2. 1 Chapter 3: Water and the Fitness of the Environment THINK, PAIR, SHARE:

3. 2 Chapter 3 Water and the Fitness of the Environment

4. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

5. Figure 3.1 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

6. 5 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

7. H O wants to fill this HH Covalent Bonding Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

8. 7 (a) (b) Name (molecular formula) Electron- shell diagram Structural formula Space- filling model Hydrogen (H 2 ). Two hydrogen atoms can form a single bond. Oxygen (O 2 ). Two oxygen atoms share two pairs of electrons to form a double bond. HH O O Figure 2.11 A, B AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

9. 8 Name (molecular formula) Electron- shell diagram Structural formula Space- filling model (c) Methane (CH 4 ). Four hydrogen atoms can satisfy the valence of one carbon atom, forming methane. Water (H 2 O). Two hydrogen atoms and one oxygen atom are joined by covalent bonds to produce a molecule of water. (d) H O H HH H H C Figure 2.11 C, D AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

10. H H Oxygen + + – – – – Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen. This results in a partial negative charge on the oxygen and a partial positive charge on the hydrogens. AIM: Why is water important to life? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

11. 10 AIM: Why is water important to life? Chapter 2 – The Chemical Context of Life Fluorine has the highest electronegativity. Why not neon or helium? Neon/Helium have a full valence shell and therefore are already stable all by themselves and will not attract electrons to be stable. In biology, we will focus on elements with high electronegativity like oxygen and nitrogen. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

12. Polar Covalent Bond AIM: How do atoms interact with each other? Chapter 3 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

13. Non-polar covalent bond AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

14. 13 AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

15. Hydrogen Bonds AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

16. ions Cation vs Anion The sodium and chloride ions are now attracted to each other and form an ionic bond. ionic bond = bond between two oppositely charged ions Ionic Bond AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

17. Salt crystals -Na + Cl - crystals are repeating arrays of Na + and Cl - held together by the electromagnetic force. -general name given to ANY ionic compound (not just sodium chloride (Na + Cl - ) held together in a lattice structure. Ex: Na + Cl - K + Cl - Mg 2+ Cl 2 - AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

18. Van der waals interactions Even non-polar molecules can have some positively and negatively charged region briefly and can very weakly bind to another. AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Figure 1. Two non-polar molecules (say H 2 ) come into close proximity Figure 2. By chance, the position of the electrons around one of the molecules (the one to the left) are more on one side of the molecule than the other causing one side to be slightly negative and the other side to be slightly positive. Figure 3. This will then induce a dipole in the neighboring molecule as the neighboring molecule’s electrons will be attracted to the slightly positive region of the first molecule resulting again in an ever so slightly negative side and an ever so slightly positive side. Of course, the negative and positive will form a very weak interaction.

19. 18 ◦ Reinforce the shapes of large molecules ◦ Help molecules adhere to each other Plasma membrane are stabilized by the additive affect of Van der Waals interactions between non-polar fatty acid tails of phospholipids. H bonds The two strands of a DNA molecule are held together tightly by the additive affect of many, many weak Hydrogen Bonds AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

20. Fig. 2-UN7 AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life

21. 20

22. Fig. 2-UN11 AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life

23. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

24. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

25. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

26. Water-conducting cells Adhesion Cohesion 150 µm Direction of water movement AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment How is water transported against gravity in plants?

27. Water-conducting cells Adhesion Cohesion 150 µm Direction of water movement AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment How is water transported against gravity in plants?

28. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

29. 28

30. A measure of how well a substance resists change in temperatures 1 kcal = 1,000 calories; amount of heat needed to raise the temp of 1kg of water AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Specific heat of iron: 0.1 cal/g/ o C

31. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Water, because of it H-bonding (cohesive nature) has a very high specific heat relative to other molecules. It is difficult to get the water molecules to vibrate since they are all sticking to each other. The H-bonds need to be broken. Think about this analogy: is easy to push a single student and get them moving fast, but if you all hold hands, it becomes more difficult as I would need to break those bonds. Helps organisms resist change in temperature!!

32. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

33. Water has a relatively high heat of vaporization because the hydrogen bonds of the water that must be overcome in order for evaporation to occur AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

34. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

35. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

36. Liquid water Hydrogen bonds constantly break and re-form Ice Hydrogen bonds are stable Hydrogen bond AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

37. Solvent: the dissolving agent in a solution Solute: the substance being dissolved Solution: a homogeneous mixture Aqueous solution: water is the solvent AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

38. “Cage” of water molecules surrounding each dissolved substance Hydration shell AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

39. This oxygen is attracted to a slight positive charge on the lysozyme molecule. This oxygen is attracted to a slight negative charge on the lysozyme molecule. (a) Lysozyme molecule in a nonaqueous environment (b) Lysozyme molecule (purple) in an aqueous environment such as tears or saliva (c) Ionic and polar regions on the protein’s Surface attract water molecules. ++ –– Figure 3.7 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

40. Rule of thumb: LIKE DISSOLVES LIKE AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

41. 40 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Rule of thumb: LIKE DISSOLVES LIKE

42. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

43. AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

44. 43 How would you make a 0.5-molar (0.5 M) solution of sodium chloride (NaCl)? 1.Find moles 2.Convert moles to grams (factor label method) 3.Add enough water to make 1 L Molarity = moles of solute liter of solution Moles = M * L 1. Moles = 0.5 M * 1 L = 0.5 moles 2.0.5 moles * _________g 1 mole Remember 1 mole = formula mass 58.5 = 29.3 g of NaCl and fill with water to 1 L

45. 44 ck72+nerd

46. 45 How many grams of acetic acid (C 2 H 4 O 2 ) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? 1.Find moles 2.Convert moles to grams (factor label method) Molarity = moles of solute liter of solution Moles = M * L 1. Moles = 0.1 M * 10 L = 1 mole 2.1 mole * _________g 1 mole Remember 1 mole = formula mass = 60 g of acetic acid 60

47. 46 What is the molarity of a solution made by dissolving 2.5 g of NaCl in enough water to make 125 ml of solution? 1.Convert grams to moles 2.Find molarity Molarity = moles of solute liter of solution 1.2.5 g * 1 mole g Remember 1 mole = formula mass 58.5 = 0.0427 moles 2. Molarity = 0.0427 moles 0.125 L Molarity = 0.34 M NaCl

48. 47

49. AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment H 2 O H + + OH - Hydrogen ion (aka… a proton) Hydroxide ion The oxygen atom is more electronegative than the hydrogens and pulls the shared electrons away from them, which can cause one of the hydrogens (a proton) to fall off.

50. H Hydronium ion (H 3 O + ) H Hydroxide ion (OH – ) H H H H H H + – + Figure on p. 53 of water dissociating H 2 O H + + OH - AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment It will transfer from one water to another to form H 3 O + This change can significantly change the pH of an aqueous solution

51. pH stands for potential hydrogen and measures the hydrogen ion concentration in an aqueous solution Logarithmic scale from 0 to 14 Difference of 10X in hydrogen ion concentration between any two pH values AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

52. Chapter 2 - The Chemical Basis of Life AIM: pH? Logarithms (logs) The log of a number is simply how many powers of 10 you can pull out of that number. Ex. log 1000 = 3 because you can pull three powers of 10 out of 1000 (10 x 10 x 10) or 10 3 = 1000 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

53. Chapter 2 - The Chemical Basis of Life AIM: pH? Logarithms (logs) Ex. Log 100,000 = 5 because you can pull out 5 powers of 10 from 100,000 or 10 5 = 100,000. AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

54. Chapter 2 - The Chemical Basis of Life AIM: pH? Logarithms log 10 2 = log 100 = log 10 3 = log 1000 = log 10 4 = log 10,000 = log 10 5 = log 10 6 = log 10 -1 = log.1 = log 10 -2 = log 10 -3 = log 10 -4 = 2 3 4 5 6 -2 -3 -4 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

55. Chapter 2 - The Chemical Basis of Life AIM: pH? Then if you take the negative log… The signs switch -log 10 2 = -log 10 3 = -log 10 4 = -log 10 5 = -log 10 6 = -log 10 -1 = -log 10 -2 = -log 10 -3 = -log 10 -4 = -2 -3 -4 -5 -6 1 2 3 4 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment pH = - log [H + ]

56. AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment What if the pH is 10 X higher?

57. pH = - log [H + ] [H + ] = 10 -6 M pH = - log [H + ] x = - log [10 -6 M] pH = 6 pH = - log [10 -7 M] pH = 7 [H + ] = 10 -7 M What if the pH is 10 X higher? 1. As [H + ] goes up, pH goes DOWN 3. A change in 1 pH corresponds to a 10 - fold change in [H + ] 2. As [H + ] goes down, pH goes UP

58. How many times more acidic is lemon juice than urine? 10,000X more acidic

59. How many times more basic is milk of magnesia (pH 11) compared to seawater (pH 8)? 1000X more basic

60. Increasingly Acidic [H + ] > [OH – ] Increasingly Basic [H + ] < [OH – ] Neutral [H + ] = [OH – ] Oven cleaner 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH Scale Battery acid Digestive (stomach) juice, lemon juice Vinegar, beer, wine, cola Tomato juice Black coffee Rainwater Urine Pure water Human blood Seawater Milk of magnesia Household ammonia Household bleach Figure 3.8 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

61. 1. What does the pH value tell us about the solution? 2. What happens to the pH as the [H + ] increases? 3. If the pH of a solution is increased by three pH units, how has the [H + ] changed? The H + (free proton) concentration [H + ] decreases 1000x lower [H + ]

62. AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

63. AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

64. 0101 2323 4545 6767 8989 10 11 12 13 14 More acidic Acid rain Normal rain More basic Figure 3.9 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment