Review for Unit 4 The Nucleus Test
I. Vocabulary
Mass number
Atomic mass
Proton
Neutron
Electron
Isotope
Alpha radiation
Beta radiation
Gamma radiation
Half-life
Fusion
Fission
Cathode ray experiment
Plum pudding experiment
Gold foil experiment
Planetary model
Quantum mechanical model
II. Equations
Weighted average for atomic mass
Mass number
Two equations for half-life
Name ______________________________ Date ____________________
III. Sample Problems
1) List the five models of the atom below with the picture of the model, name of the scientist, and name of the
model.
Model 1:
Model 2:
Model 3:
Model 4:
Model 5:
Scientist 1:
Scientist 2:
Scientist 3:
Scientist 4:
Scientist 5:
a. Why did we change from model 1 to model 2?
b. Why did we change from model 2 to model 3?
c. Why did we change from model 3 to model 4?
d. Why did we change from model 4 to model 5?
2) Fill in the table below
Name of
Greek Letter
Radiation
Symbol in
Isotopic
Notation
Blocked by
3) Fill in the missing blanks in the nuclear equations below (use low, medium, and high for danger level)
a.
239
94Pu
b.
42
19K
c.
60
27Co
0
0
d.
235
92U
________ + 231
90Th
4
2He +
0
-1e
_________
type of radiation _______________
Danger level ____________
+ _________
type of radiation _______________
Danger level ____________
+ __________
type of radiation _______________
Danger level ____________
type of radiation _______________
Danger level ____________
4) Fill in the table with the missing information about each isotope.
Symbol% abundance Mass of atom
# protons
# electrons
mass#
K-39
93.26%
38.96amu
K-40
0.01%
39.96amu
6.73%
40.96amu
19
# neutrons
Nuclear
symbol
22
5) What is the atomic mass of potassium when calculated using the information above?
6) Compare and contrast nuclear fusion and nuclear fission. Include the sources, processes, advantages,
disadvantages, etc.
7) The half-life of gold-198 is 2.69 days. How long does it take 180 g of gold-198 to decay to 1/8 of its original
mass?
8) What percent of a sample of As-81 remains un-decayed after 43.2 seconds? The half-life of As-81 is 33 seconds.
9) What is the half-life of a radioactive isotope if 500.0 g of a sample decays to 62.5 g in 24.3 hours?
10) An isotope of cesium has a half-life of 30 years. If 1.0 g of cesium-137 disintegrates over a 90-year period, how
many grams of cesium-137 would remain?
11) The half-life of chromium-51 is 28 days. If the sample contained 510 grams, how much chromium would
remain after 56 days? How much would remain after 1 year?
12) If 20.0 g of a radioactive isotope are present at 1:00 PM and 5.0 g remain at 2:00 PM, what is the half-life of
the isotope?
13) Actinium-226 has a half-life of 29 hours. If 100 mg of actinium-226 disintegrates over a period of 58 hours,
how many mg of actinium-226 will remain?
14) The half-life of Po-218 is three minutes. How much of a 2.0 gram sample remains after 15 minutes? (Second
part is a challenge!) Suppose you wanted to buy some of this isotope, and it required half an hour for it to
reach you. How much should you order if you need to use 0.10 gram of this material?