Name: _______________________________________________________ Score: ___________
Blizzard Bag 1: The Manhattan Project
Recall, neutrons weren’t discovered until 1932. Up until this point, scientists didn’t
understand how elements could undergo radioactivity, but still have the same number of
protons AND change their masses afterwards.
1. What do neutrons accomplish in the nucleus? What happens if we change the number
of neutrons that are present in the nucleus?__________________________________
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Once neutrons were discovered by Chadwick, it was noticed that elements try to maintain a
rough one-to-one ratio of neutrons to protons. If an atom has too many neutrons it splits itself
to release the excess neutrons, and energy in the process. If atoms are nearby, they may
absorb these emitted neutrons. If they do, they will become unstable as well and spit out even
more neutrons. This creates a nuclear fission chain reaction of splitting atoms – the atoms
will keep absorbing and releasing these neutrons until they become stable.
2. The fission chain reaction was noted in 1936 by European scientists, particularly by
Leo Szilard. In 1932, scientists in Berlin managed to split an atom of uranium.
Numerous scientific papers were being published about nuclear fission with Uranium,
but the papers ceased to be published around 1942. Think about what was happening
historically around 1942. What was going on in Europe, and why would scientists in
Germany want to stop publishing papers about nuclear fission?
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Theodore Roosevelt received this letter from Albert Einstein in 1939 (see next page).
Albert Einstein
Old Grove Rd.
Nassau Point
Peconic, Long Island
August 2nd 1939
F.D. Roosevelt
President of the United States
White House
Washington, D.C.
Sir:
Some recent work by E.Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem
to call for watchfulness and, if necessary, quick action on the part
of the Administration. I believe therefore that it is my duty to bring
to your attention the following facts and recommendations:
In the course of the last four months it has been made probable through the work of Joliot in France as well as Fermi and Szilard in
America - that it may become possible to set up a nuclear chain reaction
in a large mass of uranium,by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears
almost certain that this could be achieved in the immediate future.
This new phenomenon would also lead to the construction of bombs,
and it is conceivable - though much less certain - that extremely power-
ful bombs of a new type may thus be constructed. A single bomb of this
type, carried by boat and exploded in a port, might very well destroy
the whole port together with some of the surrounding territory. However,
such bombs might very well prove to be too heavy for transportation by
air.
-2The United States has only very poor ores of uranium in moderate
quantities. There is some good ore in Canada and the former Czechoslovakia.
while the most important source of uranium is Belgian Congo.
In view of the situation you may think it desirable to have more
permanent contact maintained between the Administration and the group
of physicists
working on chain reactions in America. On e possible way
of achieving this might be for you to entrust with this task a person
who has your confidence and who could perhaps serve in an inofficial
capacity. His task might comprise the following:
a) to approach Government Departments, keep them informed of the
further development, and put forward recommendations for Government action,
giving particular attention to the problem of securing a supply of uranium ore for the United States;
b) to speed up the experimental work,which is at present being carried on within the limits of the budgets of University laboratories, by
providing funds, if such funds be required, through his contacts with y
private persons who are willing to m ake contributions for this cause,
and perhaps also by obtaining the co -operation of industrial laboratories
which have the necessary equipment.
I understand that Germany has actually stopped the sale of uranium
from the Czechoslovakian mines which she has taken over. That she should
have taken such early action might perhaps be understood on the ground
that the son of the German Under-Secretary of State, von Weizsäcker, is
attached to the Kaiser-Wilhelm-Institut in Berlin where some of the
American work on uranium is now being repeated.
Yours very truly,
(Albert Einstein)
Up until this letter, scientists in the U.S. had done very little research on atomic fission. This
letter spawned the Manhattan Project. Because the U.S. had done very little research
regarding atomic bombs up to this point, they recruited top scientists from all over the world
to aid in this endeavor.
The sole purpose of the Manhattan Project was to develop the first atomic bomb, and
hopefully use it to end WWII. The Project proceeded slowly at first because the scientists
were faced with a conundrum: They knew that they had to use uranium, because it is the
heaviest naturally occurring element. Therefore, it has the potential to create the most energy
if it is split and decays into plutonium. Uranium—235 is incredibly expensive and difficult to
purify. If they didn’t use enough uranium, there wouldn’t be enough energy for the chain
reaction and the bomb would fizzle out. If they used too much, the bomb would work but
purifying excess uranium would take a lot more time, which wasn’t readily available. They
were in the midst of the war and didn’t want to prolong it.
The scientists on the Manhattan Project realized calculating the exact amount of uranium
needed was very complicated. So instead, they took a sample of uranium and ran random
trials on it for years. They analyzed how neutrons collided with the uranium and plutonium at
different speeds, angles, etc. and they recorded all of the data. They had to hire in a lot of
outside help simply to help with the calculations, and to compute the data (hence the name,
computers). In July 1945, the Manhattan Project perfected the chain reaction and tested the
bomb out in the desert in Arizona. It worked, and 3 weeks later on August 9, 194, atomic
bombs were dropped on Hiroshima and Nagasaki Japan.
3. What role did Albert Einstein play in the Manhattan Project? Did he work directly on
the atomic bomb? _____________________________________________________
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4. Why did The Manhattan Project use Uranium, of all elements?
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5. Uranium—238 is bombarded with a neutron, becoming Uranium—239. It then
undergoes 2 beta decay reactions, to eventually become Plutonium—239. Show this
reaction with the proper nuclear equations:
A)
239
92
𝑈
0
−1
𝑒 +
B)
6. When Einstein learned that the U.S. dropped the atomic bombs on Japan, he said
“Woe is me.” He claimed that he would have never prompted the US to work on their
atomic bomb had he known that Germany would not succeed in making an atomic
bomb. Do you agree with Einstein, or do you think dropping the atomic bomb was
justifiable? Explain your answer. __________________________________________
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When atomic bombs detonate, they kill with heat rather than radiation. Of course there is
going to be some lingering radiation with all atomic bombs, but the majority of the deaths are
from the heat flash. Surprisingly, there are elements far more dangerous than Uranium. If a
“dirty atomic bomb” were to be created, the resultant radiation would be 100 times worse.
One of the scientists that worked on the Manhattan Project, Leo Szilard, calculated that
sprinkling just a tenth of an ounce of cobalt – 60 on every square mile of earth would pollute
the earth with enough gamma rays to wipe out the human race, a nuclear version of the cloud
that helped kill the dinosaurs. He proposed a warfare device that consisted of a multistage
warhead surrounded by a jacket of cobalt—59. Lots of elements emit gamma rays, but
there’s something special about cobalt. Hiroshima and Nagasaki were more or less habitable
within days of their explosions. If cobalt were to be used in an atomic bomb, cobalt atoms
would settle into the ground like tiny land mines. Enough radiation would go off right away
to make it necessary to flee, but the cobalt atoms will still be emitting the same amount of
gamma radiation for our entire lifetimes. These emitted gamma rays will “dig down into the
bone marrow and scramble the chromosomes in the white blood cells. The cells either die
outright, grow cancerous, or grow without constraint and, like humans with gigantism, end
up deformed and unable to fight infections (Sam Kean).”
Although cobalt has the potential to cause drastic damage in wars, it’s unlikely to ever be
used because it doesn’t allow the conquering army to occupy and “claim” any territory.
Although Szilard didn’t expect anybody to actually carry out his idea of dirty atomic bombs
involving cobalt, he was wrong. When the idea was incorporated into books such as Dr.
Strangelove, the U.S. and Soviet Union adopted a doctrine called MAD (Mutual Assured
Destruction). This doctrine doesn’t support the idea of using any atomic bombs in wars
because, outcome aside, both sides will lose in a nuclear war.
7. Why is an atomic bomb laced with cobalt—60 more dangerous than a regular atomic
bomb prompted by a fission reaction? ______________________________________
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8. Explain MAD (Mutually Assured Destruction) in your own words: how do both sides
lose in a nuclear war?
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