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Nuclear Chemistry
Section 1: Basic Definitions
• Nuclear Chemistry
– The study of the atomic nucleus, its reactions and
radioactivity
• Radioactivity
– Spontaneous emission of particles and/or energy
during nuclear decay
Section 1, continued
• Nuclear Decay
– Spontaneous disintegration of a nucleus
– Results in a new element being formed
– Occurs when particles and/or energy escape from
an unstable nucleus
– Releases large amounts of energy
• Radiation
– Can refer to either the particles or energy released
during nuclear decay
Section 2:
Types of Radiation to Know
Radiation Description
Radiation Symbol
• Proton
1
• Proton: H
1
– Positively charged particle in the
nucleus of the atom
– Hydrogen nucleus
– Most cosmic rays are protons traveling
at the speed of light
• Neutron
1
• Neutron: n
0
– Neutral particle in the nucleus of the
atom
• Electron (Beta-minus particle)
– Negatively charged particle that moves
randomly in specific orbitals outside the
nucleus of an atom
• Electron:
0
e, β−1
Section 2, continued
Radiation Description
• Positron (Beta-positive particle)
– Anti-matter electron
– Same properties of an electron
except it has a positive charge
• Alpha Particle
– Helium nucleus
– 1st radioactive particle discovered by
Ernest Rutherford
• Gamma Radiation
– High energy electromagnetic
radiation
Radiation Symbol
0
• Positron: e, β+
1
4
• Alpha: He, α
2
0
• Gamma: γ
0
Section 3: Properties of Certain Types of Radiation
Property
Alpha Particle Beta-minus
particle
+2
-1
Beta-positive
particle
+1
Speed
Largest and
slowest form
of radiation
Faster than
Speed of light
alpha (same as
beta-minus)
Can be
stopped by…
Piece of paper Plastic,
aluminum foil
Charge
Faster than
alpha
Plastic,
aluminum foil
Gamma
Radiation
n/a
Thick lead or
concrete
Section 4: Isotopes
• Same element, different number of neutrons
• There are 2 ways to identify isotopes:
– Hyphen-Notation = element – mass #
• Example: oxygen – 16
– Chemical Configuration
• Example:
number
mass

 16
atomic


 8
number
O
2-
ioniccharge



Section 4, continued
• Isotopes of hydrogen have special names
• Deuterium and tritium are radioactive;
protium is not.
Section 4, continued
• Why are some isotopes radioactive and others
are not?
– The proton : neutron ratio determines whether an
isotope is radioactive
• Elements with atomic # ≤ 20 prefer a 1 : 1 ratio
• Elements with atomic # > 20 prefer a 1 : 1.5 ratio
• Transuranium elements =
– Elements with atomic # > uranium (92)
– All are radioactive
– In fact, all elements with atomic number > 83 are
radioactive!
Section 4 Example Problems
1. Write the hyphen-notation and the chemical
configuration for an iron atom that has 23
electrons and 32 neutrons.
Section 4 Example Problems,
continued
2. Write the hyphen-notation and determine
the number of protons, neutrons and
32
electrons for P.
15
Section 4 Example Problems,
continued
3. Write the hyphen-notation and chemical
configuration for the three isotopes of
hydrogen. Assume each isotope is neutral.
Section 5: Use of Carbon-14 in Radiocarbon Dating
Section 6: Nuclear Reactions v
Chemical Reactions
Nuclear Reactions
• Forms a new isotope or
different element
• Extremely large energy
changes
• Energy comes from the
binding energy of the
nucleus
• Involves a change in the
number of protons or
neutrons
Chemical Reactions
• Forms new substances
based on the elements
present in the reactants
• Small energy changes
• Energy comes from
breaking and forming
chemical bonds
• Involves valence electrons
Section 7: Writing Nuclear Reactions
Steps
1. Set up 2 equations: one
using the mass (top)
numbers and the other
using the atomic (bottom)
numbers.
2. Calculate the missing mass
number.
3. Calculate the missing
atomic number.
4. Use the atomic/mass #s to
determine the identity of
the missing particle.
Example
29Mg  0e + _________
−1
12
Mass #s:
29 = 0 + _____
Atomic #s:
12 = -1 + _____
Section 8: Alpha Emission
• A helium nucleus (2 p, 2 n) is emitted from the
nucleus
• Example: Alpha decay of 241Am
Section 8: Beta Emission
• A neutron is converted into a proton and
electron, then the electron (β- particle) is
emitted
• Example: Beta decay of 14C
Section 8: Positron Emission
• A proton is converted into a neutron and
positron, and the positron is emitted from the
nucleus
• Example: Positron Emission of 11C
Section 8: Electron Capture
• The nucleus captures an electron and
combines it with a proton to form a neutron
• Example: Electron capture by 7Be
Section 8: Gamma Emission
• Gamma rays are emitted during nuclear
reactions, either alone or with other types of
radiation
• Gamma rays do NOT change the mass number
or atomic number because they are energy
not matter.
240
240
Pu*
Pu
94
94
γ ray
Section 9: Decay Series
A series of nuclear reactions that occur until a stable nucleus is formed
The first 4 nuclear reactions
in the uranium-238 decay
series are:
238U

4 He
2
+
234Th
234Th

0 β
-1
+
234Pa
234Pa

0 β
-1
+
234U
4 He
2
+
230Th
234U

Section 10: Fission
• Definition
– heavier nuclei split apart to form lighter nuclei
• Occurs in…
– Nuclear power plants, nuclear bombs
• Chain Reaction (definition)
– neutrons produced from one reaction can hit
other isotopes to start a new fission reaction
• Example of Fission Reaction
1n + 235U  141Ba + 92Kr + 3 1n
92
56
36
0
0
Section 11: Nuclear Power Plant
Containment Structure (A)
-thick layers of concrete and steel to prevent radiation leakage
Control Rods (B)
-controls the rate of reaction; can be used to shut reaction down
Reactor (C)
-where the nuclear reactions take place
Steam Generator (D)
-nuclear reactions produce heat energy which is used to boil water
Turbine (H)
-steam runs the turbine, which causes the generator (G) to produce
electricity
Fuel Rods (K)
-usually contain uranium-235; the fuel for the nuclear fission reaction
Condenser (I)
-sends cool water to the cooling tower (J) and reactor; vital to keep
reactor from overheating
Section 11: Nuclear Power Plant
• A nuclear reactor is self-sustaining due to the
chain reaction. The neutrons that are produced
from one reaction cause a new fission reaction to
occur.
Section 12: Nuclear Power (Fission)
Pros and Cons
Pros
• No air pollution
• No greenhouse gas
emissions
• Low cost fuel because very
little is needed
• Can be done at room
temperature
Cons
• Expensive to build and
maintain
• Risk of accidents
• Security
• Thermal pollution (warm
water into streams and
rivers)
• Disposal of nuclear waste
(must be buried for possibly
thousands of years)
Section 13: Fusion Reaction
• Definition
– light nuclei combine (fuse) together to form
heavier nuclei
• Occurs in…
– the sun and other stars; hydrogen (fusion) bomb
• Example of Fusion Reaction
2H + 3H  4He + 1n
1
1
2
0
Section 14: Fusion Pros and Cons
Pros
• Produces even more energy
per gram of fuel than
fission.
• Produces less nuclear waste
than fission.
• Fusion fuel is easy to get.
(Heavy hydrogen is found in
water.)
Cons
• Does not sustain a chain
reaction.
• Requires extremely high
temperatures (108 - 109 °C)
and pressures.
• We do not have the
technology to efficiently
harness the energy
produced by fusion or to
contain a fusion reaction.