Physical Science Homework Problems
Richard Goode
PHSC P112
Chapter 8
Problems
1. Give the number of protons, neutrons and electrons in the following elements.
a.
12
6
C
6 Protons, 6 electrons, 6 neutrons
b.
16
8
O
8 Protons, 8 electrons, 8 neutrons
c.
36
17
Cl
17 Protons, 17 electrons, 19 neutrons
d.
238
92
e.
1
1
23
11
f.
U
H
Na
92 Protons, 92 electrons, 146 neutrons
1 Protons, 1 electrons, 0 neutrons
11 Protons, 11 electrons, 12 neutrons
2. Write the following elements in isotopic notation:
3
a. Hydrogen – 3
1
39
b. Potassium – 39
19
35
c. Chlorine – 35
17
197
d. Gold – 197
79
H
K
Cl
Au
Thought Questions
1. An atom has 6 protons in the nucleus. What is the atomic number? What is the name of the
element? How many electrons does the element have?
2. Why is the atomic mass not always a whole number? Explain.
3. Why is the atomic number always a whole number? Explain.
4. Explain the similarities and differences between the isotopes of an element.
Chapter 13 Nuclear reactions
Problems
1. The half-life of iodine – 131 is 8 days. How much will remain after 32 days?
1/16
2. The half-life of cesium -137 is 30 years, how much time is required for a 1000 g sample to reduce
to about 1 g?
300 years
Thought Questions
1. What is radioactive decay?
2. What is half-life? Give an example of the half-life of an isotope, describe the amount remaining
and the time involved for 5 half-lives of your isotope.