1. THE NUCLEUS: A CHEMIST’S VIEW
Chapter Eighteen:
THE NUCLEUS: A CHEMIST’S VIEW

2. Review Atomic Number (Z) – number of protons
Mass Number (A) – sum of protons and neutrons
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

3. Radioactive Decay
Nucleus undergoes decomposition to form a different nucleus.
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

4. Radioactive Stability
Nuclides with 84 or more protons are unstable.
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

5. Radioactive Stability
Light nuclides are stable when Z equals A – Z (neutron/proton ratio is 1).
For heavier elements the neutron/proton ratio required for stability is greater than 1 and increases with Z.
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

6. Radioactive Stability
Certain combinations of protons and neutrons seem to confer special stability.
Even numbers of protons and neutrons are more often stable than those with odd numbers.
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

7. Radioactive Stability
Certain specific numbers of protons or neutrons produce especially stable nuclides.
2, 8, 20, 28, 50, 82, and 126
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 6

8. The Zone of Stability
Copyright © Houghton Mifflin Company. All rights reserved.

9. Types of Radioactive Decay
Alpha production ():
Beta production ():
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 1

10. Types of Radioactive Decay
Gamma ray production ():
Positron production:
Electron capture:
18.1
Copyright © Houghton Mifflin Company. All rights reserved. 2

11. Decay Series (Series of Alpha and Beta Decays)
Copyright © Houghton Mifflin Company. All rights reserved.

12. Nuclear Particles
18.2
Copyright © Houghton Mifflin Company. All rights reserved.

13. Nuclear Transformation
The change of one element into another.
18.3
Copyright © Houghton Mifflin Company. All rights reserved. 6

14. A Schematic Diagram of a Cyclotron
18.3
Copyright © Houghton Mifflin Company. All rights reserved.

15. A Schematic Diagram of a Linear Accelerator
Odd-numbered tubes are negatively charged, and the even-numbered tubes are positively charged.
18.3
Copyright © Houghton Mifflin Company. All rights reserved.

16. Measuring Radioactivity Levels
Geiger counter
Scintillation counter
18.4
Copyright © Houghton Mifflin Company. All rights reserved. 6

17. Geiger Counter
18.4
Copyright © Houghton Mifflin Company. All rights reserved.

18. Energy and Mass
When a system gains or loses energy it also gains or loses a quantity of mass.
E = mc2
m = mass defect
E = change in energy
If E is negative (exothermic), mass is lost from the system.
18.5
Copyright © Houghton Mifflin Company. All rights reserved. 7

19. Binding Energy
The energy required to decompose the nucleus into its components.
Iron-56 is the most stable nucleus and has a binding energy of 8.97 MeV.
18.5
Copyright © Houghton Mifflin Company. All rights reserved. 8

20. Binding Energy per Nucleon vs. Mass Number
18.5
Copyright © Houghton Mifflin Company. All rights reserved.

21. 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.
18.6
Copyright © Houghton Mifflin Company. All rights reserved. 9

22. Nuclear Fission
18.6
Copyright © Houghton Mifflin Company. All rights reserved.

23. Fission Processes
A self-sustaining fission process is called a chain reaction.
18.6
Copyright © Houghton Mifflin Company. All rights reserved. 10

24. Schematic Diagram of a Nuclear Power Plant
18.6
Copyright © Houghton Mifflin Company. All rights reserved.

25. Schematic Diagram of a Reactor Core
Copyright © Houghton Mifflin Company. All rights reserved.

26. Nuclear Fusion
18.6
Copyright © Houghton Mifflin Company. All rights reserved.

27. Biological Effects of Radiation
Depend on:
Energy of the radiation
Penetrating ability of the radiation
Ionizing ability of the radiation
Chemical properties of the radiation source
18.7
Copyright © Houghton Mifflin Company. All rights reserved. 13

28. Effects of Short-Term Exposures on Radiation
18.7
Copyright © Houghton Mifflin Company. All rights reserved.