1. The study of changes to the nucleus of the atom.
Nuclear Chemistry
The study of changes to the nucleus of the atom.

2. The Nucleus Comprised of protons and neutrons (nucleons).
# protons = atomic number.
# protons + neutrons = mass number

3. Isotope Review Isotope:
Atoms of same element with different numbers of neutrons.
Have different levels of “abundance” in nature.
Some isotopes or “nuclides” of an element can be unstable, or “radioactive”.
Example of Carbon Isotopes
Note:
We will be talking about isotopes very specifically in this unit.
We will not be using the average atomic mass you see on the Ref tables.

4. What is Radioactivity?
Radioactivity: the “decay” of the nucleus by emitting particles and/or energy in order to become more stable.

5. What Causes an Isotope to be Radioactive and Decay?
Proton : Neutron
ratio in nucleus

6. Neutron-Proton Ratios
Positive protons in the nucleus repel each other.
Neutrons play a key role stabilizing the nucleus.

7. Neutron-Proton Ratios
For smaller nuclei (atomic # below 20) stable nuclei have a neutron-to-proton ratio close to 1:1.

8. Neutron-Proton Ratios
As nuclei get larger, it takes a greater number of neutrons to stabilize the nucleus.
There are no stable nuclei
with an atomic number
greater than 83.

9. Early Pioneers in Radioactivity
Rutherford:
Discoverer Alpha and Beta rays 1897
Roentgen:
Discoverer of X-rays 1895
The Curies:
Discoverers of Radium and Polonium
Becquerel:
Discoverer of Radioactivity 1896
Marie Curie 3 parts 7 minutes each

10. RUTHERFORD DISCOVERS DIFFERENT TYPES OF RADIATION
Ernest Rutherford discovered three types of radioactive emissions by using a magnetic field.

11. Reference Table O Top # = mass Bottom # = charge
Shows the symbols of some of the different particles used in nuclear chemistry.
Top # = mass
Bottom # = charge

12. Types of Radioactive Decay
Cloud Chamber:

13. Alpha Decay
An -particle is emitted (basically a helium nucleus) He 4 2 U
238 92
 Th
234 90 He 4 2 +

14. Heaviest type of emission
Mass of 4
Charge of +2

15. Beta Decay
A - particle is emitted (a high energy electron) - −1 e or I
131 53 Xe 54
 + e −1

16. Wait a tic How does a nucleus give off an electron!
Neutron splits into a proton and electron.
n → p e-
Proton stays behind and electron shoots out of nucleus.

17. e C B e Positron Emission
A positron is emitted (a particle that has the same mass as but opposite charge than an electron) e +1 C 11 6
 B 5 + e +1

18. Positrons are a type of “antimatter”.
Quickly destroyed as soon as they come in contact with an electron.

19. Gamma Emission
High-energy radiation that almost always accompanies the loss of a nuclear particle.
It is NOT a particle, it is pure energy.
No mass or charge.
Not affected by a magnetic field. 

20. p e n Electron Capture + An electron close to nucleus get “captured’.
It combines with a
proton to make a neutron. p 1 + e −1
 n

21. Penetrating Power
Penetrating Power: how far radiation can travel through material.
Protection requires different degrees of shielding.
Alpha – paper or skin
Beta – aluminum foil
Gamma – thick lead

22. Ionizing Ability
Ionizing Ability: how well radiation strips electrons from other atoms and molecules creating ions.
Can cause mutations, and cell destruction
Alpha - Highest
Beta - Middle
Gamma – Low

23. Damage to Cells
Because of high ionizing ability, Alpha and Beta cause most damage inside the human body.
Gamma rays are less ionizing but protection against gammas requires thicker shielding.

24. Measuring Radioactivity
One can use a device like a Geiger counter to measure the amount of activity present in a radioactive sample.

25. Natural Transmutation (Decay)
“Spontaneous” transmutation of a radioisotope into another element.
Doesn’t require the input of outside energy.
Occurs at a specific rate that we can measure. (Half Life)

26. Radioactive Series
Decay Series: very large radioactive nuclei undergo a “series” of decays until they form a stable nuclide (often a nuclide of lead).

27. Artificial Transmutation
The change of one element to another artificially by bombarding it with other particles.
These equations always have 2 reactants on the left (as opposed to natural decay)
Artificial Transmutation
Natural Transmutation

28. How do We Bombard Nuclei?
Particle Accelerators:
Speed up charged particles
in a magnetic field to collide
with nuclei
Neutrons and gamma radiation
can’t be accelerated as they
have no charge!

29. Transuranium Elements:
Elements “beyond” uranium (largest natural element)
Atomic numbers greater than 92
Artificially created through nuclear bombardment

30. The Science Show: 4 New Elements added to Periodic Table
Video: Islands of Stability

31. Typical Particle Accelerator
Enormous, with circular tracks with radii that are miles long.

32. Brookhaven Accelerator

33. Balancing Nuclear Equations
Mass and charge are “conserved”
Balance so that the mass (top #’s) and charge (bottom #’s) equal each other.

34. Typical Test Questions

36. Half Life Amount of time for half a radioactive sample to decay.
Length of a half life cannot be changed.
Ranges from milliseconds to billions of years.
(See Table N)
Radioactivity decreases with time.

37. Radioactive Dating Rate of decay is constant over time.
Measure amount of radioisotope remaining in sample to determine age.
C-14 is used to date organic material up to 60,000 years old.
U-238 is used to date extremely old geological formations
Carbon 14 Dating:n (2 minutes)

38. Reference Table N
Decay mode: type of particle emitted by natural decay
Half Life: length of time for “half” of the atoms in a sample to undergo natural decay.

39. Half Life Basic Formula: # Half Lives = Total Time Elapsed
Time of One Half Life (t1/2 )

40. Half Life Problem
Ex: If 500 grams of I-131, t1/2 = 8 days, decays for 32 days, how much would remain?
32 days = 4 half lives
8 days
500 g → 250 g→ 125 g → 62.5 g→ grams

41. Half Life Problem
Ex: If 300g of a radioisotope decays to g in 120 days, what is the t1/2 ?
300 → 150 → 75 → 37.5g
3 half lives
3 half lives = 120 days t1/2 = 40 days
t1/2

42. Half Life Problem 1 → ½ → ¼ → 1/8
Ex: What fraction of a sample of I remains after 24 days of decay?
t1/2 = 8 days
24 days = 3 half lives
8 days
Start End
1 → ½ → ¼ → 1/8

43. Half Life Problem
Ex: If 60 g of N-16 remains in a sample. How many grams were present 28 seconds ago?
t1/2 = 7 sec.
28 sec = 4 half lives AGO
7 sec
We double going back in time
60 → 120 → 240 → 480 → 960 grams

44. After 32 days, 5 milligrams of an
After 32 days, 5 milligrams of an 80-milligram sample of a radioactive isotope remains unchanged.
What is the half-life of this element?
(1) 8 days     
(2) 2 days  
(3) 16 days (4) 4 days

45. An original sample of K-40 has a mass of 25. 00 grams. After 3
An original sample of K-40 has a mass of grams. After 3.9 × 109years, grams of the original sample remains unchanged.
What is the half-life of K-40?
(1) 1.3 × 109 y    
(2) 2.6 × 109 y    
(3) 3.9 × 109 y (4) 1.2 × 1010 y

46. What is the half-life of sodium-25 if 1. 00 gram of a 16
What is the half-life of sodium-25 if 1.00 gram of a gram sample of sodium-25 remains unchanged after 237 seconds?
(1) 47.4 s    
(2) 79.0 s (3) 59.3 s    
(4) 118 s

47. How many days are required for 200. grams of radon-222 to decay to 50
How many days are required for 200. grams of radon-222 to decay to 50.0 grams?
(1) 1.91 days       
(2) 3.82 days  
(3) 7.64 days         
(4) 11.5 days

48. Honors Half Life Equations
Radioisotopes each have a unique half-life.
Each will decay at a specific “rate” over time.
Use the rate constant “k” to denote a specific rate constant for an isotope in half-life problems.
k = .693
t1/2

49. log N0 = k x t N 2.3 N0 = original quantity N = final quanity
t = total time
k = decay constant (.693)
t1/2

50. Half Life Graph
Use the graph to see how much time it takes for half the nuclei to decay

52. Energy in Nuclear Reactions
Nuclear reactions yield more energy than chemical reactions
When changes happen to the nucleus, some matter is converted to energy.
Einstein’s famous equation,
E = mc2, allows us to calculate this energy.

53. Energy in Nuclear Reactions
E = energy in Joules
m = mass (lost) in kilograms
c = the speed of light (3 x 108 meters/sec)

54. Energy in Nuclear Reactions
Ex: The mass change for the decay of
1 mole of uranium-238 is g.
The change in energy, E, is then
E = (m) c2
E = (4.6  10−6 kg)(3.00  108 m/s)2
E = 4.1  1011 Joules

55. Mass Defect (Honors)
The difference between the mass of an atom and the sum of the masses of the individual protons and neutrons in it’s nucleus.
The "vanishing" mass of the protons and neutrons is converted to energy.

56. Nuclear Fission = Splitting the Nucleus
Fission and Fusion: 5 minutes

57. Nuclear Fission
Large nuclei are split (basically in half), making various “fission products” & large amounts of energy.
Mass after splitting is less than you started with.
Matter is converted to energy.

58. Recognize this Reaction

59. Nuclear Chain Reaction:
Bombard nuclide with a neutron.
Nuclei split releasing more neutrons that strike other nuclei, and so on and so on....

60. Critical Mass: minimum amount of fissionable
material present for the chain reaction to be sustained.

61. Controlled vs. Uncontrolled Fission
Controlled Chain Reaction: occurs in nuclear reactors or power plants.
Some of the free neutrons are removed
Uncontrolled Chain Reaction: occurs in nuclear bombs or “atomic bombs”.
Video Clip:
Uncontrolled Fission (mouse traps)
Simple animation 1:00

62. Nuclear Power Plants

63. Nuclear Reactor
Generates heat through controlled nuclear fission to produce steam that turns a turbine connected to an electric generator.
Nuclear Reactors (5 minutes)

64. Major Parts of a Nuclear Reactor
Fuel Rods:
Contain a fissionable isotope
Surrounded by coolant in reactor core
Enriched U-235, Pu-239
Moderator:
Slows down neutrons to increase chances for fission.
Graphite, water, or heavy water
Control Rods:
Absorb excess neutrons
Control rate of chain reaction
Can be raised and lowered
Boron or Cadmium

65. Neutron Moderation and Absorption
Bang Goes the Theory (3.5 min)

66. Coolant: Shielding: Heat Exchanger: Turbine:
Stops core from overheating
Transfers heat to heat exchanger
Water, air, heavy water
Shielding:
Steel reinforced concrete to protect workers from radiation
Heat Exchanger:
Heat from fission is transferred to water which turns to steam
Turbine:
Steam generates electricity

67. Breeder Reactors
Use U-238, a nonfissionable but much more plentiful isotope of uranium (99%).
It undergoes transmutation into Pu-239 a fissionable isotope of plutonium

68. Nuclear Power supplies about 20% of the country’s electric power

69. Pros of Using Nuclear Power
What is positive about using nuclear fission as a source of energy?

70. Large amount of energy from very small quantity of fuel.

71. No greenhouse gas is produced (CO2)

72. Less reliance on foreign countries for fuel.

73. Cons of Using Nuclear Power
What are some of the negative aspects of using nuclear fission as a source of energy?

74. Effects of Radiation Exposure
Somatic Effects:
Kills body cells or makes them cancerous.
“Radiation sickness” (hair falls out, nausea, fatigue, radiation “burns”)
Genetic Effects:
Mutations in eggs, sperm increase chance of mutations in next generation.

75. Chemical properties of radioisotopes are the
**IMPORTANT **
Chemical properties of radioisotopes are the
same as nonradioactive. Form bonds the same way.
Why?
They have same electron configurations and valence shells.
Can get incorporated into bone, tissue, organs and eventually cause mutations and cancer.
Ex: Sr-90 is chemically similar to Calcium
Ex: Radium Girls: Watch Dial Painters
Hank Green (4:38)
The story of Radium (10 minutes)

76. Long-term Storage of Radioactive Wastes

77. Since the 1940s, the United States has generated over 75,000 metric tons of spent nuclear fuel and high-level nuclear waste at 80 sites in 35 states.
That’s enough to fill
a football field about
15 feet deep.
Nuclear waste is expected to increase by about 2,000 metric tons per year, more than doubling to 153,000 metric tons by 2055.

78. The closest we’ve come to a long term nuclear-waste storage has been Yucca Mountain: a “geological repository,” site about 100 miles Northwest of Las Vegas.

79. Nuclear Reactor Malfunctions

80. Three Mile Island,
PA (1979)
Worst accident in U.S. nuclear power plant history.
Released moderate amounts of radioactive gases into the environment

81. Chernobyl, Ukraine (1986) Video: http://youtu.be/BfKm0XXfiis
Chernobyl: 11 min PBS

82. Fukashima,
Japan (2011)
Fukashima revisted:
“Nuclear Boy Cartoon”
Bang Goes the Theory (2 min)

83. Nuclear Fusion = Joining Nuclei Together

84. Nuclear Fusion
Nuclear Fusion: the joining together of smaller nuclei to make larger ones.

85. Recognize this Type of Equation

86. Fission Vs. Fusion

87. It’s Really Hard to do!
Due to the repulsive forces between positive nuclei, this requires extremely high temp. and pressures.

88. Stars = Fusion Reactors
Stars generate energy through fusion.
All elements in the universe were formed through the process of fusion.
Video: How elements are formed 5 minutes

89. Nuclear Fusion Pros Produces more energy than fission.
Fuel (hydrogen) is plentiful
No radioactive waste
Fission vs Fusion 2 minutes

90. High temp./pressure needed to initiate.
Cons
High temp./pressure needed to initiate.
Material must be in the plasma state at several million Kelvin.
No fusion reactors exist, still in research stage.
Nuclear Fusion 7:55 min

91. Nuclear Fusion Reactor?
Tokamak apparati like the one shown at the right show promise for carrying out these reactions.
They use magnetic fields to heat the material.
Recent Headline

92. Hydrogen “Fusion” Bomb
Thermonuclear Bomb:
A fission bomb explodes, providing the heat and pressure necessary for fusion to occur.
Much more destructive than an atomic “fission” bomb
Otherwise known as “Dabomb”

93. Uses of Radiation
There are many activities in our everyday lives that would be impossible without the use of radiation or radioactive materials.

94. Dating Materials Half Lives don’t change!
Carbon-14: date organic materials
Uranium-238: date extremely old geological formations (very long half life)

95. Non-Invasive Body Imaging
Radioactive
material injected
Radiation detected
to give image
Used to:
Locate tumors
Determine organ
function
Radioisotopes give doctors the ability to "look" inside the body and observe soft tissues and organs, in a manner similar to the way x-rays provide images of bones.
To detect problems within a body organ, doctors use radiopharmaceuticals or radioactive drugs. Radioisotopes that have short half lives are preferred for use in these drugs to minimize the radiation dose to the patient. In most cases, these short-lived radioisotopes decay to stable elements within minutes, hours, or days, allowing patients to be released from the hospital in a relatively short time. Radioisotopes carried in the blood allow doctors to detect clogged arteries or check the functioning of the circulatory system. Some chemical compounds concentrate naturally in specific organs or tissues in the body. For example, iodine collects in the thyroid while various compounds of technetium-99m* (Tc-99m) collect in the bones, heart, and other organs. Taking advantage of this proclivity, doctors can use radioisotopes of these elements as tracers. A radioactive tracer is chemically attached to a compound that will concentrate naturally in an organ or tissue so that a picture can be taken. The process of attaching a radioisotope to a chemical compound is called labeling. Technetium-99m is used in more than 80% of the cases.
(The Regulation and Use Of Radioisotopes in Today's World -NUREG/BR-0217)

96. Cancer Treatment
Direct external radiation beam at tumor, usually from Co-60 gamma radiation.
Internally deposit “seeds” containing radioactive materials near tumor site.
Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the target tissue). Internal radiotherapy involves placing radioactive implants directly into a tumor or body cavity, e.g., brachytherapy.
Criteria for internally deposited radioisotopes:
the half-life should not cause an extended stay in the hospital
radioisotope should emit particulate radiation (alphas or betas)
radioisotope should also emit gamma rays to determine that the appropriate region has been targeted
External beam radiotherapy refers to the process of focusing photons such as X-rays or gamma rays onto cancer located on the surface of the body, or inside the body. The same property that makes radiation hazardous can also make it useful in helping the body heal. When living tissue is exposed to high levels of radiation, cells can be destroyed or damaged so they can neither reproduce nor continue their normal functions. For this reason radioisotopes are used in the treatment of cancer (which amounts to uncontrolled cell division). Although some healthy tissue surrounding a tumor may be damaged during the treatment, mostly cancerous tissue can be targeted for destruction.
A device called a teletherapy unit destroys malignant tumors with gamma radiation from a radioisotope such as cobalt-60 (Co-60). Teletherapy units use a high-energy beam of gamma rays to reduce or eradicate tumors deep within the body. These units are licensed by the NRC because they use byproduct material that is produced only by a nuclear reactor. (The Regulation and Use Of Radioisotopes in Today's World -NUREG/BR-0217)

97. Important!!!
Isotopes used in medical diagnosis and treatment should always have:
SHORT HALF LIVES
BE QUICKLY ELIMINATED FROM THE BODY

98. Some Isotopes Used in Medicine Important.
I-131: treat and diagnosis thyroid disorders
Co-60: emits gamma radiation to treat cancer
Tc-99: treats brain tumors
Th-201: useful to study damage to the heart

99. Tracers:
Radioisotopes react chemically the same way as nonradioactive (same # valence electrons).
Use them to “trace” the path of a chemical through the body or through a chemical reaction mechanism.
Ex: C-14, P-32, O-18
Radioisotopes of a chemical element behave in the same manner as a stable, non-radioactive element. Many radioactive forms of the stable elements essential to life are used in research for molecular biology and human genetics for example phosphorus 33, phosphorus 32 and carbon 14.
Radioisotopes are used as a research tool to develop new strains of food crops that are more
resistant to disease, are of higher quality, allow earlier ripening, and produce a higher yield.
Radioisotope-powered electrical generators have been used to power exploration space craft, navigational, weather, and communication satellites. They allow us to operate weather stations at the North and South Poles, seismic sensing stations in remote locations, and devices placed on the ocean floor for scientific investigations and
national defense. (The Regulation and Use Of Radioisotopes in Today's World
(NUREG/BR-0217)
Clinical research has been designed to address the disposition of drugs in hair, saliva, liquid perspiration, plasma, blood and urine. Other research interests include the development of sensitive and accurate methods for the screening of drugs and the analysis of drugs of abuse in humans.

100. Sterilization: Gamma rays kill bacteria, mold, fungus on surface.
Medical instruments
Food (ground beef, strawberries, etc.)
gives food a longer shelf-life
prevents E-coli outbreaks
Controls sprouting
Does not make the food radioactive
FDA Approved
How Does food Irradiation work? (6 min)
Using Nuclear Science is Food Preservation (3 min)
Radioisotopes are used in many of today's industrial processes. High-tech methods that ensure the quality of manufactured products often rely on radiation generated by radioisotopes. To determine whether a well drilled deep into the ground has the potential for producing oil, geologists use nuclear well-logging, a technique that employs radiation from a radioisotope inside the well to detect the presence of different materials. Radioisotopes are also used to sterilize instruments; to find flaws in critical steel parts and welds that go into automobiles and modem buildings; to authenticate valuable works of art; and to solve crimes by spotting trace elements of poison, for example. Radioisotopes can also eliminate dust from film and compact discs as well as static electricity (which may create a fire hazard) from can labels. (The Regulation and Use Of Radioisotopes in Today's World - NUREG/BR-0217)

102. Spacecraft Power Supplies
Have allowed space craft to explore the outer solar system, too far from the sun for solar panels to be effective
Spacecraft power (3 min)

103. Crash Course Chemistry
Bill Nye: Nuclear Energy (25 minutes)
Nuclear Chem Part 1
Fission and Fusion
Chernobyl: 11 min PBS