1. Nuclear Chemistry

2. Introduction to Nuclear Chemistry
Nuclear chemistry is the study of the structure of and the they undergo.
atomic nuclei
changes

3. Chemical vs. Nuclear Reactions
Chemical Reactions
Nuclear Reactions
Bonds are broken
Nuclei emit particles and/or rays
Atoms are rearranged
Atoms change into atoms of different element
Involve valence electrons
Involve protons, neutrons, and/or electrons
Small energy changes
Large energy changes
Reaction rate can be changed.
Reaction rate cannot be changed

4. 3 Main Types of Radioactive Decay
Alpha a
Beta b
Gamma g

5. Alpha radiation Composition – Alpha particles, same as helium nuclei
Symbol – Helium nuclei, He, α
Charge – 2+
Mass (amu) – 4
Penetrating power – low (0.05 mm body tissue)
Shielding – paper, clothing 4 2

6. Alpha Decay
Uranium Thorium

7. Alpha Decay

8. Beta radiation Composition – Beta particles, same as an electron
Symbol – e-, 0-1β
Charge – 1-
Mass (amu) – 1/1837 (practically 0)
Penetrating power – moderate (4 mm body tissue)
Shielding – metal foil

9. Beta Decay
Thorium Protactinium

10. Beta Decay

11. Gamma radiation Composition – High-energy electromagnetic radiation
Symbol – ooγ
Charge – 0
Mass (amu) – 0
Penetrating power – high (penetrates body easily)
Shielding – lead, concrete

12. Type of Radioactive Decay
Review
Type of Radioactive Decay
Particle Emitted
Change in Mass #
Change in Atomic #
Alpha
α He -4 -2
Beta
β e +1
Gamma γ 4 2 -1

14. Which is more penetrating? Why?

15. BALANCING NUCLEAR EQUATIONS
1.The sums of mass numbers (left superscripts) on each side must be equal.
2.The sums of atomic numbers or nuclear charges (left subscripts) on each side of the equation must be equal.
Examples:
238U  4He Th
214Pb  0 b Bi

16. Balancing Nuclear Equations
Complete the following nuclear equations:
At Bi + ?
Th b + ? -1
Tl b + ?
4He 2 85 83
231Pa 91 90
208Pb 82 81

17. half Half-life time Half-Life
is the required for of a radioisotope’s nuclei to decay into its products.
For any radioisotope,
# of ½ lives
% Remaining
100% 1
50% 2
25% 3
12.5% 4
6.25% 5
3.125% 6
1.5625%

18. Half-Life

19. Half-Life
For example, suppose you have 10.0 grams of strontium – 90, which has a half life of 29 years. How much will be remaining after x number of years?  
You can use a table:
# of ½ lives
Time (Years)
Amount Remaining (g) 10 1 29 5 2 58
2.5 3 87
1.25 4
116
0.625

20. Problem A sample of 3x107 Radon atoms are trapped
in a basement that is sealed. The half-life of
Radon is 3.83 days. How many radon atoms
are left after 31 days?
answer:1.2x105 atoms (rounded) or atoms (unrounded)

21. Half-Life
If gallium – 68 has a half-life of 68.3 minutes, how much of a mg sample is left after 1 half life? ________
2 half lives? __________ 3 half lives? __________
Answer: 80 mg, 40 mg, 20 mg

22. Half-Life
Cobalt – 60, with a half-life of 5 years, is used in cancer radiation treatments. If a hospital purchases a supply of 30.0 g, how much would be left after 15 years? ______________
Answer: 3.75 g

23. Half-Life
Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is days. How much of a mg sample will remain after days? ______________
Answer: .25 mg

24. Half-Life
The half-life of polonium-218 is 3.0 minutes. If you start with 20.0 g, how long will it take before only g remains? ______________
Answer: 12 minutes

25. Half-Life
A sample initially contains mg of radon After 11.4 days, the sample contains mg of radon Calculate the half-life.
Answer: 3.8 is the half-life

26. changed nucleus Large energy
Nuclear Reactions
Characteristics:
Isotopes of one element are into isotopes of another element
Contents of the change
amounts of are released
changed
nucleus
Large
energy

27. Nuclear Reactions Fission = the splitting of nuclei
Two types:
Fission = the splitting of nuclei
Fusion = the joining of nuclei (they fuse together)
Both reactions involve extremely large amounts of energy
Albert Einstein’s equation E = mc2 illustrates the energy found in even small amounts of matter

28. Fission splitting two equal Chain split slowly nuclear reactors speed
Nuclear Fission
Fission
splitting
of a nucleus
- Very heavy nucleus is split into approximately fragments
reaction releases several neutrons which more nuclei
- If controlled, energy is released
(like in ) Reaction control depends on reducing the of the neutrons (increases the reaction rate) and
extra neutrons ( creases the reaction rate).
two
equal
Chain
split
slowly
nuclear reactors
speed
absorbing de

29. Nuclear Fission Disadvantages Advantages
Produces high level radioactive waste that must be stored for 10,000’s of years.
Meltdown causes disasters like in Japan and Chernobyl.
Advantages
Zero air pollution
Not a fossil fuel so doesn’t contribute to climate change

30. Nuclear Fusion - Fusion: Combining of two nuclei
- Two light nuclei combine to form a single heavier nucleus
- Does not occur under standard conditions (positive nuclei repel each other)
- Advantages compared to fission – No radioactive waste, inexpensive ,
- Disadvantages - requires large amount of energy to start, difficult to control.
- Examples – energy output of stars, hydrogen bomb, future nuclear power plants

31. Uses of Radiation
Radioactive dating: Carbon–14 used to determine the age of an object that was once alive.
Detection of diseases: Iodine–131 used to detect thyroid problems, technetium–99 used to detect cancerous tumors and brain disorders, phosphorus – 32 used to detect stomach cancer.
Treatment of some malignant tumors (cobalt–60 and cesium–137) cancer cells are more sensitive to radiation than normal, healthy cells

32. Uses of Radiation X-rays
Radioactive tracers: used in research to tag chemicals to follow in living organisms
Everyday items: thorium–232 used in lantern mantels, plutonium–238 used in long-lasting batteries for space, and americium–241 in smoke detectors.