1. 66. How many protons and electrons are contained in an atom of element 44?
element 44 = atomic # 44
44 protons
44 electrons

2. 67. A carbon atom has a mass number of 12 and an atomic number of 6
67. A carbon atom has a mass number of 12 and an atomic number of 6. How many neutrons does it have?
mass number (p + n) 12
atomic number (p) - 6
= # of neutrons 6 n

3. 68. An isotope of mercury has 80 protons and 120 neutrons
68. An isotope of mercury has 80 protons and 120 neutrons. What is the mass number of the isotope?
protons
+ neutrons
= Mass number

4. 69. An isotope of xenon has an atomic number of 54 and contains 77 neutrons. What is the xenon isotope’s mass number?
protons
+ neutrons
= Mass number

5. 70. Is an atom has 18 electrons, how many protons does it have?

6. 72. Fill in the blank Cl Zr 17 40 35 37 90 92 18 20 50 52 Element
Atomic Number 17 40
Mass Number 35 37 90 92
Protons
Neutrons 18 20 50 52
Electrons

7. 73. How many electrons, protons, and neutrons are contained in each?
electrons protons neutrons Cs
b) Co
c) Tm
d) Zn

8. 74. How many electrons, protons, and neutrons are contained in each?
electrons protons neutrons
Gallium
b) fluorine
c) titanium
d) tantalum

9. 76. Ga, which has atomic mass of 69
76. Ga, which has atomic mass of amu, has two naturally occurring isotopes, Ga-69 and Ga-71. Which isotope occurs in greater abundance? Explain.
Ga- 69 must be more abundant because the atomic mass of gallium is closer to the mass of Ga-69 than the mass of Ga-71

10. 77. Silver has two isotopes 107 47 Ag, which has a mass of 106
77. Silver has two isotopes Ag, which has a mass of amu and a percent abundance of 52.00% and Ag , which has a mass of amu and a percent abundance of 48.00%. What is the atomic mass of silver?
x =
x =
amu

11. 78. Data for chromium’s four naturally occurring isotopes are provided in the table. Calculate the atomic mass (amu).
Isotope
Percent Abundance
Mass (amu)
Cr- 50
4.35
49.946
Cr- 52
83.79
51.941
Cr- 53
9.50
52.941
Cr- 54
2.36
53.939 =
= 43.52 = =
51.99 amu