Download Name___________________________ Chemistry, period

HONORS
Name ________________________
Mrs. Murray
Chemistry, period___
Date_____________
Unit 3: Nuclear Chemistry
Textbook: Chapter 24, pages 858-889
A. Radioactivity
1. Compare and contrast different forms of radiation.
ALPHA
BETA
RADIATION
GAMMA
POSITRON
1
HONORS
2. Write the nuclear decay equation for the following radioisotopes:
Au -198:
Fr-220:
P-32:
K-37:
Ne-19:
Sr-90
H-3
C-14:
U-238:
3. Which decay mode will attract to the negative plate in a magnetic field? __________
4. Which decay mode is positively charged? ___________________
5. Which form of radiation is neutral? __________________
6. Which is the most harmful form of radiation? _______________
7. Which decay mode will pass through a magnetic field undeflected? _______________
8. Which elements have all unstable isotopes? __________________
2
HONORS
B. Half-Life
1. How much of a 100 gram sample of Iodine-131 would be left after 24 days?
2. How long would it take for a 50 gram sample of Cesium -137 to decay to 12.5 grams?
3. What fractional amount of Cobalt-60 would remain after 10 years? After 20 years?
4. A sample of a radioactive isotope with an original mass of 8 grams is observed for 30 days.
After that time 0.25 grams of the isotope remains. What is the half life of this isotope?
5. The half life of K-42 is 12.4 hours. How much of a 750 gram sample is left after 62 hours?
6. How much of a 100 gram sample of Au-198 is left after 8.10 days if it’s half life is 2.70 days?
3
HONORS
7. A 50 gram sample of N-16 decays to 12.5 grams in 14.4 seconds. What is it’s half life?
8. A radioisotope’s half-life is 3.2 minutes. Given an initial 12 gram mass of this sample use
this information you have to draw a graph of mass of radioisotope left versus time.
Label each axes. Draw a smooth curve for the half life of this chemical. Referring to the
graph, estimate the grams of the radioisotope left after 1.5 minutes. Estimate the amount of
time that must pass in order for 1 gram of the sample.
9. What happens to the half life of a radioactive isotope if:
 heat is added ____________
 pressure is increased ___________
 a catalyst is added ______________
4
HONORS
C. Transmutation
Identify each nuclear equation as natural or induced transmutation. Predict the missing
chemicals.
D. Nuclear Energy
1. Is it possible to live radiation free?
2. What is fission? What material can be fissioned? Write a fission reaction.
3. What is the problem with nuclear energy?
4. What is fusion? What material can undergo fusion? Write a fusion reaction.
5
HONORS
E. Uses of Radioactivity
____1. Radioisotopes used for medical diagnosis must have
1.
2.
3.
4.
long half-lives and be quickly eliminated by the body
long half-lives and be slowly eliminated by the body
short half-lives and be quickly eliminated by the body
short half-lives and be slowly eliminated by the body
____2. Which radioactive isotope is used in geological dating?
1. uranium-238
2. iodine-131
3. cobalt-60
4. technetium-99
____3. Which radioactive isotope is used for the diagnosis of thyroid disease?
1. iodine-131
2. potassium-42
3. carbon-14
4. cobalt-60
____4. Base your answer to the question on the information below.
Some radioisotopes used as tracers make it possible for doctors to see the images of internal
body parts and observe their functions. The table below lists information about three
radioisotopes and the body part each radioisotope is used to study.
Which equation correctly shows the nuclear decay of the radioisotope used to study red blood
cells?
1.
24Na
→
+ 20F
3.
131I
→
2.
59Fe
→
+ 55Cr
4.
59Fe
→
+ 131Te
+ 59Co
____5. According to Table N, which radioactive isotope is best for determining the actual age of
Earth?
1.
238U
3.
60Co
2.
90Sr
4.
14C
6
HONORS
F. Regents Questions
Base your answers to questions 1 through 3 on the information below, the Reference Tables for
Physical Setting/Chemistry, and your knowledge of chemistry.
Radioactivity and radioactive isotopes have the potential for both benefiting and harming living
organisms. One use of radioactive isotopes is in radiation therapy as a treatment for cancer.
Cesium-137 is sometimes used in radiation therapy. A sample of cesium-137 was left in an
abandoned clinic in Brazil in 1987. Cesium-137 gives off a blue glow because of its radioactivity.
The people who discovered the sample were attracted by the blue glow and had no idea of any
danger. Hundreds of people were treated for overexposure to radiation, and four people died.
1. Using Reference Table N, complete the equation provided in your answer booklet for
the radioactive decay of Cs-137. Include both atomic number and mass number for each
particle.
2. If 12.5 grams of the original sample of cesium-137 remained after 90.69 years, what was
the mass of the original sample?
3. Suppose a 40-gram sample of iodine-131 and a 40-gram sample of cesium-137 were
both abandoned in the clinic in 1987. Explain why the sample of iodine-131 would not
pose as great a radiation risk to people today as the sample of cesium-137 would.
Base your answers to questions 4 through 7 on the information below, which relates the
numbers of neutrons and protons for specific nuclides of C, N, Ne, and S.
4. Using the
on the graph for
point plotted
neon,
7
HONORS
complete the table.
5. Explain, in terms of atomic particles, why S-32 is a stable nuclide.
6. Using the point plotted on the graph for nitrogen, what is the neutron-to-proton ratio
of this nuclide?
7. Based on Reference Table N, complete the decay equation for N-16 in your answer
booklet.
Base your answers to questions 8 through 10on the information below.
The radioisotopes carbon-14 and nitrogen-16 are present in a living organism.
Carbon-14 is commonly used to date a once-living organism.
8. Complete the nuclear equation for the decay of C-14. Include both the atomic number and
the mass number of the missing particle.
9. Explain why N-16 is a poor choice for radioactive dating of a bone.
10. A sample of wood is found to contain as much C-14 as is present in the wood of a
living tree. What is the approximate age, in years, of this sample of wood?
8
HONORS
G: SAT II Practice
1.
2.
3.
4.
Statement 1
Alpha particles are the
heaviest form of radiation
because
An emissions of a beta
particle results in a
decrease of the atomic
number
The most penetrating
nuclear radiation is  rays
Both nuclear fusion and
fission release energy
because
because
because
Statement 2
Alpha emission particles
consist of 2 protons and 2
neutrons
A beta particle is an electron
emitted from the nucleus.
 rays are the highest mass
radioactive particles.
Fusion and fission have been
harnessed into producing a
source of domestic energy.
1.
2.
3.
4.
9
HONORS
Unit 13 Nuclear Chemistry:
1. Elements with atomic number greater than lead (82) are naturally radioactive.
2. Transmutation is the decay of the nucleus of an atom, becoming a nucleus of a totally
different atom. Refer to TABLE N for decay modes.
3. There are three types of radiation: (TABLE O)
RADIATION
DESCRIPTION
ALPHA
helium nucleus
BETA
electron
POSITRON
+ charged
electron
high energy
radiation
CHEMICAL
SYMBOL
CHARGE
4
positively charged
2
-1
GAMMA
He
negatively charged
0
e
Positively charged
0
-1 e
zero charge

4. A nuclear decay equation shows transmutation (NUCLEAR CHANGE):
example: 14C undergoes beta decay
14
C 
0
-1
e + X solve for X
balance top numbers… 14 = 0 + X … X must be 14
balance bottom numbers… look up C atomic number = 6 = -1 + X… X is 7 NOT 5


A transmutation may be natural… One thing on the left side of the arrow
A transmutation may be INDUCED or ARTIFICIAL… we make it happen… there are
two or more things on the left side of the arrow.
5. Half-Life is the time for ½ of a radioactive sample to decay (TABLE N). Half life information :
Half Life
0
Time
0
Fraction Left
1
Amount Left
6. Fission - the splitting of the nucleus of atoms takes place in a nuclear reactor.
This process is EXOTHERMIC, producing a lot of energy.
7. Fusion is the nuclear process of joining 2 nuclei together to produce energy. Fuels
for fusion are isotopes of hydrogen, deuterium and tritium. (Isotopes of Hydrogen
found on Table J)
8. Radioactive elements are helpful:
 Iodine - 131 - used in diagnosis of thyroid disorders (cancer)
 Cobalt-60 - used in cancer therapy
 Carbon -14 - used in radioactive dating of fossils
 Uranium-238 - used for geological dating
10