NUCLEAR
CHEMISTRY
STABILITY OF A NUCLEUS
• Nuclei are composed of protons and neutrons.
• Hydrogen is the exception. WHY?!
Nuclear Stability – the larger (more
massive) a nucleus is, the harder it is for it
to stay together.
STABILITY OF A NUCLEUS
• Most nuclei are stable; “Belt of Stability”
– Ratio of n0:p+ in a stable atom varies with size
– Small atoms are stable at a 1:1 ratio
– As atoms become larger, more n0 are needed for stability.
• Ratio of n0:p+ can be driven as high as 1.5:1
• Creates a zone of stability, inside of which the isotopes are
stable.
– Ex.
C-12
C-14
• Outside the zone, nuclei either have too many or too few
neutrons to be stable.
• Unstable nuclei therefore decay
by emitting:
α particles
β particles
γ particles
to bring the ratio back to the
zone of stability.
• All isotopes of all elements
above Bi are unstable and
undergo radioactive decay.
STABILITY OF A NUCLEUS
• When a nucleus is RADIOACTIVE, it gives off decay
particles and changes from one element to another. This is
also known as NATURAL DECAY or NATURAL
TRANSMUTATION.
• Atoms with an atomic number of 1 – 83 have at least one
stable (nonradioactive) isotope, but ALL isotopes of
elements with an atomic number of 84 or more ARE
radioactive.
How do nuclear reactions differ from chemical reactions?
Chemical Rx
Nuclear Rx
• Atoms of elements gain stability by • Nuclei of unstable isotopes gain
losing or gaining estability by releasing decay particles
• Effected by changes in temperature,
that give off large amounts of
pressure, or the presence of a
energy.
catalyst
• NOT effected by changes in
• Requires energy
temperature, pressure, or the
• Can be sped up, slowed down, or
presence of a catalyst.
turned off.
• SPONTANEOUS – does not
require energy.
• Cannot be sped up, slowed down,
or turned off.
Answer Practice Problems #1-2 in Topic 12: Nuclear Chemistry note
packet
STABILITY OF A NUCLEUS
An unstable nucleus releases energy by emitting radiation
during the process of radioactive decay.
Types of Radioactive Decay Particles
Penetrating
Particle
Mass
Charge
Symbol
Power
Alpha
4 amu (made of 2
+2
4
2He
,α
Low
-1
0
−1e
, β-
Moderate
+1
0
+1e
, β+
Moderate
p+ and 2 n0)
Beta
0 amu (made of
an e-)
Positron
0 amu (made of
an anti e-)
Gamma
0 amu
None
γ
High
ALPHA RADIATION
• A.K.A Helium nuclei
• Each alpha particle contains two protons and two neutrons and
has a double positive charge.
• An alpha particle is written 42He or a.
• The electric charge is omitted.
238
92
U
Uranium-238
Radioactive
decay
234
90
Th
Thorium-234
+
4
2
He (a emission)
Alpha particle
ALPHA RADIATION
When an atom loses an alpha particle, the atomic
number of the product is lowered by two and its mass
number is lowered by four.
238
92
U →
234
90
Th +
4
2
He
• In a balanced nuclear equation, the sum of the mass numbers
(superscripts) on the right must equal the sum on the left.
• The same is true for the atomic numbers (subscripts).
Answer Practice Problems #15-16 in Topic 12: Nuclear Chemistry
note packet
-
BETA RADIATION
An electron resulting from the breaking apart of a neutron
in an atom is called a beta particle.
• The neutron breaks apart into a proton, which remains in the
nucleus, and a fast-moving electron, which is released.
1
0
n
Neutron
→
1
1
p
Proton
+
0
–1
e
Electron
(beta particle)
• The –1 represents the charge on the electron.
• The 0 represents the extremely small mass of the electron
compared to the mass of a proton.
BETA RADIATION
Carbon-14 emits a beta particle as it decays and forms nitrogen-14.
14
6
C →
Carbon-14
(radioactive)
14
7
N
+
Nitrogen-14
(stable)
• The nitrogen-14 atom has the
same mass number as
carbon-14, but its atomic
number has increased by 1.
• It contains an additional
proton and one fewer neutron.
0
–1
e (b emission)
Beta particle
BETA RADIATION
A beta particle has less charge than an alpha particle and
much less mass than an alpha particle.
• Thus, beta particles are more penetrating than alpha
particles.
– Beta particles can pass through paper but are
stopped by aluminum foil or thin pieces of wood.
Answer Practice Problems #17-18 in Topic 12: Nuclear Chemistry
note packet
POSITRON
+
A positron is a particle with the mass of an electron but a positive
charge.
• Its symbol is
0
+1e.
• During positron emission, a proton changes to a neutron, just as
in electron capture.
• When a proton is converted to a neutron, the atomic number
decreases by 1 and the number of neutrons increases by 1.
Answer Practice Problems #19-20 in Topic 12: Nuclear Chemistry
note packet
TYPES OF RADIATION
Because of their opposite charges, alpha and beta radiation can
be separated by an electric field.
• Alpha particles move toward the negative plate.
• Beta particles move toward the positive plate.
• Gamma rays are not deflected.
GAMMA RADIATION
A high-energy photon emitted by a radioisotope is called
a gamma ray.
• The high-energy photons are a form of electromagnetic
radiation.
• Nuclei often emit gamma rays along with alpha or beta
particles during radioactive decay.
230
90
Th →
Thorium-230
234
90
Th →
Thorium-234
226
88
Ra +
Radium-226
234
91
Pa +
Protactinium
-234
4
2
He + g
Alpha
particle
0
–1
Gamma
ray
e + g
Beta Gamma
particle
ray
GAMMA RADIATION
Gamma rays have no mass and no electrical charge.
• Emission of gamma radiation does not alter the atomic
number or mass number of an atom.
Gamma rays can be dangerous because of
their penetrating power. What property
determines the relative penetrating power
of electromagnetic radiation?
REMEMBER
High
penetrating
power
Gamma rays can be dangerous because of their penetrating
power. What property determines the relative penetrating
power of electromagnetic radiation?
The wavelength and energy of
electromagnetic radiation determine its
relative penetrating power. Gamma rays
have a shorter wavelength and higher
energy than X-rays or visible light.
Answer Practice Problems #3-14 in Topic 12: Nuclear Chemistry
note packet
NUCLEAR TRANSFORMATIONS
What determines the type of decay a
radioisotope undergoes?
The ratio between neutrons and protons.
The nuclear force is an attractive force that acts between all
nuclear particles that are extremely close together, such as protons
and neutrons in a nucleus.
• At these short distances, the nuclear force dominates over
electromagnetic repulsions and holds the nucleus together.
NUCLEAR STABILITY AND DECAY
Some nuclei are unstable because they have too many
neutrons relative to the number of protons.
• When one of these nuclei decays, a neutron emits a beta
particle (fast-moving electron) from the nucleus.
– A neutron that emits an electron becomes a proton.
– This process is known as beta emission.
– It increases the number of protons while
decreasing the number of neutrons.
NUCLEAR STABILITY AND DECAY
Radioisotopes that undergo beta emission include the following.
NUCLEAR STABILITY AND DECAY
Other nuclei are unstable because they have too few
neutrons relative to the number of protons.
• These nuclei increase their stability by converting a
proton to a neutron.
– An electron is captured by the nucleus during this process,
which is called electron capture.
NUCLEAR STABILITY AND DECAY
Nuclei that have an atomic number greater than 83 are
radioactive.
• These nuclei have both too many neutrons and too
many protons to be stable.
– Therefore, they undergo radioactive decay.
• Most of them emit alpha particles.
– Alpha emission increases the neutron-to-proton
ratio, which tends to increase the stability of the
nucleus.
NUCLEAR STABILITY AND DECAY
In alpha emission, the mass number decreases by four
and the atomic number decreases by two.
NUCLEAR STABILITY AND DECAY
Recall that conservation of mass is an important property
of chemical reactions.
• In contrast, mass is not conserved during
nuclear reactions.
• An extremely small quantity of mass is
converted into energy released during
radioactive decay.
During nuclear decay, if the atomic
number decreases by one but the mass
number is unchanged, the radiation
emitted is
A. a positron.
B. an alpha particle.
C. a beta particle.
D. a proton.
During nuclear decay, if the atomic
number decreases by one but the mass
number is unchanged, the radiation
emitted is
A. a positron.
B. an alpha particle.
C. a beta particle.
D. a proton.
TRANSMUTATION REACTIONS
Transmutation - the conversion of an atom of one element into an atom of
another element.
• 2 forms of transmutation
1. Natural Transmutation – occurs when a single unstable radioactive
nucleus spontaneously changes by decaying (breaking down).
2. Artificial Transmutation – occurs when a stable nonradioactive
nucleus is hit (bombarded) with a high speed particle and is changed to
an unstable nucleus.
** Make a T-Chart identifying the differences between natural
transmutation and artificial transmutation.
ARTIFICIAL TRANSMUTATION
Artificial Transmutation – occurs when a stable nonradioactive nucleus is hit
(bombarded) with a high speed particle and is changed to an unstable nucleus.
• Remember: the ratio of all nuclei with atomic numbers greater than 83 (Bi)
makes those nuclei unstable.
Which of the following always changes when
transmutation occurs?
A. The number of electrons
B. The mass number
C. The atomic number
D. The number of neutrons
Which of the following always changes when
transmutation occurs?
A. The number of electrons
B. The mass number
C. The atomic number
D. The number of neutrons
BALANCING NUCLEAR EQUATIONS
A nuclear equation is balanced when the sum of masses (superscripts) and
sum of charges (subscripts) are equal on both sides of the equation.
SUPERSCRIPT
SUBSCRIPT
222
86Rn
 42He +
218
84Po
A nuclear equation is balanced because:
• The mass numbers (superscripts) on the left (222) is equal to the sum of the
masses on the right (4+218=222)
• The charges (subscripts) on the left (86) is equal to the sum of the charges
on the right (2+84=86)
BALANCING NUCLEAR EQUATIONS
An unbalanced nuclear equation is usually given as an incomplete
equation in which the missing particle must be determined.
Examples:
37
18Ar
+
0
−1e
X
Top (mass) number of X (37) must equal sum of 0+37 = 37
Bottom (charge) number of X (17) must equal sum of 18+-1=17
X is
37
17Cl
Complete Practice Problems #28-32.
WRITING DECAY EQUATIONS
On Reference Table N, you are given radioisotope symbols and their decay mode.
Concept Task : Be able to write or determine a balanced nuclear equation for a
radioisotope if its decay mode is known.
NOTE: this is generally done by piecing together information from Reference Table
N, O, and the P.T.
Examples
Write nuclear equations for the decay of Pu-239 and I-131.
Examples
Write nuclear equations for the decay of Pu-239 and I-131.
PRACTICE PROBLEMS
Predict the products of the following nuclear reactions:
(a) electron emission by 14C
(b) positron emission by 8B
(c) electron capture by 125I
(d) alpha emission by 210Rn
(e) gamma-ray emission by 56mNi
Complete Practice Problems #33-34 in Topic 12 Note packet
A half-life (t 1 ) is the period of time that must go by for half of the
2
nuclei in the sample to undergo decay.
During one half life period:
– Half of the radioactive nuclei in the
sample decay into new, more
stable nuclei.
• After 1st half life, (50%) of the original
amount of the sample will remain
undecayed
• After a 2nd half life, (25%) of the
original sample will remain undecayed
• After a 3rd half life, (12.5%) of the
original sample will remain undecayed
PLEASE RETRIEVE YOUR
NYS CHEMISTRY REFERENCE TABLE
OPEN TO PAGE 6
TABLE N
Complete Practice Problems #45-49 on page 234 in Topic 12:
Nuclear Chemistry note packet.
SOLVING HALF LIFE PROBLEMS
The half-life of Rn-222 (a carcinogenic house pollutant) is 3.8 days. If
today your basement contains 20.0 grams of Rn-222, how much will
remain after 19 days assuming no more leaks in?
You know how much of the isotope you have now, you want to find out how
much will be left after a certain amount of time (going into the future).
Step 1: Determine how many half-lives have gone by. Take how much
time has gone by and divide it by the duration of the half-life.
Step 2: Cut the amount (mass, percent, fraction, number of nuclei) in half
as many times as there are half lives.
The half-life of Rn-222 (a carcinogenic house pollutant) is 3.8 days. If
today your basement contains 20.0 grams of Rn-222, how much will
remain after 19 days assuming no more leaks in?
# half-lives =
time elapsed
half−life time
=
19 days
3.8 days
= 5 half-lives have gone by.
So, cut the starting amount (20.0 grams) in half 5 times!
20.0  10.0  5.0  2.5  1.25  0.625g is the final amount left
Exponential Decay Function
HALF-LIFE
You can use the following equation to calculate how
much of an isotope will remain after a given number of
half-lives.
n
1
A = A0 
2
• A stands for the amount remaining.
• A0 stands for the initial amount.
• n stands for the number of half-lives.
Using Half-Lives in Calculations
Carbon-14 emits beta radiation and decays with a half-life (t)
1
of 5730 years.
Assume
that
you
start
with
a
mass
of
2.00
×
2
10–12 g of carbon-14.
a. How long is three half-lives?
b. How many grams of the isotope remain at the end of three
half-lives?
The half-life of phosphorus-32 is 14.3 days. How many
milligrams of phosphorus-32 remain after 100.1 days if you
begin with 2.5 mg of the radioisotope?
n = 100.1 days ×
1 n
1 7
2 = (2.5 mg) 2
1
= (2.5 mg) 128
()
A = A0
1 half-life
= 7 half-lives
14.3 days
()
( ) = 2.0 × 10
–2
mg
A laboratory sample of P-32 triggers 400 clicks per minute in a GeigerMueller counter. How many days will it take for the P-32 to decay enough
so that there are only 50 clicks per minute?
For this one, you need to find out how many half-lives it takes for the counter to go
from 400 to 50 clicks per minute. Cut 400 in half until you get to 50:
400  200  100  50
So, you needed to cut 400 in half THREE times to get to 50, so 3 half-lives have gone by.
Now, look up the half-life of P-32 on Reference Table N. It’s 14.3 days. That’s how long
each half-life is. If three of these half-lives have gone by:
14.3
days
half life
× 3 half-lives = 42.9 days to cut 400 counts per minutes down to 50
counts per minute.
A cylinder contains 5.0 L of pure radioactive Ne-19. If the cylinder is
left to sit for 103.2 seconds, what percent of out original sample of
Ne-19 will remain?
Look up the half-life of Ne-19 on Reference Table N: 17.2 seconds.
# half-lives =
time elapsed
half−life time
=
103.2 days
17.2 seconds
= 6 half-lives have gone by.
When we started, 100% of the sample was pure Ne-19. So, cut 100 in half 6
times to find the percent remaining:
100  50  25  12.5  6.25  3.125  1.5625% of the original sample is
still pure, undecayed Ne-19
Complete Practice Problems #50-55 on page 235 in Topic 12:
Nuclear Chemistry note packet.
SOLVING HALF LIFE PROBLEMS
The half-life of Tc-99m* (used to locate brain tumors) is 6.0
hours. If 10. micrograms are left after 24 hours, how much Tc99m was administered originally?
You know how much of the isotope you have now, you want to find out
how much there was a certain amount of time ago (going into the past).
Step 1: Determine how many half-lives have gone by. Take how
much time has gone by and divide it by the duration of the half-life.
Step 2: Double the amount(mass, percent, fraction, number of
nuclei) as many times as there are half-lives.
The half-life of Tc-99m* (used to locate brain tumors) is 6.0 hours. If
10. micrograms are left after 24 hours, how much Tc-99m was
administered originally?
# half-lives =
time elapsed
half life time
=
24 hours
6.0 hours
= 4 half lives have gone by.
So, double the starting amount (10. micrograms) 4 times?
10.  20.  40.  80.  160. micrograms was the original amount
administered.
If a patient suffered complications due to overdose, and it is found that the doctor
game more Tc-99m than was necessary, the doctor will be in for a bit of trouble.
* The “m” indicates “metastable”, which means it only gives off gamma rays, not alpha,
beta or positron particles.
A laboratory sample of P-32 triggers 100. clicks per minute in a
Geiger-Mueller counter. How many days ago did the P-32 take to
decay enough to produce 1600. clicks per minute?
Find out how many half-lives it takes for the counter to go from 400 to 100 clicks per
minute. Cut 1600 in half until you get to 100:
1600  800  400  200  100
You needed to cut 1600 in half FOUR times to get to 100, so 4 half-lives have gone by.
Now, look up the half-life of P-32 on Reference Table N. It’s 14.3 days. That’s how
long each half-life is. If four of these half-lives have gone by:
days
14.3
x 4 half-lives = 57.2 days ago, the counter would have read 1600 clicks
half life
per minute.
Complete Practice Problems #64-71 on page 237 in Topic 12:
Nuclear Chemistry note packet.
SOLVING HALF LIFE PROBLEMS
A radioactive sample is placed next to a Geiger counter and
monitored. In 20.0 hours, the counter’s reading goes from 500
counts per minute to 125 counts per minute. How long is the halflife?
You want to find out how long the half-life is, knowing how much a sample has
decayed over a given amount of time.
Step 1: Determine how many times you can cut your original amount in
half in order to get to your final amount. This is the number of half-lives
that have gone by.
Step 2: Divide the time that has elapsed by the number of half-lives that
have passed.
A radioactive sample is placed next to a Geiger counter and
monitored. In 20.0 hours, the counter’s reading goes from 500
counts per minute to 125 counts per minute. How long is the halflife?
First, found out how many half-lives it will take for the counter to go from 500
to 125 counts per minute:
500  250  125
You needed to cut 500 in half TWO times to get to 125, so 2 half-lives have gone
by.
Half-life =
time elapsed
# of half−lives
=
20.0 hours
2 half−lives
= 10.0 hours per half-life
A sample of pure radioactive isotope is left to decay. After 40.0 days,
the sample is placed in a mass spectrometer, and it is determined
that the sample only 25% of the original isotope remains. How long
is the half-life?
First, find out how many half-lives it will take for 100% of a sample to decay to
25%:
100  50  25
It takes TWO half-lives for the sample to decay from 100% to 25%.
Half-life =
time elapsed
# of half−lives
=
40.0 days
2 half−lives
= 20.0 days per half-life
Complete Practice Problems #56-63 on page 236 in Topic 12:
Nuclear Chemistry note packet.
HALF LIFE
Comparing Half-Lives
Half-lives can be as short as a second or as long as billions of years.
Half-Lives of Some Naturally Occurring Radioisotopes
Isotope
Half-life
Radiation emitted
Carbon-14
5.73 × 103 years
b
Potassium-40
1.25 × 109 years
b, g
Radon-222
3.8 days
a
Radium-226
1.6 × 103 years
a, g
Thorium-234
24.1 days
b, g
Uranium-235
7.0 × 108 years
a, g
Uranium-238
4.5 × 109 years
a
HALF-LIFE
Comparing Half-Lives
Uranium-238 decays through a complex series of unstable
isotopes to the stable isotope lead-206.
• The age of uranium-containing
minerals can be estimated by
measuring the ratio of uranium238 to lead-206.
• Because the half-life of uranium238 is 4.5 × 109 years, it is
possible to use its half-life to
date rocks as old as the solar
system.
Uranium compounds are found in rocks and in soils that form
from these rocks. How can these uranium compounds lead to
a buildup of radon in homes and other buildings?
Radon gas is a product of the
decay of uranium. As the
uranium compounds in the
soil beneath homes and
buildings decay, radon is
produced and seeps into the
structure.
Radiocarbon Dating
HALF-LIFE
Plants use carbon dioxide to produce carbon compounds,
such as glucose.
• The ratio of carbon-14 to other carbon isotopes is
constant during an organism’s life.
• When an organism dies, it stops exchanging carbon
with the environment and its radioactive
14
6 C atoms decay without being replaced.
• Archaeologists can use this data to estimate when an
organism died.
Radiocarbon Dating
HALF-LIFE
The oldest rocks on Earth have been found to contain 50% U-238
and 50% Pb-206 (what does U-238 ultimately decay into.) What is
the age of these rocks?
Radioactive dating: used to determine the age of a substance that contains a
radioactive isotope of known half-life.
Step 1: Determine how many times you can cut your original amount in
half in order to get to your final amount. This is the number of half-lives
that have gone by.
Step 2: Multiply the number of half-lives by the duration of a half-life
(found on Reference Table N).
The oldest rocks on Earth have been found to contain 50% U-238
and 50% Pb-206 (what does U-238 ultimately decay into.) What is
the age of these rocks?
First, find out how many half-lives have had to go by so that you have gone from
100% U-238 to 50% U-238:
100  50
ONE half-life has gone by
Age of sample = # Half-lives x Half-life duration (found on Table N)
What is the half-life of U-238, according to Table N?
4.51 × 109 years
Age of sample = # half-lives x half-life duration
1 half-life x (4.51 × 109 years)
= 𝟒. 𝟓𝟏 × 𝟏𝟎𝟗 years old
An ancient scroll is discovered, and it is found that only 25% of the
original concentration of C-14 (a radioactive isotope found in equal
concentration in all living beings) remains. How old is the scroll?
First, find out how many half-lives have had to go by so that you have gone from
100% C-14 to 25% C-14:
100  50  25
TWO half-lifes has gone by
What is the half-life of C-14, according to Table N? 5730 years
Age of sample = # half-lives x half-life duration
2 half-lifes x (5730 years)
= 𝟏𝟏, 𝟒𝟔𝟎 years old
Radioactive Isotope
Use
C-14
Used to determine the age of biological remains
(archaeology)
I-131
Used to detect and cure hyperthyroidism (overactive
thyroid)
Co-60
Used as a source of radiation for radiotherapy of cancer
Tc-99m
Used to image blood vessels, especially in the brain, to
detect tumors
Pu-239
Used as a highly fissionable fuel source to nuclear power or
nuclear weapons
Am-241
Used in tiny amounts in smoke detectors as a source of ions
to make a current
U-235
Used as fissionable fuel source for nuclear power or nuclear
weapons
U-238
Used to determine the age of uranium-containing rock
formations (geology)
DECAY SERIES
• During a decay series, a
radioactive nucleus continuously
decays by releasing alpha and
beta particles until a stable
nucleus is produced.
• Uranium-238 decay series is
one of the most common decay
series. At the end of the decay
series, uranium-238 will decay
to lead-206 (a stable nucleus/
Atomic # 82).
DECAY SERIES
• The graph shows the decay series of Th-230. Each decay by alpha or beta leads
to a new isotope until a stable Pb-206 isotope is produced.
• Complete Practice Problem #21 in Topic 12: Nuclear Chemistry Note Packet.
• Nuclear Decay Series Worksheet1
FRACTION REMAINING ½ LIFE
Fraction remaining expresses the remaining mass of a radioisotope in terms of
ratio.
Fraction remaining of a radioisotope can be calculated when certain information
is known of a decaying process.
1. Fraction Remaining from number of half-life
periods (n)
2. Fraction remaining from length of time (t)
and half-life (T)
FRACTION REMAINING ½ LIFE
Complete Practice Problems #72-79 on page 238 in Topic 12: Nuclear Chemistry
note packet.
IDENTIFYING RADIOISOTOPES
When certain information about a decaying process is known, you can
identify which radioisotope on Table N the information is referring.
Keep the following in mind when comparing the isotopes given
as choices
Decays to greatest extent
• Shortest half-life
Decays to least extent
• Longest half-life
Smallest remaining %
• Shortest half-life
• Smallest mass
Largest remaining %
• Longest half-life
• Greatest mass
Answer Practice Problems #80-82 in Topic 12 note packet, pg239
FISSION
VS
FUSION
FISSION
When the nuclei of certain isotopes are
bombarded with neutrons, the nuclei
split into smaller fragments.
Neutron
91
36
Kr
Krypton-91
3
235
92
U
Uranium-235
(fissionable)
236
92
U
Uranium-236
(very unstable)
1
0
n
142
56
Ba
Barium-142
• More neutrons are released by the fission.
• These neutrons strike the nuclei of other uranium-235
atoms, which causes a chain reaction.
FISSION
In a chain reaction, some of the emitted neutrons
react with other fissionable atoms, which emit
neutrons that react with still more fissionable
atoms.
FISSION
Nuclear fission can release enormous amounts of energy.
• The fission of 1 kg of uranium-235 yields
an amount of energy equal to that
produced when 20,000 tons of dynamite
explode.
• An atomic bomb is a device that can
trigger an uncontrolled nuclear chain
reaction.
• Nuclear reactors use controlled fission to
produce useful energy.
FISSION
• A large fissionable (splittable) nucleus absorbs slow moving neutrons
– The large nucleus is split into smaller fragments, with release of more neutrons
• Tons of nuclear energy is released. Energy is converted from mass.
– Energy released is less than that of fusion reactions
• In nuclear power plants, the fission process is well controlled.
– Energy produced is used to produce electricity
• In nuclear bombs, the fission process is uncontrolled
– Energy and radiations released are used to cause destruction
• Nuclear wastes are also produced.
– Nuclear wastes are dangerous and pose serious health and environmental problems
– Nuclear wastes must be stored and disposed of properly
FUSION
Occurs when nuclei combine to produce a
nucleus of greater mass.
• The energy emitted from the sun involves nuclear fusion
• Hydrogen nuclei (protons) fuse to make helium nuclei.
• The reaction also produces two positrons.
FUSION
Fusion reactions, in which small nuclei
combine, release much more energy than
fission reactions, in which large nuclei split
apart and form smaller nuclei.
FUSION
• Two small nuclei are brought together under extremely high temperature and
pressure
– The two nuclei are fused (joined) to create a slightly larger nucleus
• Tons of nuclear energy are released. Energy is converted from mass.
– Energy released is much greater than that of fission reaction.
• Fusion produces no nuclear waste, unlike fission
• Energy from the sun is due to fusion reactions that occur in the core of the sun.
• High temperature and high pressure are required for a fusion reaction to occur.
– High temperature and pressure are necessary to overcome the repelling force of the two
positive nuclei that are to be fused
– Recall that the nucleus is positively charged. In fusion, two positive nuclei must be
brought (joined) together. Opposites attract, BUT like charges repel. Therefore, extremely
high temperature and pressure are needed to make two positively charged nuclei join
together in a fusion reaction.
Choose the correct words for the spaces. In solar
fusion, _______ nuclei fuse to form _______
nuclei.
Hydrogen nuclei fuse to form helium nuclei.
FISSION & FUSION
• Answer Practice Problems #24-27 in Topic 12: Nuclear Chemistry note packet. Pg 229-230
FUSSION
FUSION