2. 1 Nuclear Chemistry

3. 2 Radioactivity One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of (1876-1934).One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934). She discovered radioactivity or radioactive decay, the spontaneous disintegration of the nuclei of some elements.She discovered radioactivity or radioactive decay, the spontaneous disintegration of the nuclei of some elements.

4. 3 Isotopes Isotopes – different numbers of NEUTRONS Some isotopes more stable than others

5. 4 Band of Stability Shows the ratios of protons to neutrons in a stable nucleus

6. 5 Radioisotopes isotopes with unstable nucleus undergo radioactive decayundergo radioactive decay Elements with atomic number 83 and up are radioactiveElements with atomic number 83 and up are radioactive Bismuth and beyond…..Bismuth and beyond…..

7. 6 Radioactivity or Radioactive Decay describes the spontaneous change(s) that radioisotopes undergo to become stable

8. 7 Radioactivity or Radioactive Decay An unstable nucleus gives off particles and/or energyAn unstable nucleus gives off particles and/or energy This changes the atomic number (p + ) and forms a new element with a more stable nucleusThis changes the atomic number (p + ) and forms a new element with a more stable nucleus Transmutation- the change in the identity of the element after it undergoes radioactive decay

9. 8 Nuclear Reactions vs. Normal Chemical Changes “Normal” Chemical Reactions involve rearranging atoms. The elements don’t change.“Normal” Chemical Reactions involve rearranging atoms. The elements don’t change. Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The nucleus opens, and protons and neutrons are rearrangedThe nucleus opens, and protons and neutrons are rearranged The opening of the nucleus releases a tremendous amount of energy that holds the nucleus togetherThe opening of the nucleus releases a tremendous amount of energy that holds the nucleus together

10. 9 Radiation The penetrating rays (energy or particles) emitted by a radioactive sourceThe penetrating rays (energy or particles) emitted by a radioactive source

11. 10 Types of Radiation Alpha Beta Gamma Positron Emission Electron Capture

12. 11 Types of Radiation Alpha (α) – a positively charged helium nucleus Alpha (α) – a positively charged helium nucleus Beta (β) – an electronBeta (β) – an electron Gamma (γ) – pure energy; called a ray rather than a particleGamma (γ) – pure energy; called a ray rather than a particle

13. 12 Other Nuclear Particles Neutron Neutron Positron – a positive electron Positron – a positive electron Proton – usually referred to as hydrogen-1Proton – usually referred to as hydrogen-1

14. 13 Penetrating Ability

15. 14 Equations Radioactive Decay is represented with an equation Protons and masses on both sides of the equation MUST balance

16. 15 Balancing Nuclear Reactions In the reactants (starting materials – on the left side of an equation) and products (final products – on the right side of an equation) Atomic numbers must balance and Mass numbers must balance Use a particle or isotope to fill in the missing protons and neutrons

17. 16 Alpha Radiation

18. 17 Nuclear Reactions Alpha emissionAlpha emission 1.Masses (top numbers) add up to 238 on both sides of arrow 2.The number of protons (bottom numbers) are both equal Note that mass number (A) goes down by 4 and atomic number (Z) goes down by 2. Nucleons (nuclear particles… protons and neutrons) are rearranged but conserved

19. 18 Nuclear Reactions Alpha emissionAlpha emission Try this one:Try this one: Po – 210 undergoes alpha radiation Po – 210 undergoes alpha radiation

20. 19 Beta Decay

21. 20 Nuclear Reactions Beta emissionBeta emission Note that mass number is unchanged and atomic number goes up by 1.

22. 21 Nuclear Reactions Beta emissionBeta emission Try this one:Try this one: Uranium – 238 undergoes beta decay Uranium – 238 undergoes beta decay

23. 22 Gamma Radiation High energy photon, usually released with alpha or beta particles What are photons? Gamma rays have very high energy, and must be shielded using lead or concrete

24. 23 Gamma Radiation

25. 24 Alpha, Beta, Gamma Charges

26. 25 Sum up the 3 main types

27. 26 Nuclear Fission

28. 27 Nuclear Fusion

29. 28 Nuclear Reaction

30. 29 Nuclear Power Plants

31. 30 SO YOU SAY YOU WANT TO MELTDOWN YOUR OWN POWER PLANT? HERE’S YOUR CHANCE TO PLAY HOMER SIMPSON.

32. 31 Nuclear Power Pros and Cons Lot’s of energy No green house gases Uses very little fuel Very small chance of massive disaster Potential target for terrorists Nuclear waste

33. 32 Accidents can happen The worst nuclear accident in US history occurred on Three Mile Island in PA 1979 The reactor meltdown was caused by several mechanical errors as well as human error creating a coolant leak The reactor that had the melt down is no longer in use. The other reactor is slated to remain in use until 2034 “London Calling” by The Clash is about this accident

34. 33 Chernobyl – April 1986 Chernobyl Nuclear Power Plant– Pripyat, Ukraine; April 1986 During a test, the reactor received a power spike, causing several explosions Radiation was picked up several hundred miles away, prompting the Soviet Union to admit the accident, 3 days after it happened

35. 34 Japan – Fukushima Power Plant March 2011

36. 35 Radiation Detection Film Badges – exposure of film measures radiation exposure Geiger Counters- detect radiation through electric pulses in ionized gas Scintillation Counters- measure radiation from substances that emit visible light when energy is absorbed

37. 36 Radiation Detection

38. 37 Uses of Radiation Radioactive dating can determine the approximate age of an object There are many uses of radiation in the medical field –Detect and kill cancerous cells –X-Rays –Many others Disinfect foods

39. 38 Personal Dose Chart

40. 39 Effects of Radiation on the Body Effects of Radiation on the Body

41. 40 Half Life Time it takes for ½ a sample to decayTime it takes for ½ a sample to decay No two radioisotopes decay at the same rateNo two radioisotopes decay at the same rate Can be as short as a few seconds or take billions of years….Can be as short as a few seconds or take billions of years….

42. 41

43. 42

44. 43 Half Life Uranium-238 has a half-life of 4.5 billion years. It’s stable ending element is lead (Pb)Uranium-238 has a half-life of 4.5 billion years. It’s stable ending element is lead (Pb)

45. 44 Half Life

46. 45 Half Life

47. 46 Half Life A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The half- life of Sr-90 is 28 years. a)How many years will it take for 0.625 grams of Sr-90 to remain? b)What year will this be?

48. 47 Half Life A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The half- life of Sr-90 is 28 years. a)How many years will it take for 0.625 grams of Sr-90 to remain? 56 years b)What year will this be? 2016

49. 48 Half Life The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain?

50. 49 Half Life The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain? 2.5 mg