Matching
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Match each item with the correct statement below. a. | proton | d. | electron | b. | nucleus | e. | neutron | c. | atom | | | | |
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1.
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the
smallest particle of an element that retains the properties of that element
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2.
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a
positively charged subatomic particle
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3.
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a
negatively charged subatomic particle
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4.
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a
subatomic particle with no charge
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5.
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the
central part of an atom, containing protons and neutrons
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Match each item with the correct statement below. a. | mass
number | d. | atomic
mass | b. | atomic mass
unit | e. | isotope | c. | atomic number | | | | |
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6.
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atoms
with the same number of protons, but different numbers of neutrons in the nucleus of an
atom
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7.
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the
total number of protons and neutrons in the nucleus of an atom
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8.
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the
number of protons in the nucleus of an element
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9.
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the
weighted average of the masses of the isotopes of an element
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10.
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one-twelfth the mass of a carbon atom having six protons and six
neutrons
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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11.
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Which
of the following was NOT among Democritus’s ideas? a. | Matter consists
of tiny particles called atoms. | b. | Atoms are indivisible. | c. | Atoms retain
their identity in a chemical reaction. | d. | Atoms are indestructible. | | |
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12.
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Which
of the following is NOT a part of Dalton's atomic theory? a. | All elements are
composed of atoms. | b. | Atoms are always in motion. | c. | Atoms of the
same element are identical. | d. | Atoms that combine do so in simple whole-number
ratios. | | |
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13.
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Dalton hypothesized that atoms are indivisible and that all atoms of an element are
identical. It is now known that ____. a. | all of Dalton's hypotheses are
correct | b. | atoms of an element can have different numbers of
protons | c. | atoms are divisible | d. | all atoms of an
element are not identical but they must all have the same mass | | |
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14.
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All
atoms are ____. a. | positively
charged, with the number of protons exceeding the number of electrons | b. | negatively
charged, with the number of electrons exceeding the number of protons | c. | neutral, with
the number of protons equaling the number of electrons | d. | neutral, with
the number of protons equaling the number of electrons, which is equal to the number of
neutrons | | |
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15.
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The
atomic number of an element is the total number of which particles in the nucleus? a. | neutrons | c. | electrons | b. | protons | d. | protons and electrons | | | | |
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16.
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What
does the number 84 in the name krypton-84 represent? a. | the atomic
number | c. | the sum of the
protons and electrons | b. | the mass number | d. | twice the number of protons | | | | |
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17.
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Isotopes of the same element have different ____. a. | numbers of
neutrons | c. | numbers of
electrons | b. | numbers of protons | d. | atomic numbers | | | | |
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18.
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How
many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125
contain? a. | 50 protons, 50
electrons, 75 neutrons | c. | 120 neutrons, 50
protons, 75 electrons | b. | 75 electrons, 50 protons, 50
neutrons | d. | 70 neutrons, 75
protons, 50 electrons | | | | |
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19.
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Select the correct symbol for an atom of tritium.
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20.
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In
which of the following is the number of neutrons correctly represented? a. |  F has 0 neutrons. | c. |  Mg has 24 neutrons. | b. |  As has 108
neutrons. | d. |  U has 146 neutrons. | | | | |
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21.
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How
do the isotopes hydrogen-1 and hydrogen-2 differ? a. | Hydrogen-2 has one more electron than
hydrogen-1. | b. | Hydrogen-2 has one neutron; hydrogen-1 has
none. | c. | Hydrogen-2 has two protons; hydrogen-1 has
one. | d. | Hydrogen-2 has
one proton; hydrogen-1 has none. | | |
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22.
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What
unit is used to measure weighted average atomic mass? a. | amu | c. | angstrom | b. | gram | d. | nanogram | | | | |
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23.
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Which
of the following equals one atomic mass unit? a. | the mass of one electron | b. | the mass of one
helium-4 atom | c. | the mass of one carbon-12 atom | d. | one-twelfth the
mass of one carbon-12 atom | | |
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24.
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Why
do chemists use relative masses of atoms compared to a reference isotope rather than the actual
masses of the atoms? a. | The actual mass of an electron is very large compared to the
actual mass of a proton. | b. | The actual masses of atoms are very small and difficult to work
with. | c. | The number of subatomic particles in atoms of different
elements varies. | d. | The actual masses of protons, electrons, and neutrons are not
known. | | |
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Short Answer
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25.
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List
the number of protons, neutrons, and electrons in  C.
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26.
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Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37. The atomic mass of
chlorine is 35.45. Which of these two isotopes of chlorine is more abundant?
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27.
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Consider an element Z that has two naturally occurring isotopes with the following
percent abundances: the isotope with a mass number of 19.0 is 55.0% abundant; the isotope with a mass
number of 21.0 is 45.0% abundant. What is the average atomic mass for element Z?
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28.
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A
fictitious element X is composed of 10.0 percent of the isotope  , 20.0 percent of the isotope  , and 70.0
percent of the isotope  . Estimate the
atomic mass of element X.
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Numeric Response
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29.
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Use
the periodic table to determine the number of electrons in a neutral atom of lithium.
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30.
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Use
the periodic table to determine the number of protons in an atom of barium.
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31.
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What
is the mass number for an oxygen atom that has 10 neutrons in its nucleus?
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Essay
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32.
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Explain how electron microscopy and scanning tunneling microscopes have contributed to
the understanding of atoms.
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33.
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What
observations by Rutherford led to the hypothesis that atoms are mostly empty space, and that almost
all of the mass of the atom is contained in an atomic nucleus?
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