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Chm 1.1. Matter: Properties and Change - Analyze the Structure of Atoms and Ions - Chapter 3,
4 and 21
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. Whose series of experiments identified the nucleus of the atom?
a. Rutherford
c. Chadwick
b. Dalton
d. Bohr
2. In Rutherford's experiments, alpha particles
a. passed through a tube containing gas.
c. collided with electrons.
b. were used to bombard a cathode plate.
d. were used to bombard thin metal foil.
3. In Rutherford's experiments, most of the particles
a. bounced back.
c. were absorbed by the foil.
b. passed through the foil.
d. combined with the foil.
4. Because most particles fired at metal foil passed straight through, Rutherford concluded that
a. atoms were mostly empty space.
c. electrons formed the nucleus.
b. atoms contained no charged particles.
d. atoms were indivisible.
5. Because a few alpha particles bounced back from the foil, Rutherford concluded that they were
a. striking electrons.
b. indivisible.
c. repelled by densely packed regions of positive charge.
d. magnetic.
6. Rutherford's experiments led him to conclude that atoms contain massive central regions that have
a. a positive charge.
c. no charge.
b. a negative charge.
d. both protons and electrons.
7. A positively charged particle with mass 1.673  10–24 g is a(n)
a. proton.
c. electron.
b. neutron.
d. positron.
8. A nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a(n)
a. nuclide.
c. electron.
b. neutron.
d. isotope.
9. The nucleus of an atom has all of the following characteristics except that it
a. is positively charged.
c. contains nearly all of the atom's mass.
b. is very dense.
d. contains nearly all of the atom's volume.
10. An atom is electrically neutral because
a. neutrons balance the protons and electrons.
b. nuclear forces stabilize the charges.
c. the numbers of protons and electrons are equal.
d. the numbers of protons and neutrons are equal.
11. Most of the volume of an atom is occupied by the
a. nucleus.
c. electrons.
b. nuclides.
d. protons.
12. The smallest unit of an element that can exist either alone or in combination with other such particles of the
same or different elements is the
a. electron.
c. neutron.
b. proton.
d. atom.
____ 13. Isotopes are atoms of the same element that have different
a. principal chemical properties.
c. numbers of protons.
b. masses.
d. numbers of electrons.
____ 14. All isotopes of hydrogen contain
a. one neutron.
c. one proton.
b. two electrons.
d. two nuclei.
____ 15. The atomic number of oxygen, 8, indicates that there are eight
a. protons in the nucleus of an oxygen atom.
b. oxygen nuclides.
c. neutrons outside the oxygen atom's nucleus.
d. energy levels in the oxygen atom's nucleus.
____ 16. The total number of protons and neutrons in the nucleus of an atom is its
a. atomic number.
c. mass number.
b. Avogadro number.
d. average atomic mass.
____ 17. As the mass number of an element’s isotopes of an element increases, the number of protons
a. decreases.
b. increases.
c. remains the same.
d. doubles each time the mass number increases.
____ 18. As the atomic number increases, the number of electrons in a neutral atom
a. decreases.
c. remains the same.
b. increases.
d. is undetermined.
____ 19. All atoms of the same element have the same
a. atomic mass.
c. mass number.
b. number of neutrons.
d. atomic number.
____ 20. Atoms of the same element can differ in
a. chemical properties.
c. atomic number.
b. mass number.
d. number of protons and electrons.
____ 21. The average atomic mass of an element is the average of the atomic masses of its
a. naturally occurring isotopes.
c. radioactive isotopes.
b. two most abundant isotopes.
d. artificial isotopes.
____ 22. The atomic mass of an element listed in the periodic table is the
a. average atomic mass.
b. relative atomic mass of the most abundant isotope.
c. relative atomic mass of the most abundant radioactive isotope.
d. mass number of the least abundant isotope.
____ 23. An aluminum isotope consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is
a. 13.
c. 27.
b. 14.
d. 40.
____ 24. Chlorine has atomic number 17 and mass number 35. It has
a. 17 protons, 17 electrons, and 18 neutrons.
b. 35 protons, 35 electrons, and 17 neutrons.
c. 17 protons, 17 electrons, and 52 neutrons.
d. 18 protons, 18 electrons, and 17 neutrons.
____ 25. Carbon-14 (atomic number 6), the radioactive nuclide used in dating fossils, has
a. 6 neutrons.
c. 10 neutrons.
b. 8 neutrons.
d. 14 neutrons.
____ 26. Phosphorus-33 (atomic number 15) contains
a. 33 protons.
c. 33 neutrons.
b. 18 neutrons.
d. 18 protons.
____ 27. Neon-22 contains 12 neutrons. It also contains
a. 12 protons.
c. 22 electrons.
b. 22 protons.
d. 10 protons.
____ 28. The distance between two successive peaks on adjacent waves is its
a. frequency.
c. quantum number.
b. wavelength.
d. velocity.
____ 29. A quantum of electromagnetic energy is called a(n)
a. photon.
c. excited atom.
b. electron.
d. orbital.
____ 30. The energy of a photon is related to its
a. mass.
c. frequency.
b. speed.
d. size.
____ 31. A line spectrum is produced when an electron moves from one energy level
a. to a higher energy level.
c. into the nucleus.
b. to a lower energy level.
d. to another position in the same sublevel.
____ 32. The Bohr model of the atom was an attempt to explain hydrogen's
a. density.
c. mass.
b. flammability.
d. line-emission spectrum.
____ 33. For an electron in an atom to change from the ground state to an excited state,
a. energy must be released.
b. energy must be absorbed.
c. radiation must be emitted.
d. the electron must make a transition from a higher to a lower energy level.
____ 34. If electrons in an atom have the lowest possible energies, the atom is in the
a. ground state.
c. excited state.
b. inert state.
d. radiation-emitting state.
____ 35. Bohr's theory helped explain why
a. electrons have negative charge.
b. most of the mass of the atom is in the nucleus.
c. excited hydrogen gas gives off certain colors of light.
d. atoms combine to form molecules.
____ 36. According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus
a. in specific, allowed orbits.
b. in one fixed orbit at all times.
c. at any of an infinite number of distances, depending on its energy.
d. counterclockwise.
____ 37. The electron in a hydrogen atom has its lowest total energy when the electron is in its
a. neutral state.
c. ground state.
b. excited state.
d. quantum state.
____ 38. The change of an atom from an excited state to the ground state always requires
a. absorption of energy.
b. emission of electromagnetic radiation.
c. release of visible light.
d. an increase in electron energy.
____ 39. According to Bohr, electrons cannot reside at ____ in the figure below.
____ 40.
____ 41.
____ 42.
____ 43.
a. point A
c. point C
b. point B
d. point D
Which model of the atom explains why excited hydrogen gas gives off certain colors of light?
a. the Bohr model
c. Rutherford's model
b. the de Broglie model
d. Planck's theory
The region outside the nucleus where an electron can most probably be found is the
a. electron configuration.
c. s sublevel.
b. quantum.
d. electron cloud.
A three-dimensional region around a nucleus where an electron may be found is called a(n)
a. spectral line.
c. orbital.
b. electron path.
d. orbit.
According to the quantum theory of an atom, in an orbital
a. an electron's position cannot be known precisely.
b. an electron has no energy.
c. electrons cannot be found.
d. electrons travel around the nucleus on paths of specific radii.
____ 44. What does the 4 in
represent?
a. the mass number
b. the atomic number
c. the number of protons
d. the number of neutrons
____ 45. What does the 101 in
represent?
a. the mass number
c. the nuclide number
b. the atomic number
d. the number of neutrons
____ 46. What does the 218 in polonium-218 represent?
a. the mass number
c. the mass defect
b. the atomic number
d. the neutron number
____ 47. Reactions that affect the nucleus of an atom are called
a. fusions.
c. radioactive decays.
b. fissions.
d. nuclear reactions.
____ 48. Balance the following equation:
____
a.
c.
b.
d.
____ 49. Balance the following equation:
a.
b.
+ ____
c.
d.
____ 50. Balance the following equation:
a.

+
c.
b.
____ 51. Balance the following equation:
a.
b.
____ 52. Balance the following equation:
a.
b.
+ ____
d.
+ ____
+
c.
d.
____ +
c.
d.
____ 53. The spontaneous disintegration of a nucleus into a slightly lighter and more stable nucleus, accompanied by
emission of particles, electromagnetic radiation, or both, is
a. nuclear fusion.
c. radioactive decay.
b. nuclear radiation.
d. nuclear fission.
____ 54. Which describes particles or electromagnetic radiation emitted from the nucleus during radioactive decay?
a. harmless nuclear fallout
c. transmutation
b. nuclear radiation
d. daughter nuclides
____ 55. During radioactive decay, the nucleus disintegrates into
a. a lighter and more stable nucleus.
c. a lighter and less stable nucleus.
b. a heavier and more stable nucleus.
d. a heavier and less stable nucleus.
____ 56. Alpha particles are
a. electrons.
c. electromagnetic waves.
b. helium nuclei.
d. neutrons.
____ 57. Beta particles are
a. electrons.
c. electromagnetic waves.
b. helium nuclei.
d. neutrons.
____ 58. Gamma rays are
a. electrons.
c. electromagnetic waves.
b. helium nuclei.
d. neutrons.
____ 59. Which of the following is the symbol for an alpha particle?
a.
c.
b.
d.
____ 60. Which of the following is the nuclear symbol for a beta particle?
a.
c.
b.
d.
____ 61. The half-life of an isotope is the time required for half the nuclei in a sample to
a. undergo radioactive decay.
c. undergo nuclear fusion.
b. undergo nuclear fission.
d. react chemically.
____ 62. How many half-lives are required for three-fourths of the nuclei of one isotope in a sample to decay?
a.
c. 2
b.
d. 3
____ 63. What is the half-life of an isotope if 125 g of a 500 g sample of the isotope remain after 3.0 years?
a. 1.5 years
c. 3.5 years
b. 2.5 years
d. 4.5 years
____ 64. Which of the following generally have the lowest penetrating ability?
a. alpha particles
c. gamma rays
b. beta particles
d. All have the same penetrating ability.
____ 65. Which of the following has the greatest penetrating ability?
a. alpha particles
c. gamma rays
b. beta particles
d. All have the same penetrating ability.
____ 66. Which statement does not describe fission?
a. A neutron starts the process.
b. Several neutrons are emitted.
c. Stable, lightweight nuclei start the process.
d. A very heavy nucleus splits into several medium-weight nuclei.
____ 67. Which of the illustrations below represents a fission reaction?
a. A
b. B
c. C
d. D
____ 68. At present, fusion reactions
a. cannot be used to produce energy in reactors.
b. produce the energy in some nuclear power plants.
c. produce the energy in most nuclear power plants.
d. produce the energy in all recent nuclear power plants.
Short Answer
69. Describe the nucleus of an atom.
70. Give the location and relative charge of a proton.
71. What is the atomic number of an atom?
72. What is the mass number of an atom?
73. What is an isotope?
74. What is the relationship between isotopes, mass number, and neutrons?
75. Briefly describe alpha particles, beta particles, and gamma rays.
Problem
76. Phosphorus-32 has a half-life of 14.3 days. How many milligrams of phosphorus-32 remain after 71.5 days if
you start with 4.00 mg of the isotope?
77. What is the half-life of an isotope if after 2.00 weeks you have 31.25 g remaining from a 250.0 g starting
sample size?
Essay
78. Compare fusion and fission.
Chm 1.1. Matter: Properties and Change - Analyze the Structure of Atoms and Ions - Chapter 3,
4 and 21
Answer Section
MULTIPLE CHOICE
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Solution:
DIF: I
63. ANS: A
Solution:
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SHORT ANSWER
69. ANS:
An atom’s very small central region, which is made up of protons and neutrons.
DIF: I
REF: 2
OBJ: 2
70. ANS:
A proton is a subatomic particle with a positive charge that is located in the nucleus of an atom.
DIF: I
REF: 2
OBJ: 3
71. ANS:
The number of protons in the nucleus of an atom.
DIF: I
REF: 3
OBJ: 1
72. ANS:
The sum of the number of protons and neutrons in an atom.
DIF: I
REF: 3
OBJ: 1
73. ANS:
An atom that has the same number of protons as another atom (of the same element), but a different number
of neutrons.
DIF: I
REF: 3
OBJ: 1
74. ANS:
Isotopes are atoms of the same element with different numbers of neutrons, and therefore, different mass
numbers.
DIF: II
REF: 3
OBJ: 2
75. ANS:
Alpha particles are helium nuclei that are emitted from heavy elements. Beta particles are high-energy
electrons emitted from nuclei when neutrons become protons. Gamma rays are high-energy electromagnetic
waves.
DIF: II
REF: 2
OBJ: 2
REF: 2
OBJ: 3
PROBLEM
76. ANS:
0.125 mg
Solution:
DIF: III
77. ANS:
half-life = 4.67 days
Solution:
DIF: III
REF: 2
OBJ: 3
ESSAY
78. ANS:
Fission and fusion are two processes that change the number of protons. In fission, a heavy nucleus breaks up,
decreasing the number of protons. In fusion, light nuclei join, increasing the number of protons.
DIF: II
REF: 4
OBJ: 1