PA
Problem Set 4
Chapters 4 and 25
Nuclear Chemistry
Essay Due Oct 30 th
Due Thursday Oct 24 th

Your work is to be done on separate sheets of paper.
Test Wednesday October 30

All of the papers should be stapled together in the upper left hand corner with this th question sheet at the back of the packet.

Each of your responses should be numbered the same way as it appears on this packet.
Conceptual Questions
1) State the law of conservation of mass.
2) Why are atoms unstable?
3) How do unstable atoms gain stability?
4) A radioactive element having atomic number 82 and atomic mass 214 loses a beta particle, 0,–1

. What is the resulting particle?
5) What type of decay is the reaction below, and what isotope completes this nuclear equation? 27,13 Al + 2,1 H

4,2 He + ?
Practice Questions
6) Complete this chart on the three types of radioactive decay
Type
Alpha
Symbol Mass (amu) Charge
Beta
Gamma
7) If the radioactive atom 238, 92 U emits an alpha particle, the atom remaining is represented by
(A) 238, 92 U (B) 236, 92 Th (C) 234, 92 U (D) 234, 90 Th (E) 234, 91 Pa
8) What term completes this equation? 30,14 Si + ?

32,16 S + 0,–1 e
(A) 4,2 He (B) 2,1 H (C) 1,1 H (D) 0,–1 e
9) What particle is emitted when lead–214, 214, 82 Pb, undergoes natural radioactive decay to bismuth–214, 214, 83 Bi?
(A) an alpha particle, 4,2 He
(B) a beta particle, 0,–1 e (D)
(C) a proton, a neutron, 1,0 n
1,1 H
Extension Question
10) Recently Alexander Valterovich Litvinenko was poisoned by radioactive polonium-210. a.
Research who he was and why he was poisoned. b.
Find out what polonium-210 does to people.

c.
Write the nuclear reaction of polonium-210 decaying into lead-206 via an alpha decay.
Chapter 25 Nuclear Chemistry Read Chapter 25
After having read through chapter 25, respond to these conceptual questions.
11) Define the following terms: a.
critical mass b.decay c.
fission d.fusion e.
f.
half life transmutation g.radioisotope
12) Make (or find) a graphical timeline of the development of modern atomic theory with at least 10 important dates and/or discoveries.
After having read through chapter 25, respond to these practice questions.
13) Which type of radiation has a +2 charge? a.
Alpha b. beta c. gamma d. neutron
14) Which type of radiation generates the highest energy – is the “hardest” to block? a.
Alpha b. beta c. gamma d. neutron
15) Finish the following nuclear reactions. Tell if they are alpha or beta decays. a.
238
92
U
 234
Th + ____ c.
222
Rn
 4
___ + He b.
19
F

19
___+ Ne d.
210
At

0
___ +

16) What element was the first man made (synthetic) by scientists?
17) How many grams of sample are left after 20 minutes if 100 grams start decaying with a half life of 5 minutes?
18) How long will it take 100 grams of radioactive sample to decay so that only 6.25 grams remain and the samples half life is 3 days?
19) How long is the half life of an isotope if 2.0 grams of sample remain from a 64 gram sample after 30 years?
After having read through chapter 25, respond to these extension questions.
20) Element number 96 is named Curium. Do you think Marie and Pierre Curie did enough in the advancement of science to have an element named after them?
Explain.

21) Thorium-231 is a radioactive isotope of thorium. It decays in ten steps to form lead-207. The ten steps are:

. Write this decay series.
Answers to Practice Problems
6) Complete this chart on the three types of radioactive decay
Type
Alpha
Beta
Gamma
Symbol



Mass (amu)
4 amu
0 amu
0 amu
Charge
+2
-1
No charge
7) (D)
15)
8) (B) 9) (B) 13) a. 14) c a.
b.
238
92
U
 234 4 c.
222
Rn
 218 4
Po + He
19
F
 0 19
9 -1
 alpha
+ Ne
10 d.
210
At
85
 210 0
Rn +
86 alpha
- 1

16) Oxygen-17
Beta
17) 6.25 g 18) 12 days beta
19) 6 years