a. 150.62 u
b. 150.12 u
*c. 151.01 u
d. 151.80 u
Answer: c
Learning objective 1.3 - describe the structure of the atom.
65. A naturally occurring element consists of two isotopes:
isotope 1 68.5257 u 60.226%
isotope 2 70.9429 u ??????%
What is the average atomic mass of this naturally occurring element?
a. 69.743 u
*b. 69.487 u
c. 69.972 u
d. 69.934 u
Answer: b
Learning objective 1.3 - describe the structure of the atom.
Short-answer questions
66. What are the three classes of elements?
Answer: Metals, nonmetals and metalloids.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
67. Which elements make up the Noble gasses?
Answer: He, Ne, Ar, Kr, Xe, Rn, (Uuo).
Learning objective 1.4 - explain the basis of the periodic table of the elements.
68. The horizontal rows of the periodic table are known as what?
Answer: Periods.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
69. What is the atomic number and atomic mass of nickel?
Answer: Atomic number – 28, atomic mass – 58.69.
Learning objective 1.3 – describe the structure of the atom.
70. What is the atomic number and atomic mass of gold?
Answer: Atomic number – 79 atomic mass – 197.0.
Learning objective 1.3 – describe the structure of the atom.
71. The vertical columns of the periodic table are known as what?
Answer: Groups.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
72. List the halogen elements in increasing atomic mass number.
Answer: F, Cl, Br, I, (At).
Learning objective 1.4 - explain the basis of the periodic table of the elements.
73. What are the properties of metals?
Answer: ductile, malleable, good conductors of heat, good conductors of electricity.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
74. What property of metals allows them to be drawn into wire?
Answer: Ductile.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
75. What property of metals allows them to be beaten into thin sheets?
Answer: Malleable.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
76. For which two metals does the atomic mass number decrease with increasing atomic number?
Answer: Co and Ni.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
77. How many elements are there in the lanthanide series?
Answer: 15.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
78. Why are some atomic masses given in parentheses?
Answer: These elements are unstable and undergo spontaneous radioactive decay.
Learning objective 1.4 - explain the basis of the periodic table of the elements.
79. The value listed for the average atomic mass of bromine is 79.909 u. It consists of two isotopes, one with a mass of 78.9183 u and one with a mass of 80.9163 u. What is the percent, by mass, of the more abundant isotope in naturally occurring bromine?
Answer: 50.415 %
Learning objective 1.3 – describe the structure of the atom.
80. The value listed for the average atomic mass of indium is 114.82 u. It consists of two isotopes, one with a mass of 112.9043 u and one with a mass of 114.9041 u. What is the percent, by mass, of the less abundant isotope in naturally occurring indium?
Answer: 4.205 %
Learning objective 1.3 – describe the structure of the atom.
81. List the five statements of Dalton’s atomic theory.