Chemistry I
Radiation/Half-LifeWorksheet
Answer the following questions with the best possible answer…
1. Which form of radiation has the most penetrating power? ______________________________________
2. Which form of radiation is the same as an electron? ___________________________________________
3. Which form of radiation is the same as a Helium nucleus? ______________________________________
4. Which form of radiation changes a neutron into a proton by removing an electron? ___________________
5. Which form of radiation is the largest and most damaging? _____________________________________
5. Some isotopes, after undergoing alpha or beta decay, have nuclei that are in an energized state. As a result,
they emit gamma radiation. These nuclei are said to be ________________________.
6. What type of radiation is shown here?
14
14
C
N + 0e
6
7
-1
7. What type of radiation is shown here?
228M
228
Ra
Ra + energy
8. What type of radiation is shown here?
234Th + 4 He
238 U
2
90
92
For the following equations, fill in the missing particle or atom…
42
9.
0
e
-1
K
10.
239
11.
235
92 U
Pu
+ __________
4
2
He + _________
231
90 Th
+ _________
12. _________
230
Ra
88
13. _________
4
2
He +
+
0
e
-1
161
65 Tb
14. Uranium (U) undergoes beta decay three times and then alpha decay once. The element created is ______.
15. Thorium (Th) undergoes alpha decay once, then beta decay four times, then alpha decay again once, and
finally, gamma once. The final element created is _____________.
16. A half-life measures the rate of _______________ of radioisotopes.
17. True or False
All elements decay at the same rate.
17. After three half lives, 62.5 grams of a radioactive isotope remain. How many grams were in the original
sample of this radioactive isotope?
18. Suppose you have a 1000.000 gram sample of element “X”. If the half life of element “X” is two years:
a. How many half-lives would it take for your sample to decay to 15.625 grams of element “X”?
b. How many years would it take for your sample to decay to 15.625 grams of element “X”?
19. Suppose you have a sample containing 800 nuclei of a radioactive isotope. After one hour, only 50 of the
original nuclei remain. What is the half-life of this isotope?
20. How much of a 100.00 gram sample of 198Au is left after 8.10 days if its half-life is 2.70 days?
21. A 50.00 gram sample of 16N decays to 12.50 grams in 14.4 seconds. What is its half-life?
22. The half-life of 42K is 12.4 hours. How much of a 750.00 gram sample is left after 62 hours?
23. What is the half-life of 99Tc if a 500.00 gram sample decays to 31.25 grams in 852,000 years?
24. What was the original mass of a sample of radioactive nuclei if there are 500.00 grams of the original
sample left after 2000 years? The half-life for these radioactive nuclei is 400 years.
25. The half-life of 232Th is 1.4 x 1010 years, if there are 25.00 grams of the sample left after 2.8 x 1010 years,
how many grams were in the original sample?
26. The half-life of 222Ra is 3.28 days. How many days will it take a 900.00 gram sample of 222Ra to decay to
56.25 grams?