What do they have in common?
Nuclear Chemistry
Nuclear Reactions
 Involve
the nucleus
 Radioactivity is
the spontaneous
emission of
radiation from an
atom
Nuclear Stability
Most atoms have a
stable nucleus
 A strong nuclear force
holds protons and
neutrons together
 Neutrons act as the
“glue” holding the
protons together

Belt of Nuclear Stability
There seems to
be a ratio of
protons to
neutrons that
increase the
chances that an
atom will be
stable.
Figure 18.1 The Zone of Stability
Types of Radiation
 The three main types of nuclear radiation are
alpha radiation, beta radiation, and gamma
radiation.
Radioactive Particles

Alpha particle - Helium nucleus with
no electrons
+2 charge
 Beta particle - High energy stream of
electrons
-1 charge
 Gamma Rays - High energy wave
which are the strongest
No charge
 Refer
to the radioactive particle
sheet that can be found on the
website for other particles.
A look at Alpha Decay
A look at Beta Decay
A look at Gamma Decay
Penetrating Powers
Nuclear Equations

Scientists use a nuclear equation when
describing radioactive decay

The mass number and atomic number
must add up to be the same on both sides
of the equation
Balancing Nuclear Equations

Here’s the equation from the previous slide.
The top numbers on the left side of the
arrow = the top numbers on the right side of
the arrow.
 The same holds for the bottom numbers.
 USE A PERIODIC CHART for the atomic
numbers if needed.

Beta Decay
 Beta
decay results in an increase in
the atomic number.
 Notice
how the top numbers equal
and the bottom numbers also equal
Nuclear Stability and Decay
For the equations on
the right, the atomic
numbers are also shown
but in many equations
they are omitted
because they can be found
on the periodic chart.
For example, carbon is
often written as:
14C
Practice
 Write
the nuclear equation of the
alpha decay of Radon – 226
 Write the nuclear equation of the
alpha decay of Gold – 185
 The
number after the element is
the mass number.
Practice Answers
226
 Rn
 185Au

4He
+
 4He +
222Po
181Ir
Practice
Write the nuclear equation of the beta
decay of Iodine - 131
 Write the nuclear equation of the beta
decay of Sodium - 24

Practice Answers
131

I


24Na

1
e
-1
e1
-1
+
+
131Xe
24Mg
Half Life
 Radioisotopes
are radioactive isotopes
of elements (not all isotopes are
radioactive)
 A half-life is the amount of time it
takes for one half of a sample to
decay.
 The half-life is different for each
element and isotope.

http://www.colorado.edu/physics/2000/isotopes/r
adioactive_decay3.html
Beta Decay of Phosphorous - 32
Notice that every 14 days,
the amount is cut in half.
Radiocarbon Dating
Carbon - 14 undergoes
beta decay to form stable
nitrogen 14
 Half life of 5,730 years
 Used to approximate ages
100 – 30,000 years
 Other radioisotopes are
used to measure longer
periods of time

Parent and Daughter Nuclides
The term parent nuclide refers to the
original atom.
 The term daughter nuclide refers to the
particle that is produced after the
radioactive decay is completed.

Some examples of
Parent – Daughter Nuclides
Parent
Daughter
Half Change in...
Carbon-14
Nitrogen-14
5730 years
Uranium-235
Lead-207
704 million years
Uranium-238
Lead-206
4,470 million years
Potassium-40
Argon-40
1,280 million years
Thorium-232
Lead-208
14,010 million years
Rubidium-87
Strontium-87
48,800 million years
Practice
 The
half-life of Po-218 is three
minutes. How much of a 2.0 gram
sample remains after 15 minutes?

Remember that the symbol for half life is t1/2
Practice Answer
It is often best to set up a simple table
especially if the amount of time is a
multiple of the half life like in this
example.
 Notice that 15 minutes is a multiple of the
3 minute half – life.
 The next slide has the table that we need
to create to solve the problem.

Practice Answer: Half – Life Table
Amount of Material
Initially
Time elapsed
Amount of material
remaining
2 grams
2 grams
1 gram
.5 gram
.25 grams
.125 grams
0 minutes
3 minutes
6 minutes
9 minutes
12 minutes
15 minutes
2 grams
1 gram
.5 grams
.25 grams
.125 grams
.0625 grams
So after 15 minutes, there is only .0625 grams left.
Practice
 Three
grams of Bismuth-218 decay
to 0.375 grams in one hour.
 What is the half-life of this isotope?
Practice Answer Half – Life Table
We can also create the table going backwards to
answer questions like this one.
Notice it is really a similar table.
Amount of Material
Initially
Number of half-lives
Amount of material
remaining
3 grams
1
1.5 grams
1.5 grams
2
.75 grams
.75 grams
3
.375 grams
It took 3 half-lives to get to the amount .375 grams. If 1 hour
equals 3 half-lives, then each half-life must be 20 minutes.
More on Half - Life

Sometimes the amount of time is not a
multiple of number of half-lives.

We can use the following equation for all
half-life problems.
Nuclear Bombardment

Nuclear scientists change elements by
bombarding the nucleus with particles –
transmutation
14N

+
4He

17O
+
1H
Leads to the creation of transuranium
(after U) elements.
Transmutation Reactions
 The first artificial transmutation reaction involved
bombarding nitrogen gas with alpha particles.
Fermilab Particle Accelerator
Nuclear Power
Nuclear Reactors use fission of Uranium-235
as source of energy
 A large nucleus is split into two smaller
nuclei
 A small amount of mass is converted to a
tremendous amount of energy (E = mc)2
 About 1 kg of Uranium-235 = 2.2 million
gallons of gasoline
 http://people.howstuffworks.com/nuclearpower2.htm

Nuclear Fission
 Nuclear Fission
Fission Produces a Chain Reaction
Overview of a nuclear power plant
All power plants work on the same
principal. It needs to heat up water to
make steam to run a steam engine which
produces the actual electricity. The only
difference between a coal power plant and
a nuclear power plant is that the first
burns coal to heat the water and the
second controls a nuclear reaction to heat
the water.
Nuclear Power Plants # 1
• A nuclear plant has some differences of
course compared to a coal burning plant.
• The fuel is much more costly, though lasts
much longer.
• The heat can be controlled easily in a coal
burning plant by simply controlling how
much coal is added to the fire.
• This is the primary difference and the
biggest safety concern in a nuclear
power plant as the next slide shows.
Nuclear Power Plants # 2
 Uranium fuel can’t be removed or limited like a
coal fired power plant.
 The heat comes from the chemical reaction of the
decay of a uranium atom.
 The atom splits and the chain reaction keeps it
going.
 The way to control the heat released is by
controlling the neutrons released
during the chain reaction.
This is done by using graphite rods that can be
raised and lowered which controls the amount
of neutrons absorbed at any time.
Nuclear Power Plants # 3
•This was the primary problem in developing the
atomic bomb during World War 2.
Both sides knew how to get the fission process of
the uranium going, but the questions were on how
to keep it under control so it wouldn’t go off too
early in the lab.
There were two teams. One team was working for
Germany. The other team was a group of mostly
German scientists who were able to flee Germany
to the United States and were working for the Allied
forces.
Nuclear Power Plants # 4
The team working in Germany focused on
using heavy water to moderate the chain
reaction.
Heavy water is regular water but with a
difference in the hydrogen isotope. Regular
water is mostly 1H but heavy water is 2H. This
extra neutron helps to absorb other neutrons
and control the reaction. Regular water is
about .0001 % heavy water but the
percentage needed is about 98 % so it took
time to get enough heavy water needed.
Nuclear Power Plants # 5
The allied side, based in the United States
decided to use graphite rods which could be
raised and lowered and absorb the neutrons.
While both were acceptable ways to
moderate the reaction, the Allied side was
able to create the bomb first and force an
end to the war.
A Schematic Diagram of a Reactor Core
Gun-triggered fission bomb
(Little Boy - Hiroshima)
Implosion-triggered fission bomb
(Fat Man - Nagasaki)
http://people.howstuffworks.com/nuclear-bomb5.htm
Nuclear Power Plants # 6
An interesting side note to all of this is how nuclear
energy in power plants came to be.
The scientists who were working on the bomb were
uneasy with this type of power and the US
government put out a survey to ask how can this
energy source by used peacefully. Some answers such
as to create a new Panama Canal were tossed aside
(too much residual radiation). Suggestions were that
if the reaction can be controlled it can be used to run
steam turbines in power plants.
This led to the start of the nuclear power plant.
A schematic of a nuclear power plant
What the heat from the radioactive process does is to heat
water to run a turbine.
Nuclear Fusion
Atomic nuclei fuse releasing a
tremendous amount of energy
Nuclear Weapons

The bombs dropped in World War 2 were
fission bombs made of Uranium and getting
their energy when the Uranium atoms split
(fission) into smaller atoms.
This is called an Atomic Bomb.

Since then, the process of taking Hydrogen
atoms and combining 4 of them to create a
Helium atom (fusion) has been developed.
This creates a more powerful bomb.
This is called a Nuclear Bomb.
Radiation and You
SI units are in Curies (Ci)
 One Curies is amount of nuclear
disintegrations per second from one gram
of radium
 Also measured in rem (Roentgen Equivalent
for Man)
 Over 1000 rem is fatal
 The next slide gives a glimpse of the
radiation we receive. NOTE that the units
are MILLIREMS, which is 1/ 1,000 of a REM.

Radon Gas
Figure 18.2 A Decay Series
Detecting Nuclear Radiation
You cannot hear or
feel nuclear radiation.
 Geiger Counter
 Film badges
