Name______Date______
Modern Chemistry • CHAPTER 22
HOMEWORK N-2
(pp. 705–712)
VOCABULARY
Complete.
1. In the process of radioactive decay, a nucleus spontaneously disintegrates into ______
______.
2. Radioactive decay is accompanied by ______
______.
3. Nuclear radiation is ______.
4. A radioactive nuclide is ______
______.
Define.
1. half-life ______
2. decay series ______
______
3. parent nuclide ______
4. daughter nuclides ______
5. transuranium elements ______
GRAPHIC ORGANIZER
Complete the chart by summarizing the different types of radioactive decay. List each type of decay
and give a short explanation of what happens during each process.
Solve. Show your work!!!
______1.The half-life of iodine-131 is 8.040 days. What percentage of an iodine-131 sample will remain
after 40.2 days?
______2.Uranium-238 decays through alpha decay with a half-life of 4.46 x 109 years. How long would
it take for 7/8 of a sample of uranium-238 to decay?
______3.What percentage of argon-39 has decayed after 1.50 x 103 years? (Its half-life is 265 years.)
______4.A rock sample contained 5.0 g of In-115. The half-life of In-115 is 4.0 days. Determine the time
when only 3.0 g of In-115 remains.
______5.The half-life of a radioactive isotope is 6.0 hours. After 8 half-lives, how much of a 1.0-mg sample
will remain?
STANDARDIZED TEST PREP
Circle the letter of the best answer.
1. Which process is occurring during the reaction represented by this equation? 50
120 Sn?2
4He + 48
116 Cd
a. beta decay
b. gamma emission
c. alpha decay
d. the gaining of a positron
2. The half-life of H-3 is 12.26 years. What percentage of H-3 will remain after 0.100 centuries?
a. 27.2%
b. 0.568%
c. 56.8%
d. All of the element will have decayed.
Circle the letter of the best answer.
1 The equation 92
238 U ?2
4He + 90
234 Th represents
a. beta emission.
b. alpha emission.
c. gamma emission.
d. electron capture.
2. The equation 11
22 Na + –
1
0 e ?10
22 Ne represents
a. beta emission.
b. alpha emission.
c. gamma emission.
d. electron capture.
CHAPTER 22 • HOMEWORK 22-3
VOCABULARY
1. a slightly lighter and more stable nucleus
2. the emission of particles, electromagnetic radiation, or both
3. the radiation emitted from the nucleus during radioactive decay
4. an unstable nucleus that undergoes radioactive decay
GRAPHIC ORGANIZER
Summaries will vary. The types of decay listed should be alpha emission, beta emission, positron
emission, electron capture, and gamma emission. Explanations should include information found on
pages 706–707.
STANDARDIZED TEST PREP
1. b
2. d
VOCABULARY
1. the time required for half the atoms of a radioactive nuclide to decay
2. a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide
is reached
3. the heaviest nuclide of each decay series
4. the nuclides produced by the decay of the parent nuclides
5. the bombardment of stable nuclei with charged and uncharged particles to create artificial
radioactive nuclides
6. elements with more than 92 protons in their nuclei
SKILL BUILDER
1. 3.13%
2. 1.34 x 1010 years
3. 98.02%
4. 3.0 days
5. 0.00391 mg
STANDARDIZED TEST PREP
1. c
2. c