1. Chemical Foundations

2. Rattlebox moth Nature’s Chemical Language

3. Play many roles –Us –Other organisms –Physical environment Nature’s Chemical Language

4. Elements Fundamental forms of matter Can’t be broken down further 92 occur naturally on Earth 25 are essential for life

5. Most Common Elements in Living Organisms Oxygen Hydrogen Carbon Nitrogen

7. Trace Elements Additives to food Dietary deficiencies Essential to health

9. What is an Atom? Smallest particle that is still an element Subatomic particles: –Protons (+) –Electrons (-) –Neutrons (no charge)

10. HydrogenHelium electron proton neutron Examples of Atoms

11. Atomic Number # of protons All atoms of an element the same Atomic # H = 1 Atomic # C = 6

12. Mass Numbers Mass number (atomic mass) = Number of protons + number of neutrons Carbon: 6 protons + 6 neutrons = 12 Oxygen: 8 protons + 8 neutrons = 16

13. + + –– + – 2 2 2 Protons Neutrons Electrons Mass number = 4 + + 2e – Electron cloud Nucleus

14. Isotopes Different #s of neutrons

15. Radioisotopes Unstable nucleus Emits energy and particles Radioactive decay –fixed rate

16. Uses of Radioisotopes Radiometric/carbon dating –Ratio of C 14 to C 12 Tracers Radiation therapy Dangers

17. Uses of Radioisotopes

18. Will Atoms Interact? Depends on: # and arrangement of e-

19. Electron Shells Shells hold e- #s of shells –Close = lower energy filled 1st Hydrogen (H) Atomic number = 1 Electron Carbon (C) Atomic number = 6 Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8 Outermost electron shell (can hold 8 electrons) First electron shell (can hold 2 electrons)

20. Electron Vacancies Unfilled shells = likely rxn H, C, O, N –unfilled outer shells CARBON 6p+, 6e - NITROGEN 7p+, 7e - HYDROGEN 1p+, 1e -

21. Chemical Bonds, Molecules, & Compounds Bonds = electron interactions Form molecules Compounds e.g.. - H 2 O Molecules e.g. - O 2

22. Chemical Formulas Symbols Glucose is C 6 H 12 O 6 – 6 carbons – 12 hydrogens – 6 oxygens

23. Chemical Formulas Chemical equation shows rxn Reactants ---> Products Start and finish with = # of atoms HCL + NaOH  NaCl + H 2 O

24. Important Types of Bonds Ionic Bonds (salt, NaCl) Covalent Bonds (methane CH 3 ) Hydrogen Bonds (water)

25. Ionic Bonding Atom loses e- -> (+) cation Atom gains e- -> (-) anion Difference charge? Results?

26. Formation of NaCl Sodium atom (Na) –Outer shell e- ? Chlorine atom (Cl) –Outer shell e- ? Transfers e- Ions together as NaCl

27. Formation of NaCl Transfer of electron Na Sodium atom Cl Chlorine atom Na + Sodium ion Cl – Chloride ion Sodium chloride (NaCl) Na Cl Na + – – – Na + Cl –

28. Covalent Bonding Atoms share e- Single covalent bond Double covalent bond Triple covalent bond Molecular hydrogen

30. Polar or Nonpolar Bonds? Nonpolar: share electrons equally Polar: unequal sharing –Water –Will electrons spend more time with the nucleus of O or H?

31. Hydrogen Bonding Polar covalent molecules Attraction to oppositely charged atom Water molecule Ammonia molecule

32. Figure 2.10

33. Water No net charge Oxygen has a slight ______ charge Hydrogen has a slight ______ charge HH O

34. Properties of Water Temperature stabilizing –Absorbs more heat –Evaporation –Forms crystal-lattice structure –Wonders of ice!

35. Extra Photo 02.11x2

37. Properties of Water Cohesive –Due to hydrogen bonds –Increases surface tension –Vital property to many organisms Great solvent

38. Figure 2.12

39. Figure 2.16

40. Properties of Water Bonds to hydrophilic substances –Bonds to polar molecules Repels hydrophobic ones –Repels nonpolar molecules

41. Hydrogen Ions: H + Unbound protons Biological effects Form when water ionizes

42. The pH Scale Measures H + concentration of fluid Log scale (1 = 10X change) Highest H + Lowest H + 0--------------------- 7-------------------14 Acidic Neutral Basic

43. Examples of pH Pure water pH of 7.0 Acidic –Stomach acid: pH 1.0 - 3.0 –Lemon juice: pH 2.3 Basic –Seawater: pH 7.8 - 8.3 –Baking soda: pH 9.0

44. Acids & Bases Acids –Donate H + when dissolved in water –Acidic solutions have pH < 7 Bases –Accept H + when dissolved in water –Acidic solutions have pH > 7

45. Acid Deposition

46. Potential problem areas because of sensitive soils Potential problem areas because of air pollution: emissions leading to acid deposition Current problem areas (including lakes and rivers ) Areas Affected and Threatened by Acid Deposition

47. Extra Photo 02.18x2

48. Figure 2.18

49. Acid Rain

50. Extra Photo 02.18x1

51. Buffer Systems Minimize shifts in pH Partnership between weak acid and weak base

52. Blood pH Carbonic Acid-Bicarbonate Buffer System When blood pH rises, carbonic acid dissociates to form bicarbonate and H + H 2 C0 3 -----> HC0 3 - + H + When blood pH drops, bicarbonate binds H + to form carbonic acid HC0 3 - + H + -----> H 2 C0 3

53. Question of the Day My new laundry detergent proudly states “phosphate free”, why should I be interested if my detergent has phosphate? Should I continue to buy this detergent? Is it better? Safer?