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I am having a lot of trouble with this activity given to me, I'm not understanding the questions and it would be

great if you could help with me critical thinking questions in the attached assignment? I was able to understand a few of them on the pages before these but these just have me lost. Thank you.critical thinking1.jpg

CHE115_Radioact_activity Chap 11-2019-page0001.jpg

CHE115 - Dr. Fobare
9/6/2019
Name:
ChemActivity #7- Chapter 11
Radioactivity
Model 1: Types of Radioactivity
1. Alpha Decay - loss of a helium nucleus
238
92
90 Th + SHe
2. Beta Decay - loss of a nuclear electron
6C
14N + 0e
3. Gamma Decay - emission of pure, high-energy
electromagnetic radiation
152mDy
152 Dy + by
4. Positron Emission - loss of a nuclear positron
18F
9
180
8
+ e

CHE115_Radioact_activity Chap 11-2019-page0002.jpg

CHEHS — Dr. Fobare
9/6/2019 Table 4.1 The Ionizing Radiation of Radioactivity Radiation Component - Symbols Velocity Penetrating
- Power -
n rays Helium nuclei ‘éHez", 450:, on 5% to 7% of Low
the speed of
light
3 rays Electrons 195', 19 .8, B", [.3 Varies; up to Moderate
90% of the
speed of light
y rays Electromagnetic is. v Speed of light High
waves Critical Thinking Questions: 1. In u—decay, What changes in the mass number are observed? What changes in the atomic
number are observed? 2. In fi—decay, What changes in the mass number are observed? What changes in the atomic
number are observed? 3. In 'y—decay, what changes in the mass number are observed? What changes in the atomic
number are observed? 4. In positron emission, What changes in the mass number are observed? What changes in the
atomic number are observed? 5. Make a checklist for solving radioactive decay equations:

CHE115_Radioact_activity Chap 11-2019-page0003.jpg

CHE115 - Dr. Fobare
9/6/2019
Exercises:
1. Write a reaction for the a-decay of:
149Gd
64
2. Write a reaction for the P-decay of:
210 pb
82
3. Write a reaction for the y-decay of:
40
Ar
4. Write a reaction for the positron emission of:
28 Ni
5. Complete the following reactions and name the type of radioactivity emitted:
73Ga
73 Ge +
150
8
15N +
192pt
78
1880s +
76
W

CHE115_Radioact_activity Chap 11-2019-page0004.jpg

CHE115 - Dr. Fobare
9/6/2019
Model 2: Half-Life
Half-life (1/) is the time for 50% (1/2) of the radiation to
decay.
1 t1/2
2 t1/2
3 t1/2
4 t1/2
5 t1/2
Amount Remaining
100% ----> 50% ---> 25% ---> 12.5% ---> 6.25% ----> 3.125%
Number of half-lives
Initial
sample
1
2
3
4
5
6
8
9
10
10,000
99mTC
half-life = 6 h
Number of radioactive
atoms remaining
5000
1 half-life
2500
2 half-lives
1875
1250
3 half-lives
625
6
12
18 24 30 36
42
48 54
60
Time (h)
Radioactive decay is a first-order process since it is only dependent on the amount of
radioactive element present.
Rate = k[Radioisotope]
A = Age-kt
k =0.693/t1/2 or t1/2 = 0.693/k
4

CHE115_Radioact_activity Chap 11-2019-page0005.jpg

CHE115 - Dr. Fobare
9/6/2019
Exercises:
1. If 30mCi of 99mTc is prepared at 6AM, how much is left at 12:30PM?
Steps in the Solution: a) Look up t1/2 of "9mTc.
b) What is the time interval, t?
c) How many half-lives passed?
d) Count down the half-lives from starting 30m Ci:
e) Estimate the answer:
5

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