This document discusses the history of atomic theory from ancient Greek philosophers to modern atomic structure. It covers key discoveries such as the law of definite proportions, Dalton's atomic theory, the discovery of the electron, Rutherford's gold foil experiment, discovery of the neutron, and development of quantum numbers to describe electron configuration. Modern atomic structure is represented using electron shells, orbitals, and quantum numbers to explain periodic trends and chemical bonding.

1. The Atom Democritus Invisible Immortal Indivisible units

2. Aristotle Continuous matter

4. Joseph Proust (1754 – 1826) Law of Definite Proportions

5. Law of Definite Proportions Copper Carbonate: Regardless of the source, a compound always has the same proportion of elements

6. Law of Definite Proportions Copper Carbonate: CuCO 3 -> Copper + Carbon + Oxygen

7. Law of Definite Proportions Copper Carbonate: CuCO 3 -> Copper + Carbon + Oxygen 51.36% 9.72% 38.85%

8. Antoine Lavoisier Law of Conservation of Mass

9. Antoine Lavoisier Law of Conservation of Mass

10. Antoine Lavoisier Accounting for Oxygen gas

11. John Dalton Law of Multiple Proportions

12. Law of Multiple Proportions CO and CO 2 H 2 O and H 2 O 2 NH 3 and N 2 H 4

13. Law of Multiple Proportions NH 3 and N 2 H 4 N 2 + 3 H 2 ---> NH 3 N 2 + 2 H 2 ----> N 2 H 4

14. Law of Multiple Proportions NH 3 and N 2 H 4 N 2 + 3 H 2 ---> NH 3 28 g 6 g 34 g N 2 + 2 H 2 ----> N 2 H 4 28 g 4 g 32 g

15. Law of Multiple Proportions When elements combine to form more than one compound, different masses of one element compared to the mass of the other element are small whole number ratios.

16. Law of Multiple Proportions CO and CO 2 2 C + O 2 ---> 2 CO 24 g 32 g 56 g C + O 2 ----> CO 2 12 g 32 g 44 g

18. What is an Atom?

20. CRTs

21. Stream of Charged Particles

22. How much smaller? Robert Millikan found that the particles were 1/1840 the size of the Hydrogen atom

23. Plum Pudding Model Negatively charged particles embedded in a positively charged ball of matter.

24. The Discovery of Electrons J.J. Thomson found that the cathode ray particles were much smaller than the H atom

25. Rutherford’s Gold Foil experiment Ernest Rutherford directed alpha particles at gold foil

26. Planetary Model

27. The Discovery of the Neutron 1932 Finds particle with no charge that has a mass of 1 atomic mass unit

29. Atomic Numbers

31. Dalton’s Atoms

32. Atoms

33. Atomic Symbols Mass Number A = Sum of protons and neutrons Atomic number, Z = # of protons

34. Atomic Symbols Mass Number A = Sum of protons and neutrons Atomic number, Z = # of protons The number of neutrons for any atom will be the difference between A and Z (A – Z = # neutrons)

35. Writing Atomic Symbols Symbol Atomic mass protons neutrons 22 ???? ????? ????? 20 26 11 ???? 6 ???? ????? ??????

36. Writing Atomic Symbols Symbol Atomic mass protons neutrons 22 10 12 46 20 26 11 5 6 64 30 34

37. Isotopes Same atomic number Different Mass number Different # neutrons

38. Isotopes

39. Relative abundance Bromine: 35 protons Br-79 Br-81 50.697% 49.317%

40. Relative abundance Bromine: 35 protons (79)(0.50697) + (81)(0.49317) = 40 + 39.9 = 79.9 Br-79 Br-81 50.697% 49.317%

41. Listed Atomic Massed are Weighted Averages 35 Br 79.9

42. Same atomic mass??

43. What about Electrons? Why don’t electrons crash into the Nucleus?

44. Bohr Model of the Atom Niels Bohr 1913

45. Allowable Energy Transitions

46. Electromagnetic Spectrum

47. Properties of Waves As Wavelength increases, Frequency decreases. Wavelength x Frequency = λ x ν = velocity of Light = c

48. Emission Spectra

49. Atomic Emission Spectra

50. Schrödinger probability functions S orbital

51. P orbitals 3 types of p orbitals

52. D orbitals 5 types of d orbitals

53. How can electrons be ordered?

55. Energy Levels

56. Orbital Shapes S orbitals P orbitals

57. Orbital Shapes D orbitals F orbitals

59. Spin States