1. Nuclear Chemistry
Bravo – 15,000 kilotons

2. Nuclear Symbols Mass number (p+ + no) Element symbol Atomic number
(number of p+)

3. Types of Radioactive Decay2+
alpha production (a): helium nucleus
beta production (b): neutron splits into an electron and a proton

4. CREATING A REACTION (α-particle)
On either side of the arrow, the mass number and atomic number MUST be the same (alpha-particle is always a helium nucleus)
238U  4He + 234Th
On the left side, mass number is 238
On the right side, = 238
On the left side, the atomic number is 92
On the right side, = 92

5. CREATING A REACTION (β-particle)
Both sides of the reaction still need to balance.
In beta-radiation, a neutron splits apart to form an electron and a proton
234Th + 234Pa  0e
On the left side, mass number is 234
On the right side, = 234
On the left side, the atomic number is 90
On the right side, = 90

6. Alpha Radiation
Limited to VERY large nucleii.

7. Beta Radiation
Converts a neutron into a proton.

8. PRACTICE
Each of the following compounds emits an alpha particle, write the balanced nuclear reaction
222Ra 88
208Po 84

9. PRACTICE
Each of the following compounds emits a beta particle, write the balanced nuclear reaction
14C 6
131I 53

10. Types of Radioactive Decay
gamma ray production (g):
positron production:
electron capture: (inner-orbital electron is captured by the nucleus)

11. GAMMA RADIATION
Gamma radiation does not produce any particles by itself
It is tied to another radioactive decay
Because the release of radioactive particles “frees” some energy in the nucleus, this energy takes the form of gamma radiation
There is a lot of energy holding the nucleus together so gamma radiation has a LOT of energy

12. Positron and Electron capture
Positron emissions occur when a proton splits apart into a neutron and an electron
Therefore the mass number does not change, but the atomic number changes the element into something new
Electron capture occurs when a proton “captures” one of the inner valence electrons and converts it into a neutron
This causes the release of a powerful neutrino (as powerful as gamma radiation)

13. TRY THESE
The following go through a positron emission. Write the balanced reaction:
17F 9
31S 16

14. TRY THESE
The following go through an electron capture. Write a balanced equation.
76Kr 36
125I 53

15. ANOTHER WAY TO SYMBOLIZE ISOTOPES
So far we have seen one way to symbolize isotopes:
17F 9
31S 16
Since we know the number of protons, we can symbolize the isotope with just the mass number:
Fluorine-17
Sulphur-31

16. Types of Radiation

17. Deflection of Decay Particles
Opposite charges_________ each other.
attract
repel
Like charges_________ each other.

18. Nuclear Stability
Decay will occur in such a way as to return a nucleus to the band (line) of stability.

19. HALF LIFE
When an isotope goes through a radioactive emission, it does so at a fairly constant rate
Scientists use this property to date items
Half-life: The time it takes for ½ of a radioactive isotope to decay to a stable form
Example: Carbon-14 has a half life of 5730 years
It takes 5730 years for ½ of radioactive Carbon-14 to decay to the stable form or Nitrogen-14
14C  0e + 14N

20. Half-life Concept

21. HOW TO SOLVE HALF-LIFE
Iodine-131 is used to destroy thyroid tissue in an over-productive thyroid gland. The half-life of iodine-131 is 8 days. If a hospital received a shipment of 200g of iodine-131, how much iodine-131 would remain after 32 days?

22. SOLUTION Step 1: Find out how many ½-lives have occurred
(32 days/8 days for half-lives)
4 half-lives
Step 2: Four each half-life, divide the sample by 2
4 half lives = ½ x ½ x ½ x ½ = 1/16
Step 3: Divide the initial sample size
200g/16 = 12.5g will remain

23. TRY THIS
Mercury-197 is used for kidney scans and has a half-life of 3 days. If the 32g of mercury-197 is ordered, but takes 15 days to arrive, how much would arrive with the shipment?

24. Sample Half-Lives

25. A radioactive nucleus reaches a stable state by a series of steps
A Decay Series

26. Nuclear Fission and Fusion
Fusion: Combining two light nuclei to form a heavier, more stable nucleus.
Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.

27. Energy and Mass
Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:
DE = Dmc2
Dm = mass defect
DE = change in energy
c = speed of light
Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.

28. Fission

29. Fission Processes
A self-sustaining fission process is called a chain reaction.

30. A Fission Reactor

31. Fusion

32. MORE PRACTICE PROBLEMS
Nitrogen-13 emits beta radiation and decays to Carbon-13. This has a half-life of 10 minutes. You start with 2.0g of Nitrogen-13:
Write out the balanced nuclear reaction.
Calculate how much nitrogen-13 is remaining after 40 minutes.

33. MORE PRACTICE PROBLEMS
Manganese-56 decays with beta radiation and has a half-life of 2.6 hours. You begin with 1mg of Manganese-56:
Write the balanced nuclear reaction.
How much manganese-56 is left after 10.4 hours?