Nuclear Reactions Activity
Nuclear reactions are those that involve changes inside the
nucleus of an atom. (This is opposed to chemical reactions, which
involve changing the electrons around the nucleus.) There are
basically two types of nuclear reactions: fusion and fission.

Nuclear fusion is the joining together of two or more nuclei
to form a single, larger nucleus.

Nuclear fission is the splitting of a nucleus into a smaller
nucleus and one or more nuclear particles.
Nuclear reactions are often regarded as elusive and exotic,
but they occur as frequently as chemical reactions. The evidence
of nuclear decay is usually subtle and invisible, and these
changes went unnoticed by scientists until the turn of the 20th
century. However, when evidence of nuclear reactions is readily
apparent, it can be spectacular.
Both nuclear fusion and nuclear fission reactions are
accompanied by some type of radioactive decay. Radioactive decay
occurs when an unstable nucleus spontaneously emits high-energy
nuclear particles, becoming more stable. There are three basic
types of radioactive decay: alpha decay, beta decay, and gamma
radiation.

Alpha decay occurs when a nucleus emits a particle of two
protons and two neutrons, called an alpha-particle.
(notated: α or 24He2+)

Beta decay occurs when a nucleus emits an electron or a
positron, called a beta-particle.
(notated: β- = electron,
β+ = positron)
Note: Beta decay is always accompanied by the release
of a neutrino (notated: ν). A neutrino is like an
electron without a charge.

Gamma radiation occurs when a nucleus emits high energy
electromagnetic radiation.
(notated: γ)
Use the atom boards to model the types of nuclear reactions
discussed below.
Part I: Nuclear Fusion
Nuclear fusion is perhaps best known by its ominous
manifestation, the hydrogen bomb. But you are witness to nuclear
fusion almost every day of your life. The sun is powered by an
ongoing (for billions of years) nuclear fusion reaction. The sun
primarily burns hydrogen, fusing it into helium, but heavier
elements are also fused in the sun and in other stars. For that
matter, astronomers believe that all elements in the universe
were created in stars by the process of nuclear fusion!
The sun uses hydrogen atoms to fuse them into helium atoms
in a three-step process called a proton-proton fusion chain. Use
the atom board to model this process:
Record the nuclear equation for each step on numbers 1-3 of
your answer sheet.
1.
2.
3.
Two protons fuse together forming a hydrogen-2 nucleus,
and release a positron and a neutrino.
One proton fuses with the hydrogen-2 nucleus, forming a
helium-3 nucleus, and release a gamma ray
Two helium-3 nuclei fuse to form a helium-4 nucleus,
while releasing two protons
Notice that no electrons are mentioned in the above
description of fusion. This is because a nuclear fusion reaction
is very exothermic, and takes place at such high temperatures
that matter is in the plasma state. Electrons are dissociated
from nuclei in the plasma state.
Part II: Nuclear Fission and Half-Life
Like nuclear fusion, nuclear fission is accompanied by the
release of thermal energy. Unlike nuclear fusion, which is a rare
event on Earth, nuclear fission is commonplace. The scorching hot
temperatures of the deep Earth are due in part to countless
fission reactions. All around the globe (even in the permafrost
of the arctic circle) if you dig deep enough, you’ll find that
the Earth’s crust can reach temperatures of 400°C!
In nature, nuclear fission is a spontaneous process that
occurs when unstable isotopes decay into more stable forms.
Different isotopes decay at widely different rates. The more
unstable the isotope, the more quickly it decays. The more stable
the isotope, the more slowly it decays. The measure of how
quickly an isotope decays is called its half-life.

Half-life is defined as the time it takes for half of a
sample of a substance to decay into a more stable form.
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For example, cobalt-60 decays into nickel-60 and has a halflife of 5 years. If you had a 6-gram sample of cobalt-60, in 5
years you would have 3 grams of cobalt-60 and 3 grams of
nickel-60. In ten years you have 1.5 grams of cobalt-60 and
4.5 grams of nickel-60. In fifteen years you would have 0.75
grams of cobalt-60 and 5.25 grams of nickel-60. And so on…
Radioactive Decay of Cobalt-60
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Mass (grams)
5
4
3
cobalt-60
nickel-60
2
1
0
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95 100
Time (years)
Hale life can be calculated by the following formula:
Ct = Co•(1/2)t/t1/2
Where Ct = amount of radioactive substance that still
remains
Co = the original amount of radioactive
substance
t = is time elapsed
t1/2 = half-life of the decaying substance
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Record your responses to the following problems on numbers
4-8 on your answer sheet.
4. Beryllium-10 decays into boron-10 with a half-life of
2,700,000 years.
a. Create a beryllium-10 atom on your atom board. Record the
isotopic notation of beryllium-10.
b. Now create a boron-10 atom on your atom board. Record the
isotopic notation of boron-10.
c. What type of radioactive decay occurred to produce boron10 from beryllium-10?
d. Record the nuclear equation for this transformation.
5. Calcium-41 decays into potassium-41 with a half-life of
100,000 years.
a. Create a calcium-41 atom on your atom board. Record the
isotopic notation of calcium-41.
b. Now create a potassium-41 atom on your atom board.Record
the isotopic notation of potassium-41.
c. What type of radioactive decay occurred to produce
potassium-41 from calcium-41?
d. Record the nuclear equation for this transformation.
6. Iron-59 decays into cobalt-59 with a half-life of 45 days.
a. Create an iron-59 atom on your atom board. Record the
isotopic notation of iron-59.
b. Now create a cobalt-59 atom on your atom board. Record
the isotopic notation of cobalt-59.
c. What type of radioactive decay occurred to produce
cobalt-59 from iron-59?
d. Record the nuclear equation for this transformation.
7. Uranium-238 decays into thorium-234 with a half-life of
4.51 x 109 years.
a. Since the atom board is not big enough to model this
atom, simply record the isotopic notation of uranium-238.
b. Record the isotopic notation of thorium-234.
c. What type of radioactive decay occurred to produce
thorium-234 from uranium-238?
d. Record the nuclear equation for this transformation.
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