Unit 14: The Periodic Table and Nuclear Chemistry

1
Unit 14 The Periodic Table andNuclear Chemistry

• Tyna L. Meeks

2
The Periodic Table

• Every substance has characteristic properties
  that distinguish it from other substances, thus
  allowing it to be identified
• PHYSICAL PROPERTIES
• Physical changes are changes that occur without
  altering the identity of the substance in any
  way.

3
The Periodic Table

• Every substance has the potential to be combined
  with another substance to form a brand new
  substance
• CHEMICAL PROPERTIES
• Chemical changes will always create a new
  substance. Chemical changes can often be
  detected by the formation of a gas, solid, color
  change, a change on the surface, or temperature
  change

4
The Periodic Table

• Vocab Review
• Atom Element
• Electron Compound
• Ion Molecule
• Neutron Nucleus
• Proton

5
Topic 1 The Atom

• The Pattern of Atomic Numbers
• Shortcut 12C 14C
• 6 6

6
Topic 1 The Atom

• What else is in the box? 12.0 C 4
• 6
• 2-4

7
The Periodic Table

• When considering an atom, keep this in mind
• number of protons must equal number of electrons
  (atoms are neutral after all)
• number of neutrons can vary
• if you have two atoms of the same element, they
  must have the same atomic number but different
  mass numbers ISOTOPES

8
The Periodic Table

• The number of protons, called the ATOMIC NUMBER,
  distinguishes atoms of different elements.
• The atomic number identifies every atom as a
  particular element.
• BUT, the atomic number is not the atomic weight.

9
The Periodic Table

• There is another particle in the atom that is
  neutral, but has mass. This particle is called a
  NEUTRON!
• Located in the nucleus
• All mass of atom is in nucleus
• Nucleus is made up of protons and neutrons
  ONLY!!!
• Atomic weight is equal to the average of all
  known isotopes

10
The Periodic Table

• Valence electrons
• Electrons in the highest principal energy levels
  are the electrons that can be used for bonding
• arranged around the symbol of the element to
  easily identify bonding electrons
• this symbol arrangement is called the Lewis Dot
  Structure

11
The Periodic Table

• One element differs from another because its
  atoms have properties that differ from those of
  all other elements.
• Elements can be grouped, or classified, in
  several ways according to similarities and
  differences in their properties.

12
The Periodic Table

• In an effort to impose some organization on the
  information related to the elements, several
  scientists tried to place elements with similar
  properties near one another in a chart.
• - atomic weight
• - combining capacity

13
The Periodic Table
14
The Periodic Table
Original Periodic Law - atomic mass -
reactivity with oxygen Modern Periodic Law -
atomic number
15
The Periodic Table

• Similar chemicals were placed in vertical columns
  (GROUPS)
• Horizontal arrangements were done based on atomic
  weight (PERIODS)

16
The Periodic Table
17
The Periodic Table
Know the names of these following
groups Alkali Metals Alkaline Earth
Metals Transition Metals Chalcogens Halogens N
oble Gases
18
The Periodic Table

• Simplest classification?
• Metal, Nonmetal, or Metalloid

19
The Periodic Table

• Simplest classification?
• Metal Nonmetal Metalloid
• malleable brittle both
• ductile mostly gases
• luster lack luster, dull
• conductors non-conductors
• mostly solids

20
The Periodic Table

• Simplest classification?
• Metal Nonmetal
• higher densities lower densities
• lose electrons gain electrons
• to form () to form (-)
• ions that are ions that are
• smaller than larger than
• atom atom

21
The Periodic Table

• Special cases?
• Transition Metals Noble Gases
• d block Group 18
• create colored completely
• solutions unreactive

22
The Periodic Table

• Homework pg 83-85, ques. 1-29

23
The Periodic Table

• Homework pg 83-85, ques. 1-29
• 1. 1 9. 3 17. 3 25. 3
• 2. 2 10. 1 18. 3 26. 3
• 3. 2 11. 1 19. 1 27. 2
• 4. 4 12. 4 20. 4 28. 4
• 5. 2 13. 3 21. 3 29. 2
• 6. 2 14. 3 22. 1
• 7. 4 15. 1 23. 3
• 8. 2 16. 4 24. 3

24
The Periodic Table

• Atomic Size Atomic Radius
• Size of an atom is due to two things
• Number of electron shells
• Number of protons the atom has if its in the
  same shell

25
The Periodic Table

• Atomic Size Atomic Radius
• 1. As you go up or down the group, the size
  changes based on the number of electron shells
• - down the group, size gets bigger, because
  youve added electron shells
• - up the group, size gets smaller, because
  youre losing electron shells

26
The Periodic Table

• Atomic Size Atomic Radius
• 2. As you go across the SAME period, the size
  changes based on the number of protons in the
  nucleus
• - more protons smaller atom
• moving to the right
• - less protons bigger atom
• moving to the left

27
The Periodic Table

• Ionization Energies Energy needed to LOSE
  an electron
• Ionization Energy is due to one thing
• 1. the bigger an metallic atom is the easier it
  is to give away the farthest, outermost, electron

28
The Periodic Table

• Lets think about it
• the more energy needed to force an atom to lose
  an electron, the less the atom wants to lose the
  electron
• who wants to lose electrons?
• how much energy do they charge?

29
The Periodic Table

• Think, the fewer valence electrons a metal has,
  the easier it is to give them away
• Group 1 has the fewest electrons, and therefore
  charges the least ionization energy
• Group 18 has a full shell and cannot afford to
  lose any electrons so they charge the highest
  ionization energy
• Goes from METALLIC to NONMETALLIC

30
The Periodic Table

• 1. the bigger a metallic atom is, the easier it
  is to give away the farthest, outermost, electron
• The largest atom in a group is at the bottom
• Larger atoms charge less energy to remove the
  outermost electron
• Ionization energies decrease as you go down the
  group

31
The Periodic Table

• As you go down a group
• Atom size INCREASES
• Ionization energy DECREASES

32
The Periodic Table

• As you go across a period
• Atom size DECREASES
• Ionization energy INCREASES

33
The Periodic Table

• Electronegativities ability to attract an
  electron
• Electronegativity is due to one thing
• 1. the bigger an atom is the harder it is to
  attract an electron towards the nucleus

34
The Periodic Table

• Lets think about it
• who wants to gain electrons?
• How badly do they want the electrons?
• If both atoms want to gain an electron, the atom
  who wants it more holds it closer to its nuclear
  charge, creating a polar bond

35
The Periodic Table

• Think, the smaller the atom is, the higher its
  nuclear charge is
• Group 18 has a full shell, and is not interested
  in attracting any electrons, even though it is
  the smallest
• Group 17 has an almost full shell and is the next
  smallest in size, therefore creating the highest
  attractive force
• Group 1 has a nearly empty shell, not interested
  in attracting any electrons, and is the largest
  in the period
• Goes from NONMETALLIC to METALLIC

36
The Periodic Table

• 1. the smaller an atom is, the easier it is to
  attract an electron
• The smallest atom in a group is at the top
• Smaller atoms attract electrons easier than
  larger atoms
• Electronegativities decrease as you go down the
  group

37
The Periodic Table

• As you go down a group
• Atom size INCREASES
• Electronegativity DECREASES

38
The Periodic Table

• As you go across a period
• Atom size DECREASES
• Electronegativity INCREASES

39
The Periodic Table

• Allotropes
• two or more forms of the same element that have
  distinctly different physical and chemical
  properties
• O2 and O3 oxygen and ozone respectively
• white phosphorous vs. red phosphorous

40
The Periodic Table

• Allotropes
• carbon also exists in three allotropic forms

41
The Periodic Table

• Homework pg 73-75, ques. 30-90 even

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The Periodic Table

• Homework pg 73-75, ques. 30-90 even
• 30. 4 38. 2 46. 2 54. 3
• 31. 39. 47. 55.
• 32. 3 40. 4 48. 4 56. 2
• 33. 41. 49. 57.
• 34. 1 42. 1 50. 1 58. 3
• 35. 43. 51. 59.
• 36. 4 44. 2 52. 4 60. 1
• 37. 45. 53. 61.

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The Periodic Table

• Homework pg 73-75, ques. 30-90 even
• 62. 3 70. 1
• 63. 71.
• 64. 1 72. 3
• 65. 73.
• 66. 1 74. 2
• 67. 75.
• 68. 2 76. Na has more protons, which
• 69. makes it smaller

44
The Periodic Table

• Homework pg 73-75, ques. 30-90 even
• 78. Atomic number defines the element, not mass,
  using mass causes error
• 80. MBr3 M2O3 valence e-
• 82. smallest C largest Al
• highest IE C lowest IE Al

45
The Periodic Table

• Homework pg 73-75, ques. 30-90 even
• 84. Metals on left move towards nonmetals on the
  right, going through metalloids which have both
  characteristics, to the noble gases which have
  full shells
• 86. It only has 1 electron to lose before it
  gets a stable octet
• 88. MgX2
• 90. I and Te Ni and Co

46
Nuclear Chemistry

• The Great Discovery
• Models of the atoms took off during the
  investigations involving radiation
• fluorescence
• cathode rays
• x-rays

47
Nuclear Chemistry

• The Great Discovery
• Cathode Rays

48
Nuclear Chemistry

• The Great Discovery
• X-rays

49
Nuclear Chemistry

• The Great Discovery
• Becquerels mistake

50
Nuclear Chemistry

• Nuclear Radiation
• Gamma pure energy, highest form of energy on
  electromagnetic spectrum

51
Nuclear Chemistry

• Nuclear Radiation
• All radiation can be classified two ways,
  ionizing and nonionizing
• Nonionizing radiation is very low in energy-
  transfers its energy to matter causing the atoms
  to vibrate or move the electrons to higher energy
  states

52
Nuclear Chemistry

• Nuclear Radiation
• All radiation can be classified two ways,
  ionizing and nonionizing
• Ionizing radiation is very high in energy-
  includes all nuclear reactions, the amount of
  energy found here is enough to eject an electron
  completely from its atom

53
Nuclear Chemistry

• Nuclear Radiation
• Nuclear Radiation is a form of ionizing radiation
  that results in changes in the nuclei of atoms
• Most atoms are stable and their nuclei do not
  change (transmutate)
• - Unstable nuclei are created by unbalanced
  proportions of neutrons to protons in nucleus

54
Nuclear Chemistry

• Nuclear Radiation
• These unstable nuclei undergo changes to become
  stable, and eject particles from the nucleus to
  get to a stable proportion
• Three types of radiation are normal
• ALPHA
• BETA
• GAMMA

55
Nuclear Chemistry

• Nuclear Radiation ( Table O)
• Alpha a helium nucleus composed of two protons
  and two neutrons 4He2
• Beta a high speed electron 0e-1
• Positron a high speed positively charge
  electron 0e1
• Neutron alters mass, not charge 1n0
• Gamma pure energy 0g0

56
Nuclear Chemistry

• Nuclear Radiation
• Forms of energy can be separated using magnetic
  and electric fields

57
Nuclear Chemistry

• Architecture of Atoms
• Review
• nucleus has two particles (nucleons)
• neutron, neutral charge
• proton, positive charge
• electrons have 1/1826 the mass of a proton
• negative charge

58
Nuclear Chemistry

• Architecture of Atoms
• Review
• atomic notation 14
  C 6

59
Nuclear Chemistry

• Isotopes in Nature
• All atoms have the ability to have varying
  amounts of neutrons
• ISOTOPES
• The atomic mass listed on periodic table is an
  average weight of all isotopes of the element
  found in nature

60
Nuclear Chemistry

• Isotopes in Nature
• To calculate atomic weights, multiply each weight
  of the atom by the percent it is found in nature.
  Add all your fractions together, and divide by
  100...

61
Nuclear Chemistry

• Isotopes in Nature
• If Carbon is found in nature 98.89 as C-12, and
  1.108 as C-13, what is the average weight?

62
Nuclear Chemistry

• Isotopes in Nature
• If Carbon is found in nature 98.89 as C-12, and
  1.108 as C-13, what is the average weight?
• 98.89 12 amu 1186.68

63
Nuclear Chemistry

• Isotopes in Nature
• If Carbon is found in nature 98.89 as C-12, and
  1.108 as C-13, what is the average weight?
• 98.89 12 amu 1186.68
• 1.108 13 amu 14.404

64
Nuclear Chemistry

• Isotopes in Nature
• If Carbon is found in nature 98.89 as C-12, and
  1.108 as C-13, what is the average weight?
• 98.89 12 amu 1186.68
• 1.108 13 amu 14.404
• 100 1201.084

65
Nuclear Chemistry

• Isotopes in Nature
• If Carbon is found in nature 98.89 as C-12, and
  1.108 as C-13, what is the average weight?
• 98.89 12 amu 1186.68
• 1.108 13 amu 14.404
• 100 1201.084
• Avg 12.011 amu

66
Nuclear Chemistry

• Radioisotopes
• For any element, an isotope that is unstable DUE
  TO PROPORTIONS OF PROTONS AND NEUTRONS and is
  radioactive is called a radioisotope

67
Nuclear Chemistry

• Belt of Stability

68
Nuclear Chemistry

• Exposure to Ionizing Radiation
• If the atom isnt on the chart, stops at atomic
  number 82, then the proportions are so off huge
  particles need to be emitted
• the most mass is ejected when a helium nucleus is
  split off, two protons and two neutrons leave
• decrease atomic number by 2, mass number by 4
• ALPHA emission

69
Nuclear Chemistry

• Exposure to Ionizing Radiation
• If the atom is too high, above the belt, then too
  many neutrons exist in the atom
• the atom needs to lose neutrons
• the neutron splits itself into a proton and an
  electron, keeps the proton and shoots out the
  electron
• atomic number goes up by 1, mass number stays the
  same
• BETA emission

70
Nuclear Chemistry

• Exposure to Ionizing Radiation
• If the atom is too low, below the belt, then too
  many protons exist in the atom
• the atom needs to lose protons
• the proton splits itself into a neutron and a
  positive electron, keeps the neutron and shoots
  out the positron
• atomic number goes down by 1, mass number stays
  the same
• POSITRON emission

71
Nuclear Chemistry

• Exposure to Ionizing Radiation
• Nuclear Equations can help keep track of the
  protons and neutrons for you.
• 1n0 ? 1p1 0e-1 make sure all
  numbers add up left right 1p1 ? 1n0
  0e1

72
Nuclear Chemistry

• Exposure to Ionizing Radiation
• Nuclear Equations can also help you identify the
  new element created.
• 226Ra88 ? X 4He2
• solve numbers left right, look up the atomic
  number you solve for and that is your new element

73
Nuclear Chemistry

• Transmutation change across the nucleus
• Natural ONE reactant, decays to 2 or more
  products
• Artificial TWO reactants, decays to 2 or more
  products

74
Nuclear Chemistry

• Extending the Periodic Table
• 23 transuranium elements (atomic numbers greater
  than 92) have been added
• when a scientist creates a new element that
  stabilizes long enough to take measurements of,
  they get to name it...

75
Nuclear Chemistry

• Transmutations
• Unstable nuclei that decay spontaneously are
  natural transmutations
• Bombarding a nucleus to force it to become
  unstable creates an artificial transmutation

76
Nuclear Chemistry

• Homework pg 178 and 179, 1-23

77
Nuclear Chemistry

• Homework pg 178 and 179, 1-23
• 1. 1 8. 1
• 2. 2 9. 3
• 3. 1 10. 1
• 4. 4 11. 3
• 5. 1 12. 3
• 6. 4 13. 2
• 7. 1 14. 3

78
Nuclear Chemistry

• Homework pg 178 and 179, 1-23
• 15.a) 210Pb82 ? 0e-1 210Bi83
• b) 137Cs55 ? 0e-1 137Ba56
• c) 222Rn86 ? 4He2 218Po84
• d) 185Au79 ? 4He2 181Ir77
• e) 53Fe26 ? 0e1 53Mn25
• f) 37Ca20 ? 0e1 37K19

79
Nuclear Chemistry

• Homework pg 178 and 179, 1-23
• 16. 4 21. 2
• 17. 1 22. 1
• 18. 2 23. 1
• 19. 2
• 20. 1

80
Nuclear Chemistry

• Unleashing Nuclear Forces
• The most famous artificial transmutation is
  nuclear fission.

81
Nuclear Chemistry

• Unleashing Nuclear Forces
• During FISSION, as the atom splits apart, mass is
  lost
• This seems to defy the Conservation of Mass,
  however, Einstein realized that the mass is
  actually converted into energy
• E mc2

82
Nuclear Chemistry

• Unleashing Nuclear Forces
• During FISSION, as the atom splits apart, mass is
  lost
• It takes in incredible amount of force to hold a
  nucleus together remember all protons are
  positively charged and are repelling each other
• Overcoming these forces and splitting one large
  nuclei into 2 smaller nuclei causes the
  conversion of mass into energy

83
Nuclear Chemistry

• Unleashing Nuclear Forces
• 3 neutrons produced by every fission of
  uranium-235.
• Number of fissions and energy released quickly
  escalates exponentially is unchecked
• In order for a fission chain reaction to occur a
  minimum mass of material must be present
  (critical mass) - with minimum present only one
  neutron is effective in producing another fission

84
Nuclear Chemistry
85
Nuclear Chemistry

• Nuclear Reactors
• Uranium is enriched to about 3 U-235 and then
  used to form UO2 pellets that are encased in
  zirconium or stainless steel tubes
• Rods composed of materials such as cadmium or
  boron control the fission process by absorbing
  neutrons
• Called Control Rods
• Moderators slow down neutrons so they can be
  captured more readily by the fuel

86
Nuclear Chemistry

• Nuclear Reactors
• A cooling liquid is circulated through the core
  to carry off heat generated by the nuclear
  fission.
• Cooling liquid and moderator could be one and the
  same substance
• Steam is used to drive a turbine connected to an
  electrical generator, however steam must be
  condensed so additional cooling liquid is
  required, generally acquired from lake or river

87
Nuclear Chemistry

• Nuclear Reactors
• Reactor is surrounded by a concrete shell to
  shield personnel and nearby residents from
  radiation
• Reactor must be stopped periodically so that the
  fuel can be replaced or reprocessed
• Spent fuel rods are being kept in storage at
  reactor sites
• 20 half-lives are required for their
  radioactivity to reach levels acceptable for
  biological exposure (600 years)

88
Nuclear Chemistry

• Nuclear Reactors

89
Nuclear Chemistry

• Nuclear Reactors

90
Nuclear Chemistry

• Nuclear Reactors

91
Nuclear Chemistry

• Nuclear Reactors

92
Nuclear Chemistry

• Nuclear Reactors

93
Nuclear Chemistry

• Nuclear Fusion
• This reaction requires the combining of two
  smaller nuclei to form heavier ones.
• - occurs in our sun
• - 2 hydrogen are fused to form a helium
• 1H1 1H1 --gt 4He2

94
Nuclear Chemistry

• Nuclear Fusion
• appealing as an energy source because of
  availability of light isotopes and because fusion
  products are generally not radioactive
• not presently used to generate energy because
  high energies are needed to overcome the
  repulsion between nuclei
• reaction requires temps of about 40,000,000 K
• these temps have only been achieved using a
  hydrogen bomb

95
Nuclear Chemistry

• Nuclear Fusion

96
Nuclear Chemistry

• Homework pg 180-181, 24-33

97
Nuclear Chemistry

• Homework pg 180-181, 24-33
• 24. 3 30. 2
• 25. 2 31. 2
• 26. 4 32. 1
• 27. 2 33. 1
• 28. 3
• 29. 1

98
Nuclear Chemistry

• Half Lives
• When radioactive substances decay, they do so at
  a CONSTANT RATE
• Each isotope has its own half-life
• Reference Table N

100 50 25 12.5
99
Nuclear Chemistry

• Half Lives
• Most chromium atoms are stable, but Cr-51 is an
  unstable isotope with a half-life of 28 days.
• What fraction of a sample of Cr-51 will remain
  after 168 days?

100
Nuclear Chemistry

• Half Lives
• Most chromium atoms are stable, but Cr-51 is an
  unstable isotope with a half-life of 28 days.
• If a sample of Cr-51 has an original mass of 52.0
  g, what mass will remain after 168 days?

101
Nuclear Chemistry

• Radioisotopes
• in Medicine
• Half Lives
• can be determined
• using a graphical
• analysis of decay

102
Nuclear Chemistry

• Homework pg 183, 34-47

103
Nuclear Chemistry

• Homework pg 183, 34-47
• 34. 3 42. 2
• 35. 1 43. 4
• 36. 2 44. 1
• 37. 3 45. 3
• 38. 4 46. 3
• 39. 2 47. 4
• 40. 4
• 41. 3

104
Nuclear Chemistry

• Exposure to Ionizing Radiation
• Atoms are emitting this radiation to surroundings
  at all times - so your are absorbing radiation
  from your surroundings at all times!!

105
Nuclear Chemistry

• Exposure to Ionizing Radiation
• Some radiation is always naturally
  found in the body

106
Nuclear Chemistry

• How much is safe?

107
Nuclear Chemistry

• Natural radioactive Decay
• Review
• Alpha emission
• Beta emission
• Positron emission
• Nuclear Equations

108
Nuclear Chemistry

• Radon
• Whats all the fuss about?

109
Nuclear Chemistry

• Radiation Detectors
• Geiger counter
• Scintillation counters
• Solid state detectors

110
Nuclear Chemistry

• Radioisotopes in Medicine
• Radioisotopes can be used for several purposes
• Dating
• Chemical Tracers
• Industrial Applications
• Medical Applications

111
Nuclear Chemistry

• Radioisotopes in Medicine
• The length of the half life of a substance can
  help predict certain things
• Geologic dating is done using Uranium
• Biological dating is done using Carbon

112
Nuclear Chemistry

• Due to the constancy of half lives, C14 can be
  used as a molecular clock to determine the ages
  of different objects

Chap. 21.4
113
Nuclear Chemistry

• Shroud of
• Turin - face

114
Nuclear Chemistry

• Shroud of Turin - hands

115
Nuclear Chemistry

• Radioisotopes in Medicine
• When radioactive substances decay, they do so at
  a CONSTANT RATE
• Not dependent on temperature or pressure
• This is a random event, you cannot predict when a
  molecule will begin to decay
• However, you can predict the amount of substance
  that will decay in a given amount of time

116
Nuclear Chemistry

• Radioisotopes in Medicine
• Due to the detectors available, radioisotopes can
  be observed as they go through their chemical
  pathways.
• P-31 is present in fertilizer and can be
  watched as it is taken into the plant

117
Nuclear Chemistry

• Radioisotopes in Medicine
• Due to the detectors available, radioisotopes can
  be observed as they go through their chemical
  pathways.
• C-14 can be used to map metabolic processes as
  it moves through respiration cycles

118
Nuclear Chemistry

• Radioisotopes in Medicine
• All materials absorb radiation in unique ways, so
  strength of material and, and thickness of hidden
  materials can be determined by shooting radiation
  at them.

119
Nuclear Chemistry

• Radioisotopes in Medicine

120
Nuclear Chemistry

• Artificial Radioactivity
• Atoms can be bombarded with particles as well, to
  force them to become unstable and decay
• ARTIFICIAL TRANSMUTATION