1. Warmup 1.What are isotopes? 2.Which particles reside in the atomic nuclei? 3.Which particle hold the nucleus together? 4.How many protons and neutrons are in: 4 2 He? 5.What is radiation?

2. Objectives I can list factors for radioactive decay. I can characterize alpha, beta and gamma radiation and write balanced nuclear equations for each. I can describe the difference between fission and fusion

4. Nuclear reaction – reactions in which the nuclei of unstable isotopes gain stability by undergoing a change that is accompanied by a large amount of energy Radioisotope: an isotope that has an unstable nucleus. It is radioactive. Radioisotope nucleus

5. Radiation is the energy that is released by a nuclear change. Radioactive Decay is the emission of radiation by an unstable nucleus.

6. What makes a nucleus unstable? Remember that neutrons hold the nucleus together. The nucleus of an element becomes unstable if there are not enough neutrons or if there are too many neutrons. A stable nucleus depends on the proportion of neutrons to protons in the nucleus. http://phet.colorado.edu/en/simulation/build-an-atomhttp://phet.colorado.edu/en/simulation/build-an-atom do boron

7. A stable nucleus depends on the proportion of neutrons to protons in the nucleus. + + + + +

8. Stable Isotope Unstable: Radioactive Isotope Band of Stability

9. [Default] [MC Any] [MC All] Stable Isotope Unstable: Radioactive Isotope An isotope of neon has 10 protons and 14 neutrons. Is this isotope likely to be A. stable B. a radioisotope

10. [Default] [MC Any] [MC All] Stable Isotope Unstable: Radioactive Isotope Is an atom of the isotope 90 39 Y likely to be A. stable B. unstable

11. [Default] [MC Any] [MC All] Stable Isotope Unstable: Radioactive Isotope The element protactinium has 91 protons. Could stable isotopes exist? A.Yes with about 64 neutrons B.Yes with about 140 neutrons C.No the nucleus is too big

12. ALPHA, BETA, GAMMA There are three types of radiation produced by nuclear decay that we will study…….

13. In alpha radiation, a radioactive source emits an alpha particle which consists of 2 protons and 2 neutrons. An alpha particle is simply a helium atoms’ nucleus simulation of radium decay alpha particle

14. The symbol of an alpha particle is 4 2 He The mass of an alpha particle is 4 amu The charge of an alpha particle is +2 Example of alpha radiation: Radon - 222Polonium - 218 α

15. The symbol of an alpha particle is 4 2 He The mass of an alpha particle is 4 amu The charge of an alpha particle is +2 Example of alpha radiation: simulation of radium decay Radon - 222Polonium - 218 α  +

16. Alpha particles are large and have a charge. They do not travel far and are not very penetrating. They can be stopped by a sheet of paper, clothing, or skin. However, they can penetrate soft tissue.

17. [Default] [MC Any] [MC All] A scientist observes a radioisotope emit an alpha particle and become a stable isotope. The new isotope’s ___________ A.atomic number is 4 less B.atomic number is 2 less C.mass number is 4 less D.mass number is 2 less

18. 2. Beta radiation A radioactive source emits a beta particle = a fast-moving electron formed by the decomposition of a neutron in an atom. The neutron decomposes to form a proton and an electron. Only the electron is emitted. beta particle

19. The symbol of a beta particle is 0 -1 e The mass of a beta particle is 1/1840 amu The charge of a beta particle is -1

20. Balance nuclear equation of beta radiation 14 6 C  Carbon-14

21. Balance nuclear equation of beta radiation 14 6 C  0 -1 e + 14 7 N Carbon-14 BetaNitrogen-14 Particle Simulation of Carbon-14 Beta decay

22. Beta particles have a small mass so they are more penetrating. These can be stopped by aluminum foil or thin pieces of wood.

23. Beta Radiation is used in the paper making industry to automatically measure and control the thickness.

24. A scientist observes an unstable nucleus emit a beta particle. Afterwards the nucleus….. A.atomic number increases by one B.atomic number decreases by one C.gains one mass number D.mass stays the same

25. 3. Gamma radiation A radioactive source emits a high-energy electromagnetic radiation – gamma rays. Gamma rays are usually released along with alpha or beta radiation The symbol of gamma radiation is γ

26. Gamma radiation does not have a charge or a mass 230 90 Th  226 88 Ra + 4 2 He + γ Thorium-230 Radium-226 Alpha Gamma Particle Ray

27. Gamma rays (similar to x- rays) can easily penetrate wood or human skin. It can be stopped by several meters of concrete or by several centimeters of lead. gamma ray

28. Cancerous cell are killed by high doses of gamma. A number of sources of gamma are focused on the cancerous cells so that most of the dose is absorbed. The surrounding healthy cells receive a lower dose.

30. In order from most to least penetrating nuclear radiation. A.alpha, beta, gamma B.alpha, gamma, beta C.gamma, beta, alpha D.gamma, alpha, beta

31. Half-Life The amount of time required for one-half of the nuclei of a radioisotope to decay to its products After one half-life, only half of the original amount of sample will remain. Every radioisotope has a unique half-life 13.859 second Half Life Simulation http://phet.colorado.edu/en/simulation/alpha-decay

32. What is the half life of this radioisotope? 80 40 20 10 5 2.5

33. 5.0 0.1 What is the half life of this radioisotope? 80 40 20 10 5 2.5 _____days

34. Half-lives may be fractions of a second or billions of years long. Uses include: Carbon-14 dating, and use in nuclear medicine

35. simulations Simulation of Carbon-14 Beta decay 13.859 second Half Life Simulation simulation of radium alpha decay

36. The following equation can be used to find the remaining amount after a certain number of half-lives have passed: N = N 0 (½) n or N = N 0 (½) t/T N is the remaining amount N 0 is the initial amount n is the number of half-lives that have passed t is the elapsed time and T is the duration of the half- life

37. A 20.0 g sample of Nitrogen-13 undergoes beta radiation and has a half-life of 15 min. a) How much Nitrogen-13 will be left after 15 min?

38. A 20.0 g sample of Nitrogen-13 undergoes beta radiation and has a half-life of 15 min. a) How much Nitrogen-13 will be left after 30 min?

39. A 20.0 g sample of Nitrogen-13 undergoes beta radiation and has a half-life of 15 min. a) How much Nitrogen-13 will be left after 45 min?

40. Example 2 A patient is administered 20mg of radioactive iodine-131. How much of this radioisotope will remain in the body after 32 days if the half-life of iodine-131 is 8 days?

41. NUCLEAR TRANSFORMATIONS Ch 24

42. review nuclear decay organizer

43. Greek letter MassCharge Particle Symbol Particle emitted paper or skin thin wood or metal foil lead or concrete 1. Alpha Radiation 2. Beta Radiation 3. Gamma Radiation Alpha Decay Example: Americium-241 241 95 Am  Beta Decay Example: Cesium-137 137 55 Cs  Gamma Decay Example: 60 27 Co  as part of beta decay of cobalt-60 Nuclear Decay and Radiation Facts

44. Greek letter MassCharge Particle Symbol Particle emitted paper or skin thin wood or metal foil lead or concrete 1. Alpha Radiation α 4 amu ( 2 neutrons 2 protons) +2 4 2 He 2. Beta Radiation  1/1840 amu (fast electron) 0 -1 e 3. Gamma Radiation  0 amu (ray of energy) 0  Nuclear Decay and Radiation Facts Alpha Decay Example: Americium-241 241 95 Am  4 2 He + 237 93 Np Beta Decay Example: Cesium-137 137 55 Cs  0 -1 e + 137 56 Ba Gamma Decay Example: 60 27 Co  0 -1 e + 60 28 Ni +  as part of beta decay of cobalt-60

45. The splitting of a nucleus into smaller fragments. When a nucleus is bombarded by a neutron, it breaks into two smaller nuclei and releases more neutrons (domino effect)

46. Releases huge amounts of energy. 1 kg of uranium-235 will release enough energy to equal the explosion of 20,000 tons of dynamite. This is what nuclear bombs make use of. U-235 neutron energy Uncontrolled Uranium Chain Reaction Simulation PHeT fission simulation

47. Nuclei fuse together to form a nucleus of greater mass—releasing a huge amount of energy. This is the process by which the sun produces its energy

48. Fusion fuels are inexpensive and do not produce radioactive products Fusion requires extremely high temperatures and would destroy any container it’s held in. Research Fusion Reactor Core – magnetic field containment

49. Americium 241 half life = 432.2 years