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Atomic Structure Practice Test
Multiple Choice Identify the choice that best completes the statement or answers the question.
__A__ 1. Whose series of experiments identified the nucleus of the atom?
a. Rutherford
b. Dalton
c. Chadwick
d. Bohr
__A__ 2. A nuclear particle that has about the same mass as a neutron, but with a positive charge, is called a(n)
a. proton.
b. neutron.
c. electron.
d. isotope.
__B__ 3. Which part of an atom has a mass approximately equal to 1/2000 of the mass of a proton or a neutron?
a. nucleus
b. electron
c. proton
d. neutron
__A__ 4. The atomic number of chlorine, 17, indicates that there are seventeen_____.
a. protons in the nucleus.
c. neutrons outside the nucleus.
b. chlorine nuclides.
d. energy levels in the nucleus.
__C__ 5. The total number of protons and neutrons in the nucleus of an atom is its
a. atomic number.
b. atomic weight.
c. mass number.
d. atomic mass.
__D__ 6. All atoms of the same element have the same
a. atomic mass.
b. # of neutrons.
c. mass number.
d. atomic number.
__B__ 7. The average atomic mass of an element
a. is the mass of the most abundant isotope. c. cannot be calculated.
b. may not equal the mass of any isotopes.
d. always adds up to 100.
__C__ 8. Polonium-210 has
a. 210 neutrons.
b. 84 neutrons.
c. 126 neutrons.
d. 105 neutrons.
__D__ 9. Argon-38 contains
a. 38 protons.
b. 20 protons.
c. 33 neutrons.
d. 18 protons.
__A__ 10. When 999/1000 alpha particles passed through the gold foil, this told Rutherford that
a. an atom is mostly b. an atom has a
c. the nucleus has a d. the matter in an
empty space.
nucleus.
positive charge.
atom’s very dense.
_A___ 11. According to the law of conservation of mass, when sodium, hydrogen, and oxygen react to form a compound, the
mass of the compound is ____ the sum of the masses of the individual elements.
a. equal to
c. less than
b. greater than
d. either greater than or less than
__C__ 12. According to Dalton's atomic theory, atoms
a. are destroyed in chemical reactions.
b. can be divided.
c. of each element are identical in size, mass, and other properties.
d. of different elements cannot combine.
__A__ 13. Which of the following statements is true according to modern atomic theory?
a. Atoms of the same element may have different masses.
b. Atoms may be divided in ordinary chemical reactions.
c. Atoms can never combine with any other atoms.
d. Cathode rays are composed of protons..
__B__ 14. When the light from electrified atoms was passed through a prism in Niels Bohr’s experiment,
a. he saw the whole spectrum of colors.
c. he saw electrons jumping to higher levels.
b. he saw narrow bands of a few colors.
d. he saw white light.
__D__ 15. Experiments with cathode rays led to the discovery of the
a. proton.
b. nucleus.
c. neutron.
d. electron.
__A__ 16. Because any element used in the cathode produced electrons, scientists concluded that
a. all atoms contained electrons.
c. atoms were indivisible.
b. only metals contained electrons.
d. atoms carried a negative charge.
__D__ 17. If you change the number of protons in an atom, what is affected?
a. The mass of the atom
c. The charge on the atom
b. The identity of the atom
d. All choices are correct
__C__ 18. 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.
__D__ 19. The nucleus of an atom has all of the following characteristics except that it
a. is positively charged.
b. is very dense.
c. contains nearly all of the atom's mass.
d. contains nearly all of the atom's volume.
__C__ 20. 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.
__B__ 21. Isotopes are atoms of the same element that have different
a. principal chemical properties.
c. numbers of protons.
b. masses.
d. numbers of electrons.
__B__ 22. As the atomic number increases, the number of electrons in a neutral atom
a. decreases.
c. remains the same.
b. increases.
d. is undetermined.
__A__ 23. In determining the atomic mass of elements, the standard is the
a. C-12 atom.
b. C-14 atom.
c. H-1 atom.
d. O-16 atom.
__A__ 24. 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.
__A__ 25. 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.
__D__ 26. Neon-22 contains 12 neutrons. It also contains
a. 12 protons.
b. 22 protons.
c. 22 electrons.
d. 10 protons.
Short Answer/Problem
27. Using the data below, calculate the atomic mass of nitrogen.
isotope
Nitrogen
14
7N
15
7N
% abundance
99.63
0.37
mass
14.003
15.000
28. What is the relationship between isotopes, mass number, and neutrons?
Essay
29. Why do scientists use Dalton's theory, even though parts of it have been proven wrong? Which parts of Dalton’s
theory have been changed?
30. There are two isotopes of chlorine: chlorine-35 and chlorine-37. If the atomic mass of chlorine is 35.45, what can
you conclude about the abundance of each isotope?
Atomic Structure Practice Test
Answer Section
MULTIPLE CHOICE
1. ANS: A
PTS: 1
DIF: I
REF: 2
2. ANS: A
PTS: 1
DIF: I
REF: 2
3. ANS: B
PTS: 1
DIF: I
REF: 2
4. ANS: A
PTS: 1
DIF: II
REF: 3
5. ANS: C
PTS: 1
DIF: I
REF: 3
6. ANS: D
PTS: 1
DIF: I
REF: 3
7. ANS: B
PTS: 1
DIF: I
REF: 3
8. ANS: C
PTS: 1
DIF: III
REF: 3
9. ANS: D
PTS: 1
DIF: III
REF: 3
10. ANS: A
11. ANS: A
PTS: 1
DIF: II
REF: 1
12. ANS: C
PTS: 1
DIF: I
REF: 1
13. ANS: A
PTS: 1
DIF: II
REF: 1
14. ANS: B
PTS: 1
DIF: I
REF: 1
15. ANS: D
PTS: 1
DIF: I
REF: 2
16. ANS: A
PTS: 1
DIF: I
REF: 2
17. ANS: D
PTS: 1
DIF: I
REF: 2
18. ANS: C
PTS: 1
DIF: I
REF: 2
19. ANS: D
PTS: 1
DIF: II
REF: 2
20. ANS: C
PTS: 1
DIF: I
REF: 2
21. ANS: B
PTS: 1
DIF: I
REF: 3
22. ANS: B
PTS: 1
DIF: I
REF: 3
23. ANS: A
PTS: 1
DIF: I
REF: 3
24. ANS: A
PTS: 1
DIF: I
REF: 3
25. ANS: A
PTS: 1
DIF: III
REF: 3
26. ANS: D
PTS: 1
DIF: III
REF: 3
SHORT ANSWER
27. ANS: The statement that mass cannot be created or destroyed in ordinary chemical reactions.
28. ANS: An atom’s very small central region, which is made up of protons and neutrons.
29. ANS: A proton is a subatomic particle with a positive charge that is located in the nucleus of an atom.
30. ANS: The number of protons in the nucleus of an atom.
The sum of the number of protons and neutrons in an atom.
Dalton's theory led to the modern theory of the atom. Although scientists now know that atoms can be divided
and that all atoms of an element are not identical,, most of his early theory is still accepted.
34. ANS: The atomic number equals the number of protons in the nucleus of an atom and also equals the number
of electrons in the neutral atom. The mass number is the sum of the number of protons and neutrons and can
be used, with the atomic number, to find the number of neutrons in each isotope. Each isotope of the element
has a different mass number but the same atomic number as the element.