Chapter 25
Nuclear Chemistry
Chemical vs. Nuclear Reactions
Chemical
Reactions- A rearrangement of atoms and
molecules by breaking and
forming bonds
-involves electrons
Nuclear
Reactions- Combining, splitting or decay
the nuclei of atoms.
Nuclear Chemistry involves
the NUCLEUS of the atom.
That means…. the protons and
neutrons will undergo a change (nuclear
reactions)
Nuclear reactions usually involve
radioactive elements
Radioactive Elements are
NOT stable….
…because of the proton to neutron ratio.
Radioactivity & Radiation Alpha, Beta, Gamma - YouTube
Radioactive elements will give off
particles and energy until they
become stable (non-radioactive)
Radioactive elements
change by themselves
Of the 119+ different atoms….
…there are more than 1500
different nuclei, only 264 are stable
Discovery of Radioactivity
Professor Roentgen – 1895found that certain
elements gave off X-rays
but didn’t know what
caused them.
Antoine Henri Bacquerel
•1896
•exposed a uranium-bearing
crystal to sunlight
•then placed it on a
photographic plate
the crystal produced an
image
Bacquerel theorized…
…..that the absorbed energy of the
sun was being released by the
uranium in the form of x-rays
This theory was proven incorrect
because when he didn’t expose it to light,
he still got the image
Since the crystal produced its
own image on the plate without
being expose to sunlight, he
theorized that the crystal
produced its own rays.
HowStuffWorks Videos "100
Greatest Discoveries:
Radioactivity"
Marie and Pierre Curie
-Marie Curie (1867-1943) and Pierre Curie
(1859-1906)
-They found that
uranium gave off
particles from the
nucleus- (shown by a
change in mass)
-Won Nobel Prize in 1903
for this research
Next they……
• Studied pure uranium vs. ore containing
uranium
• ore was more radioactive than the pure
material.
• Conclusion: ore contained additional
radioactive components besides the
uranium.
• This observation led to the discovery of
two new radioactive elements, polonium
and radium.
-Marie won 2nd Nobel Prize in
1911 for finding the radioactive
elements polonium and radium.
•1910 In honor of Marie and
Pierre Curie……the Radiology
Congress chose the curie as
the basic unit of radioactivity
-Marie organized first mobile x-ray
machines to be used in World War I
-Marie pioneered use of
radiation in cancer treatment
-Marie died of leukemia in 1943.
Ernest Rutherford
(1871-1937)
• father of nuclear physics.
• Particles named and characterized by him
include the alpha particle, beta particle and
proton.
Nuclear Science
•
•
•
•
Began with Albert Einstein
E = mc2
Energy= mass x (speed of light)2
Speed of light - 299,792,458 m/s
(meters per second) or
186,000miles/second or 671 million
miles/hr. (around earth in 1.3 seconds)
• very small amounts of mass may be
converted into a very large amount
of energy
The Case of the
Doomed Dial
Painters
• In 1917, pretty Florence Kohler Casler was happily
engaged in her first job. At the U.S. Radium
Corporation’s plant in Orange, NJ, she sat by a
table covered with watch dials. Tipping a tiny
brush continuously with her tongue, she coated
their numerals with luminous paint containing tiny
amounts of radium. Two years later she quit and
got married. In 1949, cancer developed in her
sinuses. Last week, Florence Casler died, the 41st
victim of the famous radium poisoning of the
1920’s.
•
LIFE Magazine, December, 1951.
Radium watch dial painters
• In 1917, many young women working
for the United States Radium
Corporation thought they had found
the perfect job. Wages were good
and the work was easy. As watch
dial painters, all they had to do
was mix up a batch of glow-in–thedark radium based paint and brush
the paint on the watch dials. In
order to apply the paint precisely,
they were encouraged to “sharpen”
the points of the brushes with their
tongues.
At the time, radiumbased glow-in-the-dark
paint was a popular
gimmick. People loved
watches they could read
in the dark. Some of the
workers even painted
their nails with it or
sprinkled it in their hair.
No one ever told them it
was deadly.
In the early 1920s,
however the dial painters
started getting sick. The
women began losing their
teeth and suffering from
gum ulcers, anemia, tumors
and “jaw rot” – a painful
decay of bone and tissue in
the mouth. By 1924, 50
women were ill and a dozen
had died.
Doctors and dentists were mystified.
An increasing number of seemingly
healthy young women were developing
terrible symptoms and the only thing the
women had in common was the fact that
they had all worked at the same job for
the United States Radium Corporation.
NOT US !
Authorities at the New Jersey
Department of Labor failed to identify
anything hazardous at the work site. The
United States Radium Corporation
accepted no responsibility, claiming that
the women’s ills were due to “poor dental
habits” or in the words of the company’s
president, “a hysterical condition
brought about by coincidence”. But some
people suspected that radium was the
cause.1
THE PLOT THICKENS
In 1925, Dr. Harrison S.
Martland, the Medical Examiner
of Essex County, was asked to
investigate the death of a 36 year
old man, who was employed as a
chemist by the United States
Radium Corporation. The man,
who had been diagnosed with
anemia, presented Dr. Martland
with a puzzling situation. For a
case of normal anemia, death had
come much too quickly.2
Dr. Martland was intrigued. He
consulted with an expert on radiation,
Dr. Sabin A. Von Sochocky, a founder of
the United States Radium Corporation
and the inventor of the radium paint the
workers had been using. Together, they
analyzed tissue and bone from the
chemist who had died. The results were
startling. The chemist’s body was
saturated with radioactivity! Dr.
Martland and Dr. Von Sochocky
suspected that others who had worked at
the factory were contaminated, too.3
SOLVING THE MYSTERY
Dr. Martland and his team built a
radiation detector (somewhat like a
Geiger counter) and tested one of the
dying dial painters. When she breathed
into their detector, they saw that she was
filled with radioactivity.
After the dial painter died,
Dr.Martland removed a splinter of bone
from her body. When he strapped a
paper clip, a broken blade and dental xray film to the dead woman’s leg, her
bone had absorbed so much radium that
it emitted enough radiation to expose the
film and silhouette the bits of metal.
Dr. Martland tested other painters.
Whether they appeared healthy or sick,
they were all radioactive. Von Sochocky
tested himself and discovered that his
breath contained higher levels of
radioactivity than anyone else tested. He
subsequently died “a horrible death”.4
(Aplastic anemia)
On December 5, 1925, Dr. Martland
presented his finding in The Journal of the
American Medical Association. For the first
time, the deadly effects of radiation had been
clearly established.5
•
•
•
•
•
Marc Mappen.”Jerseyana”. The New York
Times, March 10, 1991, Sunday Late edition,
Section12NJ,p.13
2 Ibid
3Ibid
4Ibid
5Ibid
1
Substances that give off
particles from the nucleus are
radioactive.
• Radioactivity -the process in which
an unstable atom emits charged
particles and energy to become a
stable atom
• proton to neutron ratio determines
what type of radiation is given off
Only certain isotopes
(nuclides) are radioactive
• Nuclide- a specific nucleus
• Nuclides that are radioactive are
called radioisotopes
Radioisotopes (unstable
atoms)
-atoms
with more than 83
protons are usually
unstable
Transuranium
Elements
• The elements past
uranium (#92)
• All radioactive
Showing Radioactive Atoms.
Use Isotope Notation
C-12
C-14
Mass number
12
6
14
C
6
Atomic number
C
To become stable,
radioisotopes give off
radiation (Radioactive decay)
radiation
Unstable
atom
Types of Radiation
•Alpha Particle: α
•Beta Particle: β
•Gamma Ray: γ
Alpha Decay
-when an atom gives off an alpha particle
Alpha Particle = 2p and 2n
-atomic # goes down 2 and
atomic mass goes down 4
Alpha Decay
-Written as:
4
2
He
(in nuclear equations)
or
a (in decay series)
-U-238 turns into Th-234 when it
gives off an alpha particle
Ex.
(nuclear equation)
238
U
92
4
234
Th
He
+
90
2
Alpha Particles
-weakest radiation
-can be stopped by a piece of paper.
-can burn flesh
Affects of Alpha Particles
on Body
• will not penetrate the outer layer of
skin
• dangerous if inhaled or swallowed.
• Cells in lining of the lungs or internal
organs will be changed (mutated) or
killed
• lung cancer cases among uranium
miners from inhaled and ingested
alpha sources is much higher than
those of the public at large.
Radon
•Radon gas
•produced by the decay of radium-226
• emits alpha particles
• poses a hazard to lungs and airways
when inhaled.
Two types:
Beta Decay
Beta minus decay
Beta plus decay
Written as β+
- Written as b-
or
0e
-1
0e
+1
A. BETA MINUS DECAY:
• Neutron decays into a proton, an
electron and an antineutrino
• Mass number remains the same but
atomic # increases by 1
Beta minus decay
n
228
88 Ra
p + e- + antineutrino-
B. BETA PLUS (positron) DECAY
• A proton decays into a neutron, a
neutrino and a positron
• Mass number remains the same
• Atomic Number decreases by 1
Beta plus decay
p
230
91 Pa
n + positron+ + neutrino
-neutron breaks apart
-proton breaks apart
Beta Particles
-100x more penetrating
than an alpha particle
-can be stopped by clothing
or wood
-travel at the speed of light
-usually accompanies other
modes of radioactive decay
Which type of beta is given off?
(it depends on the proton to neutron ratio)
Too many neutrons = beta minus decay
p + e- + antineutrino-
n
Ex.
14
6
C
Too few neutrons – Beta plus decay
Proton
neutron + neutrino and positron
-Positron has the mass of an
electron but is positively charged
10
6
C
Gamma Decay
-gives off a gamma ray (
γ)
- a release of high energy
electromagnetic radiation from nucleus
-it’s pure energy not a particle
-Atomic # and mass stay the same, just
changes to an atom with less energy
- needs thick walls of concrete or lead
to stop it.
Nuclear equations
• Show one transformation of a decay series
• Must be equal on both sides. !!!!!!!!!
Alpha decay equation
237
Np
93
Beta minus decay equation
32 P
15
Beta plus decay equation (positron decay)
15
O
8
Other Particles Released from
Nucleus and /or absorbed
particles
•Add or subtract the atomic mass and
adjust the atomic number.
Write the equation showing the release
of a neutron from a U- 238 nucleus.
Absorbed Particles
Ex. Write the nuclear equation for when
U-238 is bombarded with and absorbs an
alpha particle
Decay Series
- shows the progression of changes a
radioactive element goes through
-uses symbols:
α = alpha particle
β = beta particle
γ = gamma radiation.
Penetrating Power
Alpha, Beta and Gamma
Radiation
Half- Life
- the time it takes for half of the
sample of a radioactive element to
decay.
-half-lives are different for each
element.
-ex. Rh-106 half-life = 30 seconds
U-238 half-life = 4.5 billion years
Half Lives
•
•
•
•
•
•
Radioisotope
Half-life
Radon-222
Strontium-90
Radium-226
Plutonium-239
Uranium-235
4 days
28 years
1602 years
24 400 years
700 000 000 years
Half-life of a Radioactive
Element?
What is the half-life of
Cesium-137?
What is the half-life of Sodium-24?
How many half-lives does Na-24
undergo in 45 hours?
Half-Life Problem
Cs-129 has a half-life of 32.0 hours.
If you start with 130grams of Cs-129,
how many grams will be remaining
after 12 days?
First determine # of half-lives it will
go through
Then divide the amount in half(2) to the
power of half-lives
Transmutation
-when an element changes into a
different element. (* hint: Proton # must
change)
3 ways it can occur:
natural
1. Radioactive decay
Artificial
2. Bombard nucleus with a
particles or neutrons
3. Expose to extremely high
temp. causing nuclei to fuse
Transmutations
give off
radiation !!!!
Natural Background Radiationwhere does it come from?
• Cosmic radiation – comes from the sun
Terrestrial radiation – comes from
radioactive elements found in earth’s
crust.
Where do we get the most
radiation exposure?
Need another reason why not to smoke?
In addition to all the other chemicals in cigarettes,
the tobacco leaves used in making cigarettes
contain radioactive material, particularly lead-210
and polonium-210.
Effects of Radiation
1. Damages or kills cells and tissues
2. Alters DNA
3. Reddening of skin
4. Drop in white blood cell count
5. Nausea, fatigue, hair loss
6. Weakens metals
Instruments for Detecting
Radiation
1. Geiger Counter
The Geiger Counter - YouTube
2. Cloud chamber
Cloud Chamber
• The thickness and length of the
cloud trail is different for alpha and
beta particles, so they are able to
distinguish between them
3. Bubble chamber- they show actual trails of
bubbles that are formed as charged particles
force their way through an unstable liquid.
Uses of Radioactive materials
1. Production of electricity
2. Warheads and Atomic Bombs, and
nuclear submarines
States with Nuclear Warheads
(shown in red)
3. Radioactive dating – used to date
artifacts
4. Tracers –a chemical compound in which
one or more atoms have been replaced
by a radioisotope
-
Used in industries and medicine
-
- Radioisotopes of hydrogen, carbon, phosphorus,
sulfur, and iodine have been used extensively to trace
the path of biochemical reactions.
-
used to track the distribution of a substance within a
natural system such as a cell or tissue.
Radioactive tracers are also used to
determine the location of fractures
created by hydraulic fracturing in
natural gas production.
5. Radiation treatments are used to kill
abnormal cells
6. Food irradiation
Radura
7. Mail irradiation – post 9/11- Anthrax
scare
The Beginnings of the
Nuclear Age 1934-1938
• After discovery of neutron,
scientists began to “Play”
• Bombarded nuclei of Uranium
atoms with neutrons
• Caused uranium nucleus to split
Two Kinds of Nuclear Reactions
1. FissionSplitting the nucleus
2. Fusion-
Combining nuclei
During a nuclear reaction small
amounts of mass are changed into
large amounts of energy
E =
2
mc
Nuclear Fission
-Splits nucleus of atom
- releases a tremendous amt. of energy
-used in reactors and atomic bombs
-Dangerous because of radioactive
wastes and possible leaks
Nuclear Fission: How it causes
the atom to split
• low speed neutron is captured by a
uranium-235 atom
• Atom becomes unstable and splits into
various products
• energy and high speed neutrons are
released
Neutron Moderation
• Normally, neutrons move too fast to
be captured by the nucleus
• Slows down neutrons so reactor fuel
can capture them and use them.
Chain Reaction
Chain Reaction - YouTube
1st Proven Nuclear Fission
Experiment
by Otto Hahn in 1939
-Enrico Fermi –1942produced 1st nuclear chain
reaction
-July 16, 1945 – 1st
atomic bomb tested
in New Mexico
1951-1st 4 electric bulbs lit by
electricity produced by experimental
breeder reactor in Idaho Falls
1953-1st two nuclear submarines
Nautilus and Seawolf
Nuclear submarines
1954-1st Nuclear Power plant in Soviet
Union
-1956 –1st commercial nuclear
power plant opened in England
-1956 – 1st commercial power plant
in U.S. (Shippenport, PA)
Nuclear Power Plant
Cooling tower
reactor
Nuclear Power Plants
- U.S. power plants provide about 20% of
our power.
-fission reactions (split atoms)
-monitored by the NRC Nuclear
Regulatory Commission
How a Nuclear Power Plant
Produces Electricity
TVA: Sequoyah Nuclear Plant
Controlling a reactor
• Control rods in reactor absorb some
of the slow moving neutrons so they
can’t become part of the reaction.
• Prevents the reaction from going too
fast
• In Chernobyl accident, too many
control rods were removed and the
reaction went critical
Cooling Tower
Nuclear Power Plant
Control Room
Nuclear Waste
• Used fuel rods contain some
remaining fuel and products that are
radioactive
Used rods are stored in pools of
boric acid to cool them down and act
as shield to reduce radiation levels.
Neutron
absorbing
material is also
placed between
the rods to
prevent them
from reacting
Dry Cask Storage Containers are
used to help overcrowded
temporary storage pools
Yucca Mountain, Nevadaplanned off-site storage
facility to be built by
government.
-has dry ,
relatively stable
ground
Scheduled to
be completed
by 2010
The Massive TBM (Tunnel Building
Machine) Used to Dig the Tunnels Into
Yucca Mountain
Eureka County, Nevada -- Yucca
Mountain.org -- What's New
Yucca Mtn. Debate
• President Obama – closed Yucca Mtn.
• In contrast to GOP leaders in Congress, Jon
Huntsman, Tim Pawlenty, Gary Johnson and Ron
Paul have all come out in opposition to storing the
nation’s nuclear waste at Yucca Mountain. Other
Republican candidates, including Newt Gingrich,
Rick Santorum and Michele Bachmann, have
ripped the Obama administration’s effort to close
Yucca. Mitt Romney, who won the 2008 Nevada
GOP caucus, has not taken a firm stance on the
controversial issue.
NJ
Nuclear
Power
Plants
Salem
&
Hope Creek
Oyster
Creek
Hope Creek Power Plant, NJ
3 Mile Island
Nuclear Power Plant
Harrisburg, PA
Indian Point Power Plant
Buchanan, NY
Nuclear Power Plants in U.S.
Chernobyl
-1977 – Reactor built in Chernobyl, Russia
http://www.youtube.com/watch?
v=bSRC1_OZPIg
1986 - Worst nuclear reactor
accident in history.
-April 26th – explosion throws tons
of radioactive fuel into atmosphere
-May 4- Soviet government releases
info. about accident.
-May 5th – radiation reaches west
coast of U.S.
-May 7th – ban on food and animals
exported from USSR, Poland, Romania,
Bulgaria, Czech. And Yugoslavia
-May 8th – reactor still burning
-May 25th – experts say it was
human error
-June 24th – concrete slab under
reactor completed
-Nov. 15th – concrete sarcophagus
surrounding reactor completed
-1990 – 10 billion rubles given in
foreign aid to repair
-sarcophagus is leaking earlier than
expected.
-1996 Chernobyl Shelter Fund was
established
-with help from U.S. and many other
nations loans have been secured to
rebuild sarcophagus (2005) and clean
up area
The aftermath of Chernobyl
Chernobyl today. The middle of the picture
shows concrete sarcophagus surrounding
the fatal reactor number four.
http://teachertube.com/viewVide
o.php?video_id=218366&title=C
hildren_of_Chernobyl
Fission vs. Fusion
1. Fission – used today
2. Fusion – promising
for the future
Nuclear Fusion
-the joining of two nuclei to form
one.
-produces a tremendous amt. of
energy
Nuclear Fusion
• light elements combine to form heavier
elements, giving off energy
• takes place in the stars
• core of the sun, temperatures of 10-15
million degrees Celsius
• hydrogen is converted to
helium
-fuel is plentiful and less dangerous.
-waste is safe.
-must be over 1 million oC to start.
-more difficult to control.
Proposed Fusion Reactors
•
•
•
•
isotopes of hydrogen
deuterium H-2 (D)
and tritium H-3 (T)
fuse to form helium and a single
neutron, giving off energy
Fusion of Deuterium and
Tritium
ITER
• Experimental fusion reactor
• A safe, non-polluting nuclear reaction
• 30 year program – 10 year construction, 20
years of operation (beginning in 2016)
• To be built in Cadarache, France
• Hopes to produce 500MWof energy from
50MW by fusing deuterium and tritium
• Will produce 3X more energy than a U-238
fission reaction
• It hopes to be the power resource of the
future
Cold Fusion
*still not proven it can work.
How they say it works.
1. Start with deuterium, send in
pulses of sound wave, then blast the
fluid with neutrons
2. Neutrons create bubbles which
cause the sound waves to rapidly
expand and contract
3. Contractions release enough
energy to fuse atoms
HST Modern Marvels - Inviting
Disaster: Three Mile Island
(2003) - YouTube
HowStuffWorks Videos "Brink:
Evidence of Nuclear Fusion?"
History of Nuclear Power and the
US Navy Submarine (1967) YouTube
TeacherTube Videos - chernobyl