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Physical Science Chapter 7

Short Answer

1. What are massive, positively charged particles emitted by some radioactive elements?

2. What is the energy and matter released by radon gas that causes health concerns called?

3. If the atomic number of an atom before alpha decay is 88, and one of its products has an atomic number of 86, what is the atomic number of the second product?

4. Who was the scientist who showed that alpha particles are helium nuclei?

88226 Ra → 86

222 Rn + 24 He

5. In this example, the helium is also known as what?

6. What type of particle is emitted when carbon-14 decays into nitrogen-14?

7. What is the time required for half a sample of radioactive nuclei to decay called?

8. After three half-lives, what fraction of the original radioactive element remains?

9. To determine the age of fairly recent remains (in the tens of thousands of years as opposed to millions of years), scientists compare the ratio of what two elements?

10. Potassium-40 decays into argon-40. Geologists use a technique to calculate the age of very old rocks by comparing the ratio of the amount of potassium-40 to argon-40. What is the technique?

11. A nucleus depends on the nuclear forces acting between the protons and the neutrons, which hold the nucleus together, to provide what?

12. What is the force that binds protons and neutrons together in a nucleus called?

13. The protons in a nucleus both repel and attract each other. In stable nuclei, which are stronger, the attractions or the repulsions?

14. Name the interaction that binds protons and neutrons together in a nucleus.

15. The equivalence of mass and energy means that matter can be converted into energy and energy into matter. Write the equation that expresses this equivalence.

16. What is the process by which a nucleus splits into two or more smaller fragments, releasing neutrons and energy, called?

17. What is the name for the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy?

18. What is one example of a place where naturally occurring extreme temperatures provide the energy needed to bring hydrogen nuclei together in a fusion reaction?

19. According to the theory of relativity, what does mass times the speed of light squared equal?

20. Who was the scientist who first presented the theory of relativity?

21. In the equation, E = mc2, what does the E stand for?

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22. In the equation, E = mc2, what does the m stand for?

23. In the equation, E=mc2, what does c stand for?

24. Name one good use of the energy produced in a controlled chain reaction.

25. What is nuclear radiation that is emitted from natural sources all around us called?

26. Ionization occurs when atoms lose or gain what?

27. Leucopenia, hair loss, sterility, bone necrosis, and cancer are all common symptoms of what sickness?

28. Birth defects can occur when exposure to radiation causes damage to what part of reproductive cells?

29. What is a short-lived isotope called that a geologist might use to follow underground water flow through an area?

30. Which is capable of producing the most energy, the known uranium reserves or the known reserves of coal and oil combined?

31. The main problem with disposing of radioactive wastes is that they have a long what?

32. What is the most likely fuel for nuclear-fusion reactors?

33. In nuclear-fission reactors operating today, what is the most common fuel?

34. What type of nuclear radiation can travel farthest through matter and why?

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Physical Science Chapter 7Answer Section

SHORT ANSWER

1. alpha particles, helium nuclei 2. nuclear radiation 3. 2 4. Ernest Rutherford 5. the alpha particle 6. a beta particle 7. the half-life 8. one-eighth 9. carbon-14 and carbon-12 10. radioactive decay rate / half-life 11. stability 12. strong nuclear force 13. the attractions 14. a strong nuclear force 15. E = mc2

16. fission 17. fusion 18. stars 19. energy 20. Albert Einstein 21. energy 22. mass 23. the speed of light 24. generating electricity 25. background radiation 26. electrons 27. radiation sickness 28. DNA 29. a radioactive tracer 30. the known uranium reserves 31. half-life 32. hydrogen 33. uranium-235 34. Gamma rays