1. Nuclear Chemistry
“Nuclear radiation is in the form of elementary particles emitted by an atomic nucleus, as alpha rays, beta rays, or gamma rays, produced by decay of radioactive substances or by nuclear fission.”

2. Absorption of Radiation
 = alpha particle Weak energy
 = beta particle Moderate energy
 = gamma radiation High energy
Timberlake, Chemistry 7th Edition, page 84

3. Characteristics of Some Ionizing Radiation
Characteristics of Some Ionizing Radiations
Property Alpha radiation Beta radiation Gamma radiation
Composition
Alpha particle
(helium nucleus)
Beta particle
(electron)
High-energy electro-
magnetic radiation
Symbol
a, He-4
b, e g
Charge 2+ 1-
Mass (amu) 4
1/1837
Common source
Radium-226
Carbon-14
Cobalt-60
Approximate
energy
5 MeV*
0.05 to 1 MeV
1 MeV
Penetrating
power
Low (0.05 mm
body tissue)
Moderate (4 mm
body tissue)
Very high (penetrates
body easily)
Shielding
Paper, clothing
Metal foil
Lead, concrete
(incompletel shields)
*(1 MeV = x J)

4. RADIOACTIVITY
Spontaneous emission of particles (alpha, beta, neutron) or radiation (gamma), or both at the same time, from the decay of certain radioisotopes.
Isotopes of some elements are radioactive, especially the large elements.
Radioactive elements are unstable and will undergo radioactive decay.
These radioactive elements release particles (alpha and beta) in order to stabilize.
Radioactive decay results in the release of particles and the formation of an isotope of a new element.
In additions to particles being released, sometimes gamma radiation is released.

5. HALF LIFE Amount of time it takes to decay ½ of a sample.
Varies from milliseconds to billions of years.
Start with 1.6 g of 187Er with a half-life of 400 seconds.
How many grams after 3 half-lifes?
This is always the slope on a half life graph
How much time does it take to have grams?
How many half-lifes to get to ?

6. HALF LIFE Number of half life Mass Time s % Fraction/ ratio 1.6 100 1
1.6
100 1
0.8
400 50 .5 2
0.4
800 25
.25 3
0.2
1200
12.5
.125 4
0.1
1600
6.25
.0625 5
0.05
2000
3.125
.03125 6
0.025
2400
1.5625
You can make a chart to determine the mass, number of half life, time, percent and fraction remaining.
Number of half life, %, and Fraction are the same on every chart.

7. HALF LIFE How to fill in the chart
1.Number of half life- add 1 to each row.
2.Mass-Divide each row’s mass by 2
3.Time-Add time to each row.
4.%- always start with 100 at 0 time and divide each row by 2.
5. Fraction or ratio- always start with 1 and divide each row by 2.
1.Number of half life
2.Mass
3.Time s
4.%
5.Fraction/ratio
1.6
100 1
0.8
400 50 .5 2
0.4
800 25
.25 3
0.2
1200
12.5
.125 4
0.1
1600
6.25
.0625 5
0.05
2000
3.125
.03125 6
0.025
2400
1.5625

8. HALF LIFE
A radioisotope will decay ½ of the mass of its sample during the first half life.
 The mass of the radioactive sample is ½ of the starting mass.
 The mass of the non-radioactive sample has increased.
What is the half life of the sample?
If the starting mass was 10 g, how many g remain after 30 years?
How many years will it take to reduce the sample to g?

9. ALPHA DECAY
Alpha decay is the process of releasing an alpha particle (He nucleus) from the nucleus of a radioisotope.
The result of alpha decay is a reduction of the mass number by 4 and the atomic number by 2
The equation is written using isotope notation.
Both sides of the arrow are equal in mass and number of protons

10. Alpha Decay Release of an alpha particle, He nucleus.
Release of an alpha particle, He nucleus.
Alpha Decay
Timberlake, Chemistry 7th Edition, page 87

11. ALPHA DECAY
240 Pu 236U + 4He
All numbers are equal on each side of the arrow. u
 240
The addition of the mass numbers on the left and right of the arrow are equal.
The addition of the atomic numbers on the left and right of the arrow are equal.

12. Beta decay is the release of a beta particle (electron) from the nucleus of an atom.
WHAT??? How does an electron come out of the nucleus if they are in the energy levels??? 56
Are you ready for this? A neutron changes into a proton and an electron. After all, a positive and a negative make it neutral.
The product of this decay is an atom with the same mass but 1 more proton and an electron.

13. Beta Decay
Changes a neutron into a proton and an electron. The electron is released as a beta particle.
Timberlake, Chemistry 7th Edition, page 90

14. Alpha and Beta Emission
Alpha Decay
ALPHA
Element down 2 protons and mass of 4
BETA
Element increases 1 proton and keeps same mass
Beta Decay

15. Alpha and Beta Emission

16. BETA PLUS DECAY The symbol for a positron is e+.
Are you sitting down?
Now we have a POSITIVE electron. It is called a positron.
Positron decay is like a mirror
image of beta
decay.
A proton to become a neutron.
It emits a positron
3) The atomic number goes DOWN by one and mass number remains unchanged.
The symbol for a positron is e+.
PET-positron emission tomography is a scan used to find cancer.

17. ELECTRON CAPTURE
Electron capture is not like any other decay - alpha, beta, or position. All other decays shoot something out of the nucleus.
1) An electron from the closest energy level falls into the nucleus, which causes a proton to become a neutron.
2) A neutrino(neutral particle with no mass) is emitted from the nucleus.
3) The atomic number goes down by 1 and mass number stays the same.

18. New Radioactive Isotope
IMPORTANT: MASS AND CHARGE = ON BOTH SIDES OF ARROW!
4+10 = 13+1
2+5 = 7+0
New Radioactive Isotope
Timberlake, Chemistry 7th Edition, page 92

19. NUCLEAR FISSION
Nuclear Fission is the splitting of a radioactive isotope by bombardment with neutrons so that the atom splits into smaller elements with a release of energy.

20. NUCLEAR FISSION
When a nucleus fissions, it splits into several smaller fragments. These fragments, or fission products, are about equal to half the original mass. Two or three neutrons are also emitted.
The sum of the masses of these fragments is less than the original mass. This 'missing' mass (about 0.1 percent of the original mass) has been converted into energy according to Einstein's equation.
Fission can occur when a nucleus of a heavy atom captures a neutron, or it can happen spontaneously.

21. Fissionable U-235

22. A nuclear chain reaction occurs when one nuclear reaction causes an average of one or more nuclear reactions, thus leading to a self-propagating number of these reactions. The nuclear reaction is the fission of heavy isotopes.
The nuclear chain reaction is unique since it releases several million times more energy per reaction than any chemical reaction.
Chain reaction

23. Fission Process

24. NUCLEAR POWER PLANTS
Electricity in Illinois is about 50% coal generated and 50% nuclear power generated.

25. NULCEAR POWER ILLINOIS

26. Nuclear Reactor

27. Nuclear Power Debate Cons
Radiation exposure possible from accident or terrorist
No where safe to bury waste
Moving waste a potential danger
Thermal pollution
Long time to build nuclear plants
U will be depleted
Pros
No greenhouse gases
 Very little solid waste
Less extensive mining to
extract U
 Less air pollution
 Generate large amounts of electricity from a single plant

28. Nuclear Fusion
4 H nuclei electrons 1 He Energy + + +

29. FISSION VS. FUSION FISSION Splits atoms Combines atoms
Releases radiation
Used in nuclear power plants
FISSION AND FUSION
Release of large amounts of energy
Changes in the nuclei of atoms
FUSION
Combines atoms
No radiation
On the sun
FISSION VS. FUSION

30. OTHER USES FOR RADIOISOTOPES
detect leaks in pipelines.
attacking abnormal cells or harmful bacteria.
treat cancer
preserve food
sterilize medical instruments
tracer in medical research
studies of human metabolism.
Military
home smoke detectors.
calculate the age of mineral
Pest control
OTHER USES FOR RADIOISOTOPES