04 The Chemistry of Life: Atoms and Molecules

1. 04 The Chemistry of Life: Atoms and Molecules

2. Elements Pure substances that cannot be broken down into simpler chemical entities by ordinary chemical reactions. Periodic Table 112 known elements

4. Major Elements Comprising the Biological Molecules of Living Things • Carbon • Hydrogen • Oxygen • Nitrogen • Phosphorus • Sulfur

6. Elements & Atoms An element is composed of atoms (0.1-1 nm in diameter) Atom cluster of small particles (proton, neutron, electron)

7. Subatomic Particles Protons (p +) Neutrons (n o) Electrons (e -)

8. Electron Shell Configurations of Atoms proton neutron electron hydrogen atom helium atom carbon atom 1p, 0n, 1e- 2p, 2n, 2e- 6p, 6n, 6e-

9. atomic number: number ofp; #p = #e- 2He2e- and 2p He

10. He atomic mass (atomic wt.): sum of masses ofp+n He 2p + 2n, atomic mass = 4 4 2He p + n e-

11. C Carbon Atom p = n = e- = Atomic number = Atomic mass =

12. C Isotope atoms that differ in the number of neutrons 12 6 C 13 6 C 14 6 C C12 C13 C14 stable stable isotope unstable- radioactive isotope

13. Molecule Two or more atoms held together by chemical bonds Oxygen O2 Nitrogen N2 Ammonia NH3 Carbon Dioxide CO2 Water H2O Methane CH4 Glucose C6H12O6

14. Compound Binding two or more different kinds of elements together NaCl + C6H12O6

15. Compound Binding two or more different kinds of elements together NaCl CH4 C6H12O6

16. Ion An atom that has either gained or lost electrons such that it exhibits a net charge Na+ Cl-

17. Sodium (Na) Atom 11 P+ 12 No

18. Sodium (Na+) Ion + 11 P+ 12 No

19. Chlorine (Cl) Atom 17 P+ 18 No

20. Chloride (Cl-) Ion _ 17 P+ 18 No

21. Some Examples of Ions Hydrogen H+ Potassium K+ Fluoride F- Calcium Ca+2 Magnesium Mg+2

22. Complex Ions Hydroxide OH- Bicarbonate HCO3- Nitrate NO3- Phosphate PO4-3 Ammonium NH4+ Acetate C2H3O2-

23. Bond Types: • Ionic • Covalent • Hydrogen

24. Ionic Bonds Transfer of electron 11 P+ 12 No 17 P+ 18 No

25. Covalent Bonding:electron sharing O H H

26. C Covalent Bonding:electron sharing H C H H H H H H H

27. Hydrogen Bonding Between Water Molecules Hydrogen bond Covalent bond

28. Hydrogen Bonding Between Different Molecules

29. Examples of Organic Molecules Lipids Carbohydrates Proteins Nucleic acids

30. Properties of Water • High heat capacity-absorbs and releases large amounts of heat (land heats faster than water) • High heat of vaporization- sweat, cooling mechanism • Polarity solvent properties- universal solvent • Reactivity- hydrolysis and condensation (dehydration)

31. Polarity of Water Molecules

32. Chemical Reactions A  B reactant  product

33. Chemical Synthesis A+BAB

34. Chemical Decomposition ABA+B

35. Chemical Rearrangement AB+CDAC+BD

36. Decomposition of Water H2OOH- +H+ O O + H H H H Hydroxyl ion [HO-] Water molecule [H2O] Hydrogen ion [H+]

37. pH • “p” stands for potential and “H” stands for hydrogen • Refers to the potential of a substance to attract hydrogen ions (H+)

38. Acids Proton donor, i.e., they donate H+ ions HCl is a strong acid with a pH 1-2 HCl  H+ + Cl-

39. Bases Proton acceptor, i.e., they take up H+ ions NaOH is a strong base ~pH 12 Na+ + OH- NaOH NH3 + H+ NH4 OH -+ H+ H2O HCO3 +H+ H2CO3

40. Neutralization HCl + NaOH H2O + NaCl

41. Buffer- resists dramatic changes in pH; ex. tums, rolaids…buffers stomach acid

42. pH Scale 0-14 Type of Solution pH Value Neutral 7 Acidic 0-6 Basic (alkaline) 8-14

43. pH Scale Logarithmic scale blood

44. Measuring pH

45. pH of Coke

46. Impact of Acid in our Body - CO2 + H2O H2CO3 HCO3+ H+ CO2 O2 O2 Bicarbonate Carbonic acid Capillary Cell

47. Impact of Acid in our Body HCl pH 1-2

48. Impact of Acid in our Body pH 8

49. Impact of Acid in the Ocean

50. Inquiry • How many neutrons in 7 N? • Of the following pH’s which is most acidic? • 3 7 6 2 • 3. The symbols K, Na, C, and S are: • 4. Which of the following are elements? • water; sugar; table salt; the atmosphere • 5. Which of the following are pure substances? • wine; seawater; blood; iron 14