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NUCLEAR CHEMISTRY
• DESCRIBE THE NUCLEAR COMPOSITION OF
UNSTABLE ISOTOPES AND THE RESULTING CHANGES
TO THE THEIR NUCLEAR COMPOSITION.
• IDENTIFY TYPES OF NUCLEAR EMISSION, INCLUDING
ALPHA PARTICLES, BETA PARTICLES, AND GAMMA
RADIATION
• DIFFERENTIATE BETWEEN FISSION AND FUSION.
• IDENTIFY USES AND POSSIBLE NEGATIVE SIDE
EFFECTS OF NUCLEAR TECHNOLOGY.
COS 11.0, 11.1, 11.2, 11.3
WHAT YOU’LL LEARN
• Identify three types of nuclear radiation and their
properties.
• Distinguish between fission and fusion, and provide
examples of each.
• List and explain three beneficial uses and three
possible risks of nuclear radiation.
• Contrast properties of radioactive and stable nuclei.
FYI: HISTORICAL PERSPECTIVE
• Henri Becquerel
• 1896 - Discovers natural
radioactivity
THE DISCOVERY OF RADIATION
In 1896 Henri Becquerel made an
important discovery.
He accidentally had placed a piece of uranium ore on top of an
unexposed photographic plate. Later, when the plate was
developed, the image of the rock was found on the plate.
Based on further experiments, he concluded that the plate had
been exposed by rays given off by the uranium.
MADAME CURIE DISCOVERS
RADIUM AND POLONIUM
Following Becquerel’s discovery, Marie
Sklodowska Curie and her husband,
Pierre Curie, attempted to isolate the
“radioactive” material from the uranium
ore.
In doing so they discovered two new elements, Radium and Polonium,
both of which were more radioactive than the original ore.
ERNEST RUTHERFORD
Rutherford investigated this new property of
matter and discovered that, in the process of
emitting radiation, atoms of one element
became atoms of another element.
Today, we describe the process of an atom of one element
becoming an atom of a different element as transmutation.
RUTHERFORD DISCOVERED THE
DIFFERENT TYPES OF RADIATION
Rutherford was the first to identify and name two different types of
radiation given off when an atom of one element underwent
transmutation and became an atom of another element. The two types
of radiation he found were:
•The alpha particle (a)
•The beta particle (b)
A third type of radiation that was discovered later is called:
•Gamma radiation (g)
NUCLEAR REACTIONS
• Involve changes in the composition of nuclei
• Accompanied by the release of tremendous amounts of
energy
• Where does this energy come from?
MASS DEFECT
• Some of the mass can be converted into energy
• Shown by a very famous equation!
E=mc2
Energy
Mass
Speed of light
NUCLEAR FISSION
• The splitting of a heavy nucleus into lighter nuclei
NUCLEAR FUSION
• The combination of light nuclei to produce a heavier
nucleus
Chapter 9
Nuclear Radiation
Radioactivity:
 process by which an
emits one or more particles or energy in form
of electromagnetic radiation.
nuclear radiation:
 particles that are released from nucleus
during radioactive decay.

What makes the nucleus unstable?
The neutron-to-proton ratio determines
the stability of the nucleus

For low atomic #’s:


Equal #’s of protons and neutrons
Above atomic #20:


More neutrons than protons
Note: this stability has nothing to do with
electrons and valence shells (we’re talking
about nucleons)
Nuclides



Different atomic forms of all elements
(isotopes)
Most small nuclides have equal # of
protons and neutrons
Some nuclides have “magic #’s” of
protons and neutrons and are especially
stable
NUCLEI WHOSE NEUTRON-TO-PROTON RATIO IS UNSTABLE
UNDERGO RADIOACTIVE DECAY BY EMITTING 1 OR MORE
PARTICLES AND/OR ELECTROMAGNETIC RAYS:
NUCLEI WHOSE NEUTRON-TO-PROTON RATIO IS UNSTABLE
UNDERGO RADIOACTIVE DECAY BY EMITTING 1 OR MORE
PARTICLES AND/OR ELECTROMAGNETIC RAYS:
Type/
symbol
Alpha
4
Identity
Mass Charge Penetration
(amu)
a or 2 He
helium
nucleus
4.0026
2+
low
0
-1
b or e
electron
0.00055
1-
low-med
g
0
high
Proton 1p or 1H
1
1
high energy
0
radiation
proton,
1.0073
H nucleus
1+
low-med
Neutron
neutron
0
very high
Beta
Gamma
0
0
1
0
n
1.0087
NUCLEAR REACTIONS VS.
NORMAL CHEMICAL CHANGES
• Nuclear reactions involve the nucleus
• The nucleus opens, and protons and
neutrons are rearranged
• The opening of the nucleus releases a
tremendous amount of energy that holds
the nucleus together – called binding
energy
• “Normal” Chemical Reactions involve
electrons, not protons and neutrons
TYPES OF RADIATION
Alpha (ά) – a positively
charged helium isotope •
4
2
He
we usually ignore the charge because it
involves electrons, not protons and
neutrons
e
0
1
•Beta (β) – an electron
Gamma (γ) – pure energy;
called a ray rather than a
particle
0
0
0
g
PENETRATING ABILITY
Can be stopped by
a sheet of paper
BALANCING NUCLEAR REACTIONS
•In the reactants (starting materials –
on the left side of an equation) and
products (final products – on the right
side of an equation)
Atomic numbers must balance
and
Mass numbers must balance
•Use a particle or isotope to fill in the
missing protons and neutrons
ALPHA PARTICLES
consists of two protons and two
neutrons
• Composed of He nucleus atom w/ +2
charge
• Least penetrating type of radiation
• Can be stopped by a sheet of paper
23
BETA PARTICLES
• negatively charged electron emitted
during certain types of radioactive decay
• Emitted at high speeds from nucleus
• Beta decay
25
GAMMA PARTICLES
gamma ray
• high-energy photon emitted by a nucleus during fission
and radioactive decay
• Most penetrating type of radiation
• Does not have a charge nor mass
NEUTRON EMISSION
• consists of matter that is emitted from an
unstable nucleus.
• Neutrons are able to travel farther through
matter than either alpha or beta particles.
Nuclear Fission
• process by which a
nucleus splits into two
or more fragments and
releases neutrons and
energy.
• Produces nuclei of
lower mass than
reactants
• Used to produce nuclear
power (electricity)
• Produces extremely
toxic waste
Nuclear Fusion

process in which light nuclei
combine at extremely high
temperature, forming heavier,
more stable nuclei and
releasing energy.

Produces nuclei of higher mass
than reactants

Takes place in sun.

Helium major by product
Beneficial Uses of Nuclear Radiation
Smoke detectors
• small alpha-emitting isotope detects smoke particles
in air.
radioactive tracer:
•
•
radioactive material that is added to a substance so
that its distribution can be detected later.
understand biochemical processes in plants.
Radiotherapy:
•
treatment that uses controlled doses of nuclear
radiation for treating diseases such as cancer.
Nuclear Medicine: Imaging
Thyroid imaging using Tc-99m
Food Irradiation
•Food can be irradiated with g rays
from 60Co or 137Cs.
•Irradiated milk has a shelf life of 3 mo.
without refrigeration.
•USDA has approved irradiation of
meats and eggs.
Possible Risks of Nuclear Radiation
Ionization

change in number of electrons in an atom or
molecule, causing the particle to be positively or
negatively charged.
Radiation sickness

results from high levels of nuclear radiation.
Dosimeter

•
device that measures the amount of nuclear
radiation exposure.
Studies have shown a relationship between
exposure to high levels of nuclear radiation and
cancer.
POSSIBLE RISKS OF NUCLEAR RADIATION
Radon gas:
• colorless and odorless,
• produced by the decay of uranium-238
• naturally occurs in soil and rock.
• Causes lung cancer