X Unit 4:
The Atom:
Theory & Structure
Homework & Handouts
Name: ______________________________
Worksheet #1 – Calculations with Subatomic Particles
Use the periodic table when necessary, complete the table below.
Symbol
Ba
Charge
Number of
Protons
0
10
Number of
Electrons
Number of
Neutrons
11
0
82
27
13
Al +3
+3
21
15
-2
98
42
Mo
Pb
18
16
34
46
63
88
0
+3
207
82
24
0
Mass
Number
Worksheet #2 - Protons, Neutrons, and Electrons Practice Worksheet
Fill in the blanks in the following worksheet. Please keep in mind that the isotope represented by each
space may NOT be the most common isotope or the one closest in atomic mass to the value on the
periodic table.
Element Name
Atomic
Symbol w/
Isotope
Notation
Atomic
number
Protons
11
5B
Neutrons
Electrons
6
31
37
24
+1
89
0
28
39
29
35
43
Charge
0
11
0
43
Pb+2
100
207
102
89
17
70
89
18
100
159
0
225
18
81
O-2
Mass
Number
206
0
16
-2
100
Worksheet #3 – Isotopes & Average Atomic Mass
Answer the following questions regarding average atomic mass and isotopes. Show all work for
problems involving calculations!
1. Define the word “isotope”
2. True or False: Is the mass number of a given isotope the same as the average atomic
mass on the periodic table for that element? Explain!
3. What is the atomic mass of phosphorous if phosphorous-29 has a percent abundance of
35.5%, phosphorous-30 has a percent abundance of 42.6%, and phosphorous-31 has a
percent abundance of 21.9%?
4. Calculate the average atomic mass for the following element given information about
the relevant isotopes:
(Isotope 1) Mass = 20 amu; Isotopic abundance = 90.92%
(Isotope 2) Mass = 21 amu; Isotopic abundance = 0.257%
(Isotope 3) Mass = 22 amu; Isotopic abundance = 8.82%
Looking at the periodic table, which element is this most likely? _____________________
Worksheet #4 – Isotopes & Average Atomic Mass
Complete the following isotope problems. Show all of your work!
1. What is the atomic mass of an element with 3 isotopes with the following information:
Isotope 1 – 42 amu (75% abundance)
Isotope 2 – 44 amu (10% abundance)
Isotope 3 – 45 amu (_____% abundance)
2. Sulfur-32
Sulfur-33
Sulfur-34
Sulfur-36
95.0% abundance
0.76% abundance
4.22% abundance
0.014% abundance
3. (Isotope 1) Mass = 35 amu
(Isotope 2) Mass = 37 amu
75.53%
24.47%
Which element is this? ________________________