1. Chapter 3 Atomic Theory

2. Today’s Objectives Understand the basics of Dalton’s Atomic Theory, and how it relates to the study of chemistry; be aware of how it differs from the currently accepted modern Atomic Theory. Know the basic details of how each subatomic particle was discovered, and what information was determined about protons, neutrons, and electrons in these experiments

3. Early Theories 4 elements

4. Democritus (460 - 370 BC) Greek philosopher Atomos – indivisible particles Atoms are the smallest particle that retains the chemical identity

5. Jabir Ibn Haiyan (700? - 803 AD) Father of Chemistry Practiced Alchemy Discovered metals

6. Lavoisier (1743 - 1794) Law of Conservation of Matter

7. Joseph Louis Proust (1754-1826) Law of Constant Composition

8. Dalton (1766 - 1844) Atomic Theory

10. Elements made of atoms Atoms are identical of a given type of element Atoms neither created nor destroyed Compounds have fixed ratio of atoms

11. Ben Franklin (1706-1790) Two types of charge positive (+) and negative (-)

12. Michael Faraday (1791-1867) Atoms are related to electricity

13. J.J. Thomson (1856 - 1940) Cathode Ray Tube (CRT) stream of electrons Plum Pudding Model

14. cathode ray tube

16. Robert Millikan (1838-1953) Determined charge & mass of electron

18. Becquerel (1852 - 1908) Uranium exposes film

19. Marie (1867-1934) & Pierre Curie (1859-1906) Discovered radioactivity elements Radioactive decay

20. Rutherford (1871 - 1937) Discovered radioactivity particles Discovered Nucleus Solar system model of atom

21. Discovery of particles

22. gold foil experiment

23. Niels Bohr (1885 – 1962) Electrons do not orbit like planets Described shells or energy levels Quantum theory

24. H.G.J. Moseley (1887 - 1915) Discovered protons (+) in the nucleus Rearranged periodic table

25. Sir James Chadwick (1891-1974) Discovered neutrons (0) in the nucleus

26. Today’s Objectives Review History of the atom –Dalton’s Theory –History and discovery of each subatomic particle Discovery Learning: –Know the name, location, charge, and relative mass of each of the subatomic particles in an atom –Know that the atomic number is the number of protons in the nucleus of an atom, and is unique to each element. –Understand that isotopes are atoms of the same element that differ in the number of neutrons in the nucleus, and therefore differ in mass. –Know the mass number is, and be able to use it to correctly designate isotopes using both hyphen notation and nuclear symbols.

28. Protons Make up the nucleus Charge +1.602 x 10 -19 C Mass = 1.673 x 10 -24 g Charge +1 Mass = 1 amu

29. Neutrons Make up the nucleus Charge 0 Mass = 1.675 x 10 -24 g Mass = 1 amu

31. Quarks, Quarks, Quarks (1950s – present) 6 quarks have been discovered that make up protons and neutrons

32. Electrons Occur in electron Clouds Charge -1.602 x 10 -19 C Mass = 9.109 x 10 -28 g Charge = -1 Mass = 0 amu

33. Atoms are small but nuclei are smaller Diameter of a penny has 810 million copper atoms

34. Atomic Number Number of protons in an atom Electrically neutral atoms have the same number of electrons as protons Ions are formed by gaining or losing electrons

35. Atomic Mass The mass of the nucleus, number of protons and neutrons. It is an average of all the isotopes masses

36. Isotopes Same number of Protons but different numbers of neutrons Mass number is the sum of the protons and the neutrons Isotopes have the same chemical properties Violates Dalton’s atomic theory

38. Masses of Atoms 1 amu = 1/12 mass of a 12 C atom 99% Carbon 12 C 1% Carbon 13 C Average atomic mass of C is 12.01 amu Mass number is for one atom Listed as a decimal on the periodic table

40. Nuclear Symbol

41. Hyphen notation Li - 7

43. Today’s Objectives Review History of the atom Review the following –Know the name, location, charge, and relative mass of each of the subatomic particles in an atom –Know that the atomic number is the number of protons in the nucleus of an atom, and is unique to each element. –Understand that isotopes are atoms of the same element that differ in the number of neutrons in the nucleus, and therefore differ in mass. –Know the mass number is, and be able to use it to correctly designate isotopes using both hyphen notation and nuclear symbols Know the difference between a neutral atom and an ion is the number of electrons, the charge of the ion is the difference between the number of protons and neutrons For any given atom or ion, be able to determine the number of each subatomic particles.

44. IONS Same number of protons but a different number of electrons Charged particles because the number of electrons (-) is either greater than or less than the number of protons (+) H + Ions are determined by there place on the periodic table.

45. Practice Determine the number of subatomic particles for the following: –He –C -14 –Na + –O -2

46. Nuclear Reactions Nuclear reactions involve the nucleus of the atom Radioactivity is the spontaneous emission of radiation from an atom Nuclear reactions change elements involved

47. Alpha Particle Alpha particle –Helium nucleus with no electrons –Will bounce off of paper and skin –+2 charge

49. Beta Particle Beta particle –High energy electron –Come from the decay of a neutrons –Will penetrate skin –Blocked by aluminum and Plexiglass –-1 charge

51. Gamma Rays –High energy wave –No charge –No mass –Penetrates skin, damages cells and mutates DNA –Blocked by lead Gamma Radiation

53. Nuclear Stability Most elements have a stable nucleus A strong nuclear force holds protons and neutrons together Neutrons act as the “glue” holding the protons together

55. Nuclear Equations Scientists use a nuclear equation when describing radioactive decay The mass number and atomic number must add up to be the same on both sides of the equation

56. Beta Decay Beta decay results in an increase in the atomic number

57. Practice Write the nuclear equation of the alpha decay of Radon – 226 Write the nuclear equation of the alpha decay of Gold - 185

58. Practice Write the nuclear equation of the beta decay of Iodine - 131 Write the nuclear equation of the beta decay of Sodium - 24

59. Chapter 24 Applications of Nuclear Chemistry

60. Half Life Radioisotopes are radioactive isotopes of elements (not all isotopes are radioactive) A half-life is the amount of time it takes for one half of a sample to decay. http://lectureonline.cl.msu.edu/~mmp/applist/de cay/decay.htmhttp://lectureonline.cl.msu.edu/~mmp/applist/de cay/decay.htm

61. Beta Decay of Phosphorous - 32

62. Radiocarbon Dating Carbon - 14 undergoes beta decay Half life of 5,730 years Used to approximate ages 100 – 30,000 years Other radioisotopes are used to measure longer periods of time

63. ParentDaughterHalf Change in... Carbon-14 Nitrogen-145730 years Uranium-235Lead-207704 million years Uranium-238Lead-2064,470 million years Potassium-40Argon-401,280 million years Thorium-232Lead-20814,010 million years Rubidium-87Strontium-8748,800 million years

64. Nuclear Bombardment Nuclear scientists make nuclei unstable by being bombarded with particles Also known as particle accelerators or “atom smashers”

67. Radiation SI units are in Curies (Ci) One Curies is amount of nuclear disintegrations per second from one gram of radium Also measured in rem (Roentgen equivalent for man Over 1000 rem is fatal Detected by a Geiger counter

69. Nuclear Power Nuclear Reactors use fission of Uranium-235 as source of energy A large nucleus is split into two smaller nuclei A small amount of mass is converted to a tremendous amount of energy ~1 lb Uranium 235 = 1 million gallons of gasoline http://people.howstuffworks.com/nuclear- power2.htmhttp://people.howstuffworks.com/nuclear- power2.htm

73. Nuclear Fusion 2 atomic nuclei fuse releasing a tremendous amount of energy

75. Nuclear Weapons Source of energy is Plutonium or Hydrogen Can be fusion or fission

76. Gun-triggered fission bomb (Little Boy - Hiroshima), Implosion-triggered fission bomb (Fat Man - Nagasaki), http://people.howstuffworks.com/nuclear-bomb5.htm