seasons less abrupt.

25. When water reaches 0 o C, water becomes locked into a crystalline lattice with each molecule bonded to the maximum of four partners.When water reaches 0 o C, water becomes locked into a crystalline lattice with each molecule bonded to the maximum of four partners. As ice starts to melt, some of the hydrogen bonds break and some water molecules can slip closer together than they can while in the ice state.As ice starts to melt, some of the hydrogen bonds break and some water molecules can slip closer together than they can while in the ice state. Ice is about 10% less dense than water at 4 o C.Ice is about 10% less dense than water at 4 o C. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 3.5

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

27. Water is Less Dense as a Solid WaterIce

28. 30 Second Concept Check!

29. Let’s recap… Your answer to each of the following will be either: 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Hold up either 1, 2, 3, 4 or 5 to show your response

30. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Water molecules creating a hydrogen bond with each other!

31. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Temperature of water rises and falls very slowly

32. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Hydrogen molecule is slightly positive

33. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Capillary action is brought on by this!

34. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Leads to surface tension of water

35. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Water freezes from the surface on down

36. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Oxygen molecule is slightly negative

37. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Plants rely on these TWO properties of water to transport water within

38. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density Bugs can walk on water due to this property!

39. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property allows our bodies to maintain homeostasis

40. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when trying to float the needle on water

41. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when dropping water onto a penny

42. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when using the tube to “draw” up water

43. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when freezing the water to see if it froze top/bottom first.

44. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when freezing the water to see if it froze top/bottom first.

45. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density These TWO properties were evident when transporting water on a string!

46. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when dropping substances onto pepper in water

47. 1. Polarity 2. Cohesion 3. Adhesion 4. Specific Heat 5. Density This property was evident when heating water versus oil.

48. How did you do?? Hold your cards up and rate yourself a 1-5… 1 = I didn’t learn anything … boo!  5 = I can repeat all of this information back to you already! Bam!