Atomic Theory Problems
1. Determine the molar mass of (82) Lead
 204Pb 203.973029 g/mol
 206Pb 205.974449 g/mol
 207Pb 206.975881 g/mol
 208Pb 207.976636 g/mol
1.40 %
24.1 %
22.1 %
52.4 %
2. The different variations of lead listed above are called ________________
3. Define the term from number 2
4. List all the noble gases
5. Identify the numbers of protons and neutrons from each variation of lead in
problem number 1
6. What is a mass number?
7. Identify the number of protons and electrons in each of the following:
a. I b. Mg +2
c. Cu +
8. What are the things given in number 7 called?
9. Name the number that identifies the number of protons in an element and where
can it be found?
10. What is the closest noble gas to Magnesium?
11. Identify the ions that each of the following elements will form and describe how
each will form:
a. Se
b. Ga
c. Ba
d. Br
12. What is a positive ion called and how is it formed?
13. How many neutrons and protons are in
64
31
Ga ?
14. Can the mass number be found on the periodic table?
15. How many electrons and protons are in the ion commonly formed by oxygen?
16. Determine the molar mass of (92) Uranium
 234U
234.040946 g/mol
235

U
235.043923 g/mol
238

U
238.050783 g/mol
0.0055 %
0.7200 %
99.2745 %
17. What is a negative ion called and how is it formed?
18. How many electrons are in a neutral gold atom?
19. Write the symbol for the isotope containing 20 protons and 22 neutrons
20. Calculate the molar mass of (71) Lutetium
 175Lu
174.940768 g/mol
176

Lu
175.942682 g/mol
97.41 %
2.59 %
21. Identify the ions that will form from each of the following elements and name the
specific type of each.
a. Sr
b. S
c. Cl
d. Al
e. Na
Atomic Theory Problems Solutions
1. Determine the molar mass of (82) Lead
 204Pb 203.973029 g/mol
 206Pb 205.974449 g/mol
 207Pb 206.975881 g/mol
 208Pb 207.976636 g/mol
1.40 %
24.1 %
22.1 %
52.4 %
2.855622406
49.639842209
45.741669701
108.979757264
207 g/mol
2. The different variations of lead listed above are called __Isotopes_
3. Define the term from number 2
Elements with the same number of protons but different numbers of
neutrons
4. List all the noble gases
He, Ne, Ar, Kr, Xe, Rn
5. Identify the numbers of protons and neutrons from each variation of lead in
problem number 1
All have 82 protons (204) has 122 neutrons, (206) 124, (207) 125,
(208) 126
6. What is a mass number?
The sum of the protons and neutrons
7. Identify the number of protons and electrons in each of the following:
a. I 53 p+, 54 eb. Mg +2
12 p+, 10 ec. Cu +
29 p+, 28 e-
8. What are the things given in number 7 called?
Ions
9. Name the number that identifies the number of protons in an element and where
can it be found?
Atomic number, on the periodic table
10. What is the closest noble gas to Magnesium?
Neon, Ne
11. Identify the ions that each of the following elements will form and describe how
each will form:
a. Se
Se-2, formed by gaining 2 eb. Ga
Ga+3, formed by losing 3 electrons
c. Ba
Ba+2, formed by losing 2 electrons
d. Br
Br - , formed by gaining 1 electron
12. What is a positive ion called and how is it formed?
Cation, formed by losing electrons
13. How many neutrons and protons are in
31 p+ and 33 no
64
31
Ga ?
14. Can the mass number be found on the periodic table?
Nope
15. How many electrons and protons are in the ion commonly formed by oxygen?
O-2, 8 protons, 10 electrons
16. Determine the molar mass of (92) Uranium
 234U
234.040946 g/mol
235

U
235.043923 g/mol
238

U
238.050783 g/mol
0.0055 %
0.7200 %
99.2745 %
0.012872252
1.6923162456
236.32372457
238.029 g/mol
17. What is a negative ion called and how is it formed?
Anion, formed by gaining electrons
18. How many electrons are in a neutral gold atom?
79 electrons
19. Write the symbol for the isotope containing 20 protons and 22 neutrons
42
20 Ca
20. Calculate the molar mass of (71) Lutetium
 175Lu
174.940768 g/mol
97.41 %
170.4098021
176

Lu
175.942682 g/mol
2.59 %
4.5569154638
175.0 g/mol
21. Identify the ions that will form from each of the following elements and name the
specific type of each.
a. Sr
Sr+2 , Cation
b. S
S-2, anion
c. Cl
Cl-, anion
d. Al
Al+3, cation
e. Na
Na+, cation