Section 18.1
Radioactivity
Objectives
1. Define Radiocarbon Dating and list three items
that have been radiocarbon dated and the
significant findings of the results.
2. Describe, define, draw the 3 water cycles of a
nuclear power generation facility.
3. Describe 3 safety control procedures to help
prevent a nuclear meltdown.
4. Detail the 3 major nuclear reactor “incidents”.
5. List the options for short term and long term
storage or disposal of spent nuclear fuel rods.
Section 18.1
Radioactivity
Objectives
1. To learn the types of radioactive decay
2. To learn to write nuclear equations for
radioactive decay
3. To learn how one element may be
changed to another by particle
bombardment
4. To learn about radiation detection
instruments
5. To understand half-life
Section 18.1
Radioactivity
A Review of Atomic Terms
• nucleons – particles found
in the nucleus of an atom
– protons
– neutrons
• atomic number (Z) –
number of protons in
the nucleus
• mass number (A) – sum of
the number of protons and
neutrons
Section 18.1
Radioactivity
A Review of Atomic Terms
• isotopes – atoms with identical atomic
numbers but different mass numbers
• In other words, the same number of protons,
different # of neutrons
• nuclide – a general term for each unique
atom
• Parent-daughter nuclides -
Section 18.1
Radioactivity
A. Radioactive Decay
• Radiation – general term for energy
• radioactive – nucleus which spontaneously
decomposes forming a different nucleus
and producing one or more particles
• nuclear equation – shows the radioactive
decomposition of an element
Section 18.1
Radioactivity
A. Radioactive Decay
Types of Radioactive Decay
• Alpha Particle – helium nucleus
• Beta negative Particle – electron
• Beta positive Particle
• Gamma Ray – high energy
photon – nucleus does not
change mass # or atomic #
• A  ???? + B
.
• Electron Capture**A + 0-1e  B
4
2He
0 e
-1
0 e
1
0
0
0

-1e
Section 18.1
Radioactivity
A. Radioactive Decay
Radioactive Decay
• Why do these parent nuclides decay?
• The daughter nuclides are more stable-
Section 18.1
Radioactivity
A. Radioactive Decay
Ionizing Radiation has
the potential of altering
DNA…
Blinky
Real
or
not?
Who lives in a
pineapple
under the
sea?
Section 18.1
Radioactivity
Section 18.1
Radioactivity
A. Radioactive Decay
• Alpha-particle production
• Alpha particle – helium nucleus 42He
– Examples
• Net effect is loss of 4 in mass number
and loss of 2 in atomic number.
Section 18.1
Radioactivity
A. Radioactive Decay
• Alpha particle – helium nucleus 42He
– Write the Nuclear Decay Reaction of Ra-226
by alpha emission… 42He
– 22688 Ra 
+ 42He
– What would happen if Rn underwent alpha
decay?
– 22286 Rn 
Section 18.1
Radioactivity
•
•
•
•
•
•
•
•
•
Alpha particle – helium nucleus 42He
Write the Alpha Decay Equation for:
Po-210
210
84 Po 
238
92 U 
230
90 Th 
218
84 Po 
214
84 Po 
Nature of Stability is due to proton arrangement
• Stability predictions related to Mass # and Molar Mass
Section 18.1
Radioactivity
A. Radioactive Decay
• Beta negative-particle production
• Beta particle – electron 0-1e
– Examples
•
• Where does the e- come from??
• Net effect is to change a neutron to a
proton because a neutron is made up of a
proton and electron…
1 n  1 p +
0 e
0
+1
-1
Section 18.1
Radioactivity
A. Radioactive Decay
• Beta neg particle – electron 0-1e
• Write the beta decay equation for:
• 22789 Ac 
+ 0-1e
• 146 C 
•
227
89
Ac 
Section 18.1
Radioactivity
A. Radioactive Decay
• Beta Positive particle (positron) 01e
• Positron – particle with same mass as an
electron but with a positive charge
• Net effect is to change a proton to a neutron.
• Think of the proton as being a neutron
(proton and e-) with an extra positron
Section 18.1
Radioactivity
A. Radioactive Decay
• Positron production 01e
• Write the Positron Production equation for:
• 137 N 
+ 01e
•
38
•
15
8
19
K
O
Section 18.1
Radioactivity
A. Radioactive Decay

0
• Gamma ray release
0
• Gamma ray – high energy photon (energy)
• Net effect is no change in mass number or
atomic number.
• A  A + energy
• Lower energy, more stable
Section 18.1
Radioactivity
A. Radioactive Decay
• Electron capture 0-1e
– Explain this on a subatomic (nucleon) level…
Section 18.1
Radioactivity
A. Radioactive Decay
• Electron capture 0-1e
– When a nucleus grabs an inner orbital e- transforming a
proton to a neutron
– What else is happening in this example?
Section 18.1
Radioactivity
A. Radioactive Decay
• Electron capture 0-1e
• Write the e- capture equation for:
• 7333 As + 0-1e 
•
40
•
137
19
K
57
La
Section 18.1
Radioactivity
A. Radioactive Decay
Section 18.1
Radioactivity
A. Radioactive Decay
Decay series and
Nuclear Particles
Video
Section 18.1
Radioactivity
A. Radioactive Decay
• Tell what kind of decay these undertake:
• 11647 Ag 
+ 11648 Cd
• 21183 Bi 
+ 20781 Tl
•
•
•
•

8 O
210
89 Ac
131
53 I 
88
35 Br 
15
+ 157 N
+ 20687 Fr
+ 13154 Xe
+ 8835 Br
Section 18.1
Radioactivity
A. Radioactive Decay
• Write the decay equation for:
• 22688 Ra by alpha
•
214
•
•
•
11
6
195
82
Pb by beta
C by positron
79
Au by e- capture
Section 18.1
Radioactivity
B. Nuclear Transformations
• Nuclear transformation – change of one element to
another
• Bombard elements with particles (reverse of decay…)
Section 18.1
Radioactivity
B. Nuclear Transformations
• Transuranium elements – elements with atomic numbers
greater than 92 which have been synthesized
Section 18.1
Radioactivity
C. Detection of Radioactivity and the Concept of Halflife
• Geiger-Muller counter – instrument which measures
radioactive decay by registering the ions and electrons
produced as a radioactive particle passes through a gasfilled chamber VIDEO
Section 18.1
Radioactivity
C. Detection of Radioactivity and the Concept of Halflife
• Half-life – time
required for half of
the original sample of
radioactive nuclides
to decay VIDEOS
• Will the original
quantity ever be
depleted?
Section 18.1
Radioactivity
C. The Concept of Half- Life
• Given the half life of Pa-234 is 1.2 minutes, what
fraction of the original sample will remain after
7.2 minutes?
• 6 half-lives
• 1.56%
• How many half lives need to pass until the
original amount is essentially depleted?
• 12? 14? 16?
• How much time would it take to pass 16 ½ lives?
Section 18.1
Radioactivity
C. The Concept of Half- Life
• Given the half life of U-238 is 4.5 X 109 years
(4.5 billion), what how long until the original
amount is essentially depleted?
Section 18.1
Radioactivity
C. The Concept of Half- Life
• If the half life of Ra-223 is 12 days, how long will
it take for a sample containing 1.0 mol of Ra-223
to reach a point where it only contains 0.25 mol
of Ra-223?
Section 18.1
Radioactivity
C. The Concept of Half- Life
• “Glow in the dark” time pieces used to made with
Ra-228 paint. Assuming that 8.0 X 10-7 mol of Ra228 was originally used to paint the number 3
and that many years later only 1.0 X 10-7 mol of
Ra-228 remained on the 3, approximate the age
of the watch.
• ½ life Ra-228 = 6.7 years
Section 18.1
Radioactivity
C. Detection of Radioactivity and the Concept of Halflife
• Achilles and the tortoise
• “In a race, the quickest runner can never
overtake the slowest, since the pursuer must first
reach the point whence the pursued started, so
that the slower must always hold a lead.”—
Aristotle, Physics VI:9, 239b15
• Give a tortoise a head start……
• The answer is obvious if you consider infinite
converging theories…
Section 18.1
Radioactivity
Objectives Review
1. To learn the types of radioactive decay
2. To learn to write nuclear equations for
radioactive decay
3. To learn how one element may be changed to
another by particle bombardment
4. To learn about radiation detection instruments
5. To understand half-life
6. Work Session: Page 869 # 11, 13, 18, 19, (B
particle is e-), 27 (more or less)
Section 18.2
Application of Radioactivity
Objectives
1. To learn how objects can be dated by
radioactivity
2. To understand the use of radiotracers in
medicine
Section 18.2
Application of Radioactivity
A. Dating by Radioactivity
Radiocarbon dating – not a precursor to
chemistry.com
• Originated in 1940s by Willard Libby
– Based on the radioactivity of carbon-14
• Used to date wood and artifacts
• What kind of decay is this?
Section 18.2
Application of Radioactivity
A. Dating by Radioactivity
• Radiocarbon dating C-14 is formed in the
atmosphere by invading neutrons from space
• 147 N + 10 n  146 C + 11 H
• Over time, an equilibrium has resulted between the
formation and decay of C-14 resulting in a constant
concentration on the atmosphere.
• As plants photosynthesize, their C-14 content is the
same as in the atmosphere.
• When a plant stops photosynthesizing, the C-14
begins to decay with ½ life = 5730 years.
• A wooden bowl with ½ the concentration of C-14 as
in the atmosphere is approx 5730 years old…
Section 18.2
Application of Radioactivity
B. Medical Applications of Radioactivity
Radiotracers
• Radioactive nuclides
that can be introduced
into organisms and
traced for diagnostic
purposes.
• PHeT Dating
• Old Dress
Section 18.2
Application of Radioactivity
Section 18.2
Application of Radioactivity
Section 18.2
Application of Radioactivity
550 – 750 AD Basketmakers
750-1100 AD Developmental Pueblo
1100 – 1300 AD Great Pueblo Period
Section 18.2
Application of Radioactivity
Objectives Review
1. To learn how objects can be dated by
radioactivity
2. To understand the use of radiotracers in
medicine
3. Work Session: Attached to the last work
session
Section 18.3
Using the Nucleus as a Source of Energy
Objectives
1. To introduce fission and fusion as sources
of energy
2. To learn about nuclear fission and how a
nuclear reactor works
3. To learn about nuclear fusion
4. To see how radiation damages human
tissue
5. To use Einstein’s energy equation E = mc2
Section 18.3
Using the Nucleus as a Source of Energy
A. Nuclear Energy
• Two types of nuclear processes can
produce energy
– Splitting a heavy nucleus into 2 nuclei
with smaller mass numbers - fission
(take apart) (Nuclear Power Plants)
– Combining 2 light nuclei to form a heavier
nucleus - fusion (put together) (Sun’s Rx)
Section 18.3
Using the Nucleus as a Source of Energy
B. Nuclear Fission
• Releases 2.1 1013 J/mol uranium-235
• Each fission produces 3 neutrons
Section 18.3
Using the Nucleus as a Source of Energy
B. Nuclear Fission
• Chain reaction –
self sustaining
fission process
caused by the
production of
neutrons that
proceed to split
other nuclei
• Critical mass –
mass of
fissionable
material required
to produce a chain
reaction
Section 18.3
Using the Nucleus as a Source of Energy
B. Nuclear Bomb?
Section 18.3
Using the Nucleus as a Source of Energy
B. Nuclear Fission
Section 18.3
Using the Nucleus as a Source of Energy
C. Nuclear
Reactors
Section 18.3
Using the Nucleus as a Source of Energy
C. Nuclear Reactors
Reactor core control
PHeT Fission
Section 18.3
Using the Nucleus as a Source of Energy
C. Nuclear Reactors Potential Hazards?
• Three Mile Island
Middleton, Pa 4-1-79
• Partial meltdown
• Chernobyl Ukraine,
Russia, 4-27-86
• Complete meltdown
• Approx 600,000 highly
exposed people
• Covered by concrete
sarcophagus
• Still Radioactive….
Section 18.3
Using the Nucleus as a Source of Energy
• Fukushima, Japan 1, 2
• March 11, 2011 Triple
Meltdown after
Tsunami
• August 2013
radioactive radiation
still leaking into the
ocean
• June 2013 Cs-134
Vancouver , BC concs
0.9 Bequerels/m3
• Safe Drinking Water
standard 28 Beq/m3
Section 18.3
Using the Nucleus as a Source of Energy
ICBM Missile
Section 18.3
Using the Nucleus as a Source of Energy
C. Nuclear Reactors and Nuclear Waste
• In the United States today, over 161 million people
reside within 75 miles of temporarily stored nuclear
waste.
• This opinion is reflected in a 1990 report from the National
Research Council of the National Academy of Sciences, which
states that there is “a worldwide scientific consensus that deep
geological disposal, the approach being followed by the United
States, is the best option for disposing of highly radioactive
waste.”
• http://www.ocrwm.doe.gov/factsheets/doeymp0338.shtml
• Earthquake?
Section 18.3
Using the Nucleus as a Source of Energy
D. Nuclear Fusion
• Process of combining 2 light nuclei
• Produces more energy per mole than fission
• Powers the stars and sun
Section 18.3
Using the Nucleus as a Source of Energy
D. Nuclear Fusion
• Requires extremely high temperatures
• Currently not technically possible for us to
use as an energy source
• 2 million Kelvins!!
• Cold Fusion claim…late 1980’s
• http://www.physorg.com/news131101595.html
• http://en.wikipedia.org/wiki/Cold_fusion
Section 18.3
Using the Nucleus as a Source of Energy
D. Energy Calculations
• Einstein’s energy equation E = mc2
• E = energy released (J)
• m = mass difference between reactants and
products (kg)
• C = speed of light 3.0 X 10 8 m/s
• Law of conservation of mass?
• Beam me up, Scotty…
Section 18.3
Using the Nucleus as a Source of Energy
D. Energy Calculations
• Einstein’s energy equation E = mc2
• How much energy will be released when 1
mole of Ra-226 decays by alpha emission
to produce Rn-222. [J = kg(m2/s2)]
• 22688 Ra  22286 Rn + 42He
• 1 mole  1 mole + 1 mole
• 226.0254 g  222.0175g + 4.0026g
• 0.0053g difference- where’d it go?
• E = mc2
Section 18.3
Using the Nucleus as a Source of Energy
D. Energy Calculations
•
•
•
•
•
•
•
•
Einstein’s energy equation E = mc2
0.0053g difference- where’d it go?
E = mc2
E=?
m = 0.0053g
=
kg
C = 3 X 108 m/s
E = mc2 = (5.3 X 10-6kg)(3 X 108 m/s)2
E = 4.8 X 1011 J
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
Factors Determining Biological Effects of Radiation
• Energy of the radiation
• Penetrating ability of the
radiation
• Ionizing ability of the radiation
• Chemical properties of the radiation source
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
•
•
•
•
•
•
•
•
•
Alpha- stopped by skin
Beta- cm depth
Gamma- highly penetrating
Ionization?
Alpha- highly
Gamma-occasional ionization
Kr-85 and Sr-90 both Beta source
Kr-noble, pass through system
Sr- similar to Ca- leukemia, bone
cancer
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
Section 18.3
Using the Nucleus as a Source of Energy
E. Effects of Radiation
•
•
•
•
•
•
Government Recommendation: < 500 mrems/yr
X ray- dental…20 mrems
X ray- chest…50 mrems
Smoking…
10,000 mrems/yr
Idaho Daily EPA RadNet Monitoring
Section 18.3
Using the Nucleus as a Source of Energy
Objectives Review
1. To introduce fission and fusion as sources
of energy
2. To learn about nuclear fission and how a
nuclear reactor works
3. To learn about nuclear fusion
4. To see how radiation damages human
tissue
5. To use Einstein’s energy equation E = mc2
6. Work Session: Review Page 870 # 35
Section 18.1
Radioactivity
C. Detection of Radioactivity and the Concept of Halflife
• Scintillation counter – instrument which measures the
rate of radioactive decay by sensing flashes of light that
the radiation produces in the detector