1. General Chemistry Element –composed of atoms Nucleus –protons (+) and neutrons (0) Electrons (-)

2. Figure 5.1

4. General Chemistry Molecule –a group of atoms held together by chemical bonds

5. General Chemistry Bonds –covalent bonds form when electrons are shared

7. General Chemistry Bonds –ionic bonds form by attraction between particles with opposite charges

9. Water H 2 O covalent bonds hold the 2 hydrogen & 1 oxygen together

10. Two hydrogen atoms... share their electrons with one oxygen atom... to form a water molecule held together by covalent bonds... which acts as if it has negative and positive ends. Nucleus ( + 1 unit of charge) Electron ( – 1 unit of charge) Stepped Art 2–2– 105 ° Fig. 6-1, p. 122

11. Figure 5.2

12. Water Water molecules have an uneven distribution of charge = polar or dipolar –H positive –O negative

13. Water Polar nature of water leads to: –attraction of other water molecules= cohesion –attraction of other charged or polar molecules=adhesion

14. Water Hydrogen Bonds –form between hydrogen of one water molecule and the oxygen of another

15. Figure 5.3

16. Fig. 6-5, p. 125 Hydrogen Bonds In An Ice Crystal

17. Fig. 6-4, p. 125

18. Figure 5.5

19. Water Universal solvent Solution –solvent –solute

20. Fig. 6-11, p. 129

21. Figure 5.4

22. Seawater 96.5% water & 3.5% solutes solutes change properties of water

23. Table 5.2

24. Figure 5.15

25. Salinity total concentration of all dissolved inorganic solids average = 3.5% or 35 ppt (35 o / oo )

26. Sources of Ocean’s salts weathering of surface rocks (stream run-off) –sodium, magnesium, calcium Outgassing (volcanoes and hydrothermal vents) –chlorine, carbon dioxide, sulfur, hydrogen

27. The Ocean is in Chemical Equilibrium Overall amount of dissolved salts in the ocean is nearly constant Additions of salts are balance by the removal of salts

28. Figure 5.19

29. Dissolved Gases Needed by organisms Gases dissolve more readily in cold water major gases –nitrogen48% –oxygen36% –carbon dioxide15%

30. Nitrogen Needed for proteins bacteria must “fix” the nitrogen most recycled among organisms

31. Oxygen More abundant in atmosphere (100x) than in ocean photosynthesis & diffusion add oxygen respiration by organisms uses up oxygen

32. Carbon Dioxide More abundant in ocean (about 60x) than in atmosphere respiration by organisms adds carbon dioxide Photosynthesis uses up carbon dioxide

33. Fig. 6-16, p. 133

34. Acid-Base Balance Use pH scale to measure acidity or alkalinity pH scales measure concentration of hydrogen ions (H+) pH scale is logarithmic…a change of 1 pH unit represents a ten-fold difference in H+ concentrations Low pH = acidic, high pH = basic

35. Figure 5.20

36. Fig. 6-17, p. 134

37. Acid-Base Balance Seawater pH is about 8, slightly alkaline CO 2 dissolves in water to form carbonic acid (H 2 CO 3 ) –Carbonic acid breaks down to H+, bicarbonate ion (HCO 3 - )and carbonate ion (CO 3 2- ) –this acts to buffer seawater from large swings in pH as acids and bases are introduced in the ocean

38. Figure 5.21

39. Acid-Base Balance Excess CO 2 can lower pH –This occurs in cold, deep water where respiration occurs but no photosynthesis –This low pH of 7.5 can dissolve calcium carbonate sediments Global change is causing ocean acidification

40. Fig. 6-16, p. 133