Exercises 39.1 The Atomic Nucleus (pages 783 784) 1.Circle the letter of each nucleon. a. proton b. neutron c. electron d. positron 2. Is the following sentence true or false? The mass of a proton and an electron are nearly the same. 3. Most of an atom s mass is located in its. 4. Describe the relationship between the number of protons and the number of electrons in a neutral atom. 5. Circle the letter of the particle that determines the kind of element and the chemical properties of an atom. a. proton b. neutron c. electron d. positron 6. Describe the primary role of the neutrons in the nucleus of an atom. 7. Circle the letter that best describes the strong force. a. an attractive magnetic force b. a repulsive electric force c. an attractive nuclear force d. an attractive gravitational force 8. Is the following sentence true or false? The strong force acts across large distances. 9. The two major forces that act on a nucleus are the strong force and. 10. A nucleus needs a certain ratio of to to make it stable. 39.2 Radioactive Decay (pages 785 786) 11. What will a lone neutron decay into? 12. Particles that decay spontaneously and emit particles and energy are said to be. 13. Explain what is meant by saying that radioactivity is governed by massenergy equivalence. 14. All atoms with atomic numbers greater than decay in one way or another. Conceptual Physics Reading and Study Workbook 337
15. Circle the letter of the name given to the charged particles and energy emitted by an unstable nucleus. a. radiation b. Planck emission c. transmutation d. transuranium 16. Circle the letter of the type of radiation that has a positive charge. a. alpha particle b. gamma ray c. neutrino d. beta particle 17. Is the following sentence true or false? Gamma rays have no charge. 18. The types of radiation that are deflected by a magnetic field are and. 19. Is the following sentence true or false? An alpha particle is identical to a helium nucleus. 20. A(n) is ejected from a nucleus when a neutron is converted into a proton. 21. Is the following sentence true or false? Gamma rays have zero mass. 22. Compare and contrast gamma rays and visible light rays. How are they similar? How are they different? 39.3 Radiation Penetrating Power (pages 786 787) 23. Is the following sentence true or false? Alpha, beta, and gamma radiation have roughly equal abilities to penetrate matter. 24. Radiation with a large and a small will have the greatest penetrating ability. 25. Based on the figure to the right, circle the letter that correctly ranks the types of radiation from least penetrating to most penetrating. a. alpha particles, gamma rays, beta particles b. gamma rays, beta particles, alpha particles c. alpha particles, beta particles, gamma rays d. gamma rays, alpha particles, beta particles 338 Conceptual Physics Reading and Study Workbook
26. Is the following sentence true or false? Gamma rays are not stopped unless they directly strike a metal surface. 39.4 Radioactive Isotopes (pages 788 789) 27. Circle the letter that best describes isotopes of an element. a. same composition and chemical properties b. differing composition and identical chemical properties c. differing composition and differing chemical properties d. same composition and physical properties 28. The atomic number of an atom is the number of in the nucleus. 29. The atomic mass number of an atom is the total number of in the nucleus. 30. In isotope notation form, the 2 in 1 2 Histhe and the 1 is the. 31. Is the following sentence true or false? All isotopes are radioactive. 39.5 Radioactive Half-Life (pages 790 791) 32. Is the following sentence true or false? All radioactive nuclei decay at the same constant rate. 33. Define half-life. Use the following graph to answer Questions 34 and 35. Rate of Decay of Radium 34. The boxes in the graph above represent how much of a sample of radium has decayed over time. What is the half-life of radium? 35. Insert the missing masses on the lines next to the vertical axis of the graph. 36. The of a particular radioisotope is constant and not affected by external conditions. Conceptual Physics Reading and Study Workbook 339
39.6 Natural Transmutation of Elements (pages 792 794) 37. What is transmutation? 38. Circle the letter that describes how an atom changes when it undergoes alpha decay. a. its atomic number increases by 2 b. its atomic number decreases by 2 c. its mass number increases by 2 d. its mass number increases by 4 39. Circle the letter that describes how an atom changes when it undergoes beta decay. a. its mass number increases by 1 b. its atomic number increases by 1 c. its mass number decreases by 1 d. its mass number increases by 4 40. Is the following sentence true or false? Beta emission has almost no effect on the mass of the nucleus. 41. Is the following sentence true or false? Radioactive nuclei always decay down the periodic table, in the direction of decreased mass. 39.7 Artificial Transmutation of Elements (page 795) 42. Is the following sentence true or false? Transmutation can be forced to occur in laboratory. 43. Who was the first person to transmute an element artificially? 44. What is significant about all of the elements beyond uranium on the periodic table? 39.8 Carbon Dating (pages 796 797) 45. Most of the carbon on Earth exists in the form of. 46. Is the following sentence true or false? All living things contain both carbon-12 and carbon-14. 47. How is the ratio of carbon-14 to carbon-12 in a living organism related to the ratio of carbon-14 to carbon-12 in the atmosphere? 340 Conceptual Physics Reading and Study Workbook
48. How do scientists figure out how long ago a plant or animal died using carbon dating? 49. Is the following sentence true or false? Archeologists use carbon dating techniques on skeletons. 39.9 Uranium Dating (page 798) 50. What is uranium dating? 51. How is the percentage of lead isotopes in an ancient uranium-bearing rock related to its age? 52. Circle the letter of the age of the oldest rocks on Earth that have been dated using uranium dating. a. 1.2 million years b. 2.2 million years c. 4.2 billion years d. 12.2 billion years 39.10 Radioactive Tracers (pages 798 799) 53. Describe what a tracer is. 54. Describe two uses of radioactive tracers. 39.11 Radiation and You (pages 800 801) 55. What are three sources of natural background radiation? 56. Is the following sentence true or false? Cosmic radiation is more intense at lower elevations than at higher elevations. 57. Our bodies are bombarded most by massless chargeless particles called. 58. Circle the letter of the most damaging form of radiation. a. alpha particles b. gamma rays c. beta particles d. positrons 59. Is the following sentence true or false? People who receive high doses of radiation have shorter life expectancies than those who do not. Conceptual Physics Reading and Study Workbook 341