1. 1 Nuclear Radiation Natural Radioactivity Nuclear Equations Producing Radioactive Isotopes Half-Life Nuclear Fission and Fusion Photoelectric effect Duality of Light

2. 2 Subatomic Particles Protons- plus charge In the nucleus Neutrons- neutral Electrons - negative charge Outside the nucleus

3. 3 Radiation Radiation comes from the nucleus of an atom. Unstable nucleus emits a particle or energy  alpha  beta  gamma

4. 4 Alpha Particle Same as a helium nucleus (He) 4 2 He or  Two protons Two neutrons

5. 5 Beta Particle  An electron emitted from the nucleus 0 e or   1 A neutron in the nucleus breaks down 11 0 n H +e 0 1 -1

6. 6 Gamma  Radiation Pure radiation Like an X-ray but comes from the nucleus

7. 7 Radiation Protection Shielding alpha – paper, clothing beta – lab coat, gloves gamma- lead, thick concrete Limit time exposed Keep distance from source

8. 8 Radiation Protection

9. 9 Balancing Nuclear Equations In the reactants and products Atomic numbers must balance and Mass numbers must balance

10. 10 Alpha decay

11. 11 Beta decay 234 Th  234 Pa + 0 e 90 91  1 beta particle

12. 12 Gamma radiation No change in atomic or mass number 11 B 11 B + 0  5 5 0 boron atom in a high-energy state

13. 13 Learning Check NR1 Write the nuclear equation for the beta emitter Co-60.

14. 14 Solution NR1 Write the nuclear equation for the Beta emitter Co-60. 60 Co 60 Ni + 0 e 27 28 -1

15. 15 Producing Radioactive Isotopes Bombardment of atoms produces radioisotopes = 60 = 60 59 Co + 1 n 56 Mn + 4 H e 27 0 25 2 = 27= 27 cobalt neutron manganese alpha atom radioisotope particle

16. 16 Learning Check NR2 What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He ? + 1 n 5 2 0

17. 17 Solution NR2 What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He 13 N + 1 n 5 2 7 0 nitrogen radioisotope

18. 18 Half-Life of a Radioisotope The time for the radiation level to fall (decay) to one-half its initial value decay curve 8 mg 4 mg2 mg 1 mg initial 1 half-life 2 3

19. 19 Examples of Half-Life Isotope Half life C-152.4 sec Ra-2243.6 days Ra-22312 days I-12560 days C-145700 years U-235710 000 000 years

20. 20 Learning Check NR3 The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours?

21. 21 Solution NR3 t 1/2 =13 hrs 26 hours = 2 x t 1/2 Amount initial =64mg Amount remaining = 64 mg x ½ x ½ = 16 mg

22. 22 Nuclear Fission Fission large nuclei break up 235 U + 1 n 139 Ba + 94 Kr + 3 1 n + 92 0 56 36 0 Energy

23. 23 Fission

24. 24 Nuclear Fusion Fusion small nuclei combine 2 H + 3 H 4 He + 1 n + 1 1 2 0 Occurs in the sun and other stars Energy

25. 25 Learning Check NR4 Indicate if each of the following are (1)Fission(2) fusion A.Nucleus splits B.Large amounts of energy released C.Small nuclei form larger nuclei D.Hydrogen nuclei react Energy

26. 26 Solution NR4 Indicate if each of the following are (1)Fission(2) fusion A. 1 Nucleus splits B. 1 + 2 Large amounts of energy released C. 2 Small nuclei form larger nuclei D. 2 Hydrogen nuclei react

27. Photoelectric Effect The photoelectric effect occurs when light incident on certain metallic surfaces causes electrons to be emitted from those surfaces –The emitted electrons are called photoelectrons

28. Photoelectric Effect Apparatus When the tube is kept in the dark, the ammeter reads zero When plate E is illuminated by light having an appropriate wavelength, a current is detected by the ammeter The current arises from photoelectrons emitted from the negative plate and collected at the positive plate

29. Photoelectric Effect In the photoelectric effect, it was observed that shining a light on certain metals would lead to an electric current in a circuit. Presumably, the light was knocking electrons out of the metal, causing current to flow. 29

30. Duality of Light Wave–particle duality postulates that all particles exhibit both wave and particle properties. Morgan Freeman Explains in his wonderful voiceMorgan Freeman Explains in his wonderful voice 30