1. Nuclear Chemistry

2. Radioisotopes
Isotopes with unstable (or radioactive) nuclei
Gain stability by undergoing a nuclear rxn

3. Radioactive Decay
Spontaneous disintegration of a nucleus into a lighter nucleus, accompanied by the emission of particles and/or electromagnetic radiation

4. Radioactive Decay
A nucleus is unstable due to the proportion of neutrons to protons, as well as the overall size of the nucleus

5. Types of Radioactive Decay

6. Alpha Decay Alpha particles have 2 neutrons and 2 protons
These large particles do not travel too far and are stopped by paper or skin

7. Beta Radiation
Consists of fast moving electrons formed by decomposition of a neutron into a proton
The released electron is the beta particle
Beta particles have more penetrating power than an alpha particle, and can be stopped by aluminum foil or wood

8. Gamma Rays Often emitted with ß and a have no mass or charge
High energy electromagnetic radiation given off by a radioisotope
Often emitted with ß and a
have no mass or charge
stopped by several cm of lead or concrete

9. Comparison of a, b, g

10. Comparison of a, b, g

11. Comparison of a, b, g

12. Positron Emission
A particle that has the same mass as an electron but has a positive charge and is emitted from the nucleus in radioactive decay

13. Electron Capture
An inner orbital electron is captured by the nucleus of its own atom and combined with a proton to form a neutron

15. Particles in Radioactive Decay

16. Sources of Exposure
*Nuclear medicine - radioactive tracers are used to diagnose and treat disease

17. Effects of Exposure

18. Nuclear Decay and Stability
About 85% of nuclei are unstable
Stability depends on the neutron/proton ratio

19. Nuclear Decay and Stability
For elements with atomic numbers 20 and below, the stability is 1. (p=n)

20. Nuclear Decay and Stability
For atomic numbers above 20, stable nuclei have more n’s than p’s.( ratio ~1.5)

21. Stability Belt

22. Nuclear Decay and Stability
All nuclei with atomic number 83 and above are radioactive
These nuclei have too many n and p
They all undergo decay

23. Half-Life Every radioisotope has a rate of decay measured by half-life
It is the time required for 1/2 of the nucleus of a radioisotope to decay
Measured in units of time

24. Half-Life
After one half-life, 1/2 the original sample remains, after a second half-life, 1/4 the original remains

25. Half-Life

26. Half-Life

27. How many grams remain after 30 minutes?
Half-Life
2.00 grams of Nitrogen-13 decays via electron capture w/ a h-l of 10 min.
How many grams remain after 30 minutes?

28. Transmutation Reactions
The conversion of one atom of an element to an atom of another element when high energy particles bombard the nucleus

29. Transuranium Elements
Elements with atomic numbers above 92
undergo transmutation reactions

30. Nuclear Fission
When nuclei are bombarded with neutrons, the nucleus splits into smaller fragments
Unleashes enormous amounts of energy

31. Nuclear Fission

32. Nuclear Fission

33. Nuclear Fission
Controlled fission, where neutrons bombard Uranium-235, is used in nuclear reactors to create huge amounts of energy which is turned into steam and then electrical energy

34. Nuclear Fission

35. Nuclear Fusion
Nuclei combine to produce a nucleus of greater mass
occurs at high T and releases a lot of energy

36. Nuclear Fusion
solar fusion occurs all the time on the sun and planets

37. Extra Practice
The parent nuclide is Thorium-232. The first four decays are a, b, b, a. Write the nuclear equations for the series of emissions.

38. Extra Practice
The half-life of radium-224 is 3.66 days. What was the original mass of radium-224 if g remains after 7.32 days?