Download Midterm Review Teacher Answer Key December 21, 2011 `see

Midterm Review
Teacher Answer Key
December 21, 2011
'see explanation below'
1. Base your answer on the information below.
Ozone, O3(g), is produced from oxygen, O2(g), by electrical discharge during thunderstorms. The
unbalanced accompanying equation (see image) represents the reaction that forms ozone.
Identify the type of bonding between the atoms in an oxygen molecule. [1]
In the O2 molecule, the oxygen atoms share two pairs of electrons. The type of bonding within O 2 is
(nonpolar) covalent.
[1 point]
'see explanation below'
2. Base your answer on the information below.
Ozone, O3(g), is produced from oxygen, O2(g), by electrical discharge during thunderstorms. The
unbalanced accompanying equation (see image) represents the reaction that forms ozone.
Explain, in terms of electron configuration, why an oxygen molecule is more stable than an oxygen atom.
[1]
When the O2 molecule is formed, both oxygen atoms have a complete octet of valence electrons with a
noble gas configuration.
[1 point]
'see explanation below'
3. Base your answer on the information below.
In 1864, the Solvay process was developed to make soda ash. One step in the process is represented by the
balanced equation shown.
NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl
Explain, in terms of electronegativity difference, why the bond between hydrogen and oxygen in a water
molecule is more polar than the bond between hydrogen and nitrogen in an ammonia molecule. [1]
The electronegativity difference between two bonded atoms is a measure of the polarity of the bond. Use
Reference Table S. The electronegativity difference for the O—H bond is 1.4, while the electronegativity
difference for the N—H bond is 0.9. The O—H bond is more polar than the N—H bond.
[1 point]
'see explanation below'
4. Base your answer on the information below.
In 1864, the Solvay process was developed to make soda ash. One step in the process is represented by the
balanced equation shown.
NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl
In the space on the answer sheet or on a separate piece of paper, draw a Lewis electron-dot diagram for the
reactant containing nitrogen in the equation. [1]
Either of the following electron-dot diagrams for NH3 is acceptable for credit:
[1 point]
'see explanation below'
5. Base your answer on the information below.
A student prepared two mixtures, each in a labeled beaker. Enough water at 20. oC was used to make 100
milliliters of each mixture.
Classify each mixture using the term "homogeneous" or the term "heterogeneous." [1]
All solutions are homogeneous (uniform) mixtures. Mixture 1 is homogeneous. The iron filings in water
clearly result in a nonuniform mixture. Mixture 2 is heterogeneous.
[1 point]
'see explanation below'
6. Base your answer on the information below.
A student prepared two mixtures, each in a labeled beaker. Enough water at 20. oC was used to make 100
milliliters of each mixture.
Determine the volume of the Fe filings used to produce mixture 2. [1]
Use the information given in the question and the density formula on Reference Table T:
(see image)
[1 point]
'see explanation below'
7. Base your answer on the information below.
A student prepared two mixtures, each in a labeled beaker. Enough water at 20. oC was used to make 100
milliliters of each mixture.
Describe a procedure to physically remove the water from mixture 1. [1]
Allowing the water to evaporate will leave the solid NaCl behind.
[1 point]
'see explanation below'
8. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a half-life of 138
days and undergoes alpha decay.
State one beneficial use of Po-210. [1]
In the first paragraph, two beneficial uses of polonium-210 are given:


Eliminate static electricity in machinery
Remove dust from camera lenses
Only one of these uses need be given in order to receive credit.
[1 point]
'see explanation below'
9. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a halflife of 138
days and undergoes alpha decay.
Complete the nuclear equation on the answer sheet or on a separate piece of paper for the decay of Po-210,
by writing a notation for the missing product. [1]
In order to complete a nuclear equation, the atomic numbers and the mass numbers on both sides of the
arrow must be equal. Use Reference Table O. The completed nuclear equation for the alpha decay of
polonium-210 is shown:
(see image)
[1 point]
'see explanation below'
10. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a halflife of 138
days and undergoes alpha decay.
Determine the total mass of an original 28.0-milligram sample of Po-210 that remains unchanged after 414
days. [1]
Use the information given in the question and the radioactive decay formula given on Reference Table T:
(see image)
[1 point]
'see explanation below'
11. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
Explain, in terms of both electrons and energy, how the bright-line spectrum of an element is produced. [1]
As excited electrons fall back to lower energy levels, energy is emitted in the form of light.
[1 point]
'see explanation below'
12. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
Identify all the elements in the mixture. [1]
The bright-line spectrum of a mixture of elements will contain all of the lines of each element in the
mixture. Compare the spectra of each element with the spectrum of the mixture. The mixture contains
strontium and lithium.
[1 point]
'see explanation below'
13. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
State the total number of valence electrons in a cadmium atom in the ground state. [1]
Valence electrons are those in the outermost shell of an atom. Use the Periodic Table of the Elements.
Cadmium (Cd, element 48) has the ground-state electron configuration 2-8-18-18-2. Therefore, cadmium
has two (2) valence electrons.
[1 point]
'see explanation below'
14. Base your answers on the information below.
The ionic radii of some Group 2 elements are given in the accompanying table.
a. On the grid on the answer sheet or on a separate piece of paper, mark an appropriate scale on the axis
labeled "Ionic Radius (pm)." [1]
b. On the same grid, plot the data from the data table. Circle and connect the points. [1]
c. Estimate the ionic radius of strontium. [1]
d. State the trend in ionic radius as the elements in Group 2 are considered in order of increasing atomic
number. [1]
e. Explain, in terms of electrons, why the ionic radius of a Group 2 element is smaller than its atomic radius.
[1]
Refer to the accompanying completed graph of ionic radius versus atomic number as shown:
a. One point is awarded for drawing an appropriate scale on the y-axis. An appropriate scale is one that is
large enough for a trend to be seen.
[1 point]
b. One point is awarded for plotting all four points correctly (within ±0.3 of a grid space).
[1 point]
c. Refer to the Periodic Table of the Elements and use the graph. The ionic radius of strontium (Sr, element
38) is 117 pm (±2 pm).
[1 point]
d. Refer to the graph. As the atomic number increases, the ionic radius increases.
[1 point]
e. Group 2 elements lose 2 electrons and become ions with a charge of 2+. Since the valence shell is lost, the
ion has a smaller radius than its corresponding atom.
[1 point]
'see explanation below'
15. Base your answers on the information below.
The ionic radii of some Group 2 elements are given in the accompanying table.
a. On the grid on the answer sheet or on a separate piece of paper, mark an appropriate scale on the axis
labeled "Ionic Radius (pm)." [1]
b. On the same grid, plot the data from the data table. Circle and connect the points. [1]
c. Estimate the ionic radius of strontium. [1]
d. State the trend in ionic radius as the elements in Group 2 are considered in order of increasing atomic
number. [1]
e. Explain, in terms of electrons, why the ionic radius of a Group 2 element is smaller than its atomic radius.
[1]
Refer to the accompanying completed graph of ionic radius versus atomic number as shown:
a. One point is awarded for drawing an appropriate scale on the y-axis. An appropriate scale is one that is
large enough for a trend to be seen.
[1 point]
b. One point is awarded for plotting all four points correctly (within ±0.3 of a grid space).
[1 point]
c. Refer to the Periodic Table of the Elements and use the graph. The ionic radius of strontium (Sr, element
38) is 117 pm (±2 pm).
[1 point]
d. Refer to the graph. As the atomic number increases, the ionic radius increases.
[1 point]
e. Group 2 elements lose 2 electrons and become ions with a charge of 2+. Since the valence shell is lost, the
ion has a smaller radius than its corresponding atom.
[1 point]
'see explanation below'
16. Base your answer on the information below.
Ozone, O3(g), is produced from oxygen, O2(g), by electrical discharge during thunderstorms. The
unbalanced accompanying equation (see image) represents the reaction that forms ozone.
Identify the type of bonding between the atoms in an oxygen molecule. [1]
In the O2 molecule, the oxygen atoms share two pairs of electrons. The type of bonding within O2 is
(nonpolar) covalent.
[1 point]
'see explanation below'
17. Base your answer on the information below.
Ozone, O3(g), is produced from oxygen, O2(g), by electrical discharge during thunderstorms. The
unbalanced accompanying equation (see image) represents the reaction that forms ozone.
Explain, in terms of electron configuration, why an oxygen molecule is more stable than an oxygen atom.
[1]
When the O2 molecule is formed, both oxygen atoms have a complete octet of valence electrons with a
noble gas configuration.
[1 point]
'see explanation below'
18. Base your answer on the information below.
A student prepared two mixtures, each in a labeled beaker. Enough water at 20. oC was used to make 100
milliliters of each mixture.
Describe a procedure to physically remove the water from mixture 1. [1]
Allowing the water to evaporate will leave the solid NaCl behind.
[1 point]
'see explanation below'
19. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a half-life of 138
days and undergoes alpha decay.
State one beneficial use of Po-210. [1]
In the first paragraph, two beneficial uses of polonium-210 are given:


Eliminate static electricity in machinery
Remove dust from camera lenses
Only one of these uses need be given in order to receive credit.
[1 point]
'see explanation below'
20. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a halflife of 138
days and undergoes alpha decay.
Complete the nuclear equation on the answer sheet or on a separate piece of paper for the decay of Po-210,
by writing a notation for the missing product. [1]
In order to complete a nuclear equation, the atomic numbers and the mass numbers on both sides of the
arrow must be equal. Use Reference Table O. The completed nuclear equation for the alpha decay of
polonium-210 is shown:
(see image)
[1 point]
'see explanation below'
21. Base your answer on the information below.
Polonium-210 occurs naturally, but is scarce. Polonium-210 is primarily used in devices designed to
eliminate static electricity in machinery. It is also used in brushes to remove dust from camera lenses.
Polonium-210 can be created in the laboratory by bombarding bismuth-209 with neutrons to create bismuth210. The bismuth-210 undergoes beta decay to produce polonium-210. Polonium-210 has a halflife of 138
days and undergoes alpha decay.
Determine the total mass of an original 28.0-milligram sample of Po-210 that remains unchanged after 414
days. [1]
Use the information given in the question and the radioactive decay formula given on Reference Table T:
(see image)
[1 point]
'see explanation below'
22. Explain, in terms of protons and neutrons, why U-235 and U-238 are different isotopes of uranium. [1]
Isotopes of an element have the same atomic number but different mass numbers. This means that each
isotope has the same number of protons but a different number of neutrons. A U-235 atom has 92 protons
and 143 neutrons, and a U-238 atom has 92 protons and 146 neutrons.
[1 point]
'see explanation below'
23. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
Explain, in terms of both electrons and energy, how the bright-line spectrum of an element is produced. [1]
As excited electrons fall back to lower energy levels, energy is emitted in the form of light.
[1 point]
'see explanation below'
24. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
Identify all the elements in the mixture. [1]
The bright-line spectrum of a mixture of elements will contain all of the lines of each element in the
mixture. Compare the spectra of each element with the spectrum of the mixture. The mixture contains
strontium and lithium.
[1 point]
'see explanation below'
25. Base your answer on the accompanying information.
The accompanying bright-line spectra for three elements and a mixture of elements are shown.
State the total number of valence electrons in a cadmium atom in the ground state. [1]
Valence electrons are those in the outermost shell of an atom. Use the Periodic Table of the Elements.
Cadmium (Cd, element 48) has the ground-state electron configuration 2-8-18-18-2. Therefore, cadmium
has two (2) valence electrons.
[1 point]
'see explanation below'
26. Base your answer on the elements in Group 2 on the Periodic Table.
State the general trend in first ionization energy for the elements in Group 2 as these elements are
considered in order from top to bottom in the group. [1]
Use the Periodic Table of the Elements and Reference Table S. The accompanying table lists the first
ionization energies of the elements in Group 2 (from top to bottom):
As the atomic number of Group 2 elements increases, the first ionization energy decreases. [1 point]
'see explanation below'
27. Base your answer on the elements in Group 2 on the Periodic Table.
State, in terms of the number of electron shells, why the radius of a strontium atom in the ground state is
larger than the radius of a magnesium atom in the ground state. [1]
A strontium atom in the ground state has two more electron shells than a magnesium atom in the ground
state. As a result, a strontium atom is larger than a magnesium atom. [1 point]
'see explanation below'
28. Base your answer on the information below.
In the gold foil experiment, a thin sheet of gold was bombarded with alpha particles. Almost all the alpha
particles passed straight through the foil. Only a few alpha particles were deflected from their original paths.
State one conclusion about atomic structure based on the observation that almost all alpha particles passed
straight through the foil. [1]
Since most of the alpha particles passed through without deflection, Rutherford concluded that atoms consist
mostly of empty space. [1 point]
'see explanation below'
29. Base your answer on the accompanying information.
Explain, in terms of intermolecular forces, why ammonia has a higher boiling point than the other
compounds in the table. [1]
The boiling point of a substance depends on the strength of the intermolecular forces present in the liquid.
Since ammonia has a higher boiling point, it must have stronger intermolecular forces than either liquid
methane or liquid hydrogen chloride. [1 point]
'see explanation below'
30. Base your answer on the information below.
The radioisotope uranium-238 occurs naturally in Earth's crust. The disintegration of this radioisotope is the
first in a series of spontaneous decays.
The sixth decay in this series produces the radioisotope radon-222. The decay of radon-222 produces the
radioisotope polonium-218 that has a half life of 3.04 minutes. Eventually, the stable isotope lead-206 is
produced by the alpha decay of an unstable nuclide.
Explain, in terms of electron configuration, why atoms of the radioisotope produced by the sixth decay in
the U-238 disintegration series do not readily react to form compounds. [1]
Use the Periodic Table of the Elements. Radon (Rn, atomic number 86) is a noble gas. It is found in Group
18. Elements in Group 18 have completed outer (valence) shells of electrons and do not readily form
compounds. [1 point]
'see explanation below'
31. Base your answer on the information below.
The radioisotope uranium-238 occurs naturally in Earth's crust. The disintegration of this radioisotope is the
first in a series of spontaneous decays.
The sixth decay in this series produces the radioisotope radon-222. The decay of radon-222 produces the
radioisotope polonium-218 that has a half life of 3.04 minutes. Eventually, the stable isotope lead-206 is
produced by the alpha decay of an unstable nuclide.
Complete the nuclear equation shown on the accompanying diagram for the decay of the unstable nuclide
that produces Pb-206, by writing a notation for the missing nuclide. [1]
An alpha particle is the nucleus of a helium-4 atom. A nuclear equation is balanced if the sum of the atomic
numbers and the sum of the mass numbers are equal on both sides of the arrow. The complete nuclear
equation is shown in the accompanying image:
The missing nuclide in the equation is Po-210. [1 point]
'see explanation below'
32. Base your answer on the information below.
The radioisotope uranium-238 occurs naturally in Earth's crust. The disintegration of this radioisotope is the
first in a series of spontaneous decays.
The sixth decay in this series produces the radioisotope radon-222. The decay of radon-222 produces the
radioisotope polonium-218 that has a half life of 3.04 minutes. Eventually, the stable isotope lead-206 is
produced by the alpha decay of an unstable nuclide.
Determine the original mass of a sample of Po-218, if 0.50 milligram of the sample remains unchanged after
12.16 minutes. [1]
Use the radioactive decay equation given on Reference Table T: (see image)
[1 point]
'see explanation below'
33. On a separate piece of paper, write an electron configuration for a silicon atom in an excited state. [1]
Refer to the Periodic Table of the Elements. The ground-state electron configuration for an atom of silicon
(Si, atomic number 14) is 2–8–4. An excited atom has one or more of its electrons promoted to a higher
energy level. Many different configurations are possible, including 2-7-5, 1-8-5, and 2-8-3-1.
Note that only one configuration needs to be given in order to receive credit. [1 point]
'see explanation below'
34. Base your answer on the accompanying information.
Identify one element from this table for each type of element: metal, metalloid, and nonmetal. [1]
Refer to the abbreviated Periodic Table of the Elements shown on the accompanying image:
The metals on this table are Sn and Pb. The metalloids are Si and Ge. The nonmetal is C. You need to
choose only one from each category. [1 point]
4
35. An example of a physical property of an element is the element's ability to
1. react with an acid
3. form a compound with chlorine
2. react with oxygen
4. form an aqueous solution
4 A physical property is one that can be measured
without changing the identity of the substance
involved. When an element forms an aqueous
solution, the element retains its identity. For example, 3
36. The accompanying data table shows elements Xx, Yy, and Zz
when Cl2 dissolves in water, the Cl2 molecules
from the same group on the Periodic Table.
remain intact.
WRONG CHOICES EXPLAINED:
(1), (2), (3) In each case, the element changes its
identity from neutral atoms to ions.
What is the most likely atomic radius of element Yy?
1. 103 pm
2. 127 pm
3 Refer to the Periodic Table of the Elements.
Elements Xx, Yy, and Zz are all located in Group 13
and are, respectively, Ga, In, and Tl. The unknown
atomic radius belongs to the element In, (atomic
number 49). Use Reference Table S. The atomic
radius of In is 166 pm.
1. 26
2. 31
2 The symbol in this question represents an atom of
Fe with a mass number of 57. The mass number is the
total number of protons and neutrons in the nucleus
of an atom. Subtract the atomic number (26) from the
mass number to obtain the number of neutrons in this
atom:
3. 166 pm
4. 185 pm
2
37. What is the total number of neutrons in an atom of 5726Fe?
3. 57
4. 83
1
38. Which grouping of circles, when considered in order from the
top to the bottom, best represents the relative size of the atoms of
Li, Na, K, and Rb, respectively?
(57 protons + neutrons) - (26 protons) = 31 neutrons
1 See Reference Table S, and examine the data for the
atomic radii of Li, Na, K, and Rb. The accompanying
table lists these atomic radii:
Note that the atomic radii increase steadily. The
circles represented in choice (1) also show a steady
increase in size.
1. 10
2. 12
1 Use the Periodic Table of the Elements. The atomic
number of Mg is 12. An atom of magnesium has 12
electrons. When the atom forms a 2+ ion, it loses 2
electrons. Therefore, a Mg2+ ion has a total of 10
electrons.
1. positive ion with a radius smaller than the radius of
this atom
1
39. What is the total number of electrons in a Mg 2+ ion?
3. 14
4. 24
1
40. When an atom loses one or more electrons, this atom becomes
a
3. negative ion with a radius smaller than the radius
of this atom
2. positive ion with a radius larger than the radius of
this atom
1 An atom forms a positive ion by losing one or more
electrons. When an atom loses electrons to form an
ion, it "loses" its valence level as well. The resulting
ion has a smaller radius than its parent atom. The
example shown in the accompanying diagram
illustrates this concept:
1. hydroxide
2. oxalate
4. negative ion with a radius larger than the radius of
this atom
4
41. What is the name of the polyatomic ion in the compound
Na2O2?
3. oxide
4. peroxide
2
4 See Reference Table E. Since each sodium ion has 42. Given the balanced equation:
a charge of 1+, the O2 ion in Na2O2 must have a
I + I → I2
charge of 2-. This polyatomic ion is known as the
peroxide ion.
Which statement describes the process represented by this
equation?
1. A bond is formed as energy is absorbed.
3. A bond is broken as energy is absorbed.
2. A bond is formed and energy is released.
4. A bond is broken and energy is released.
2 When two iodine (I) atoms combine, they form a
single bond by sharing a pair of electrons (see
image).
Any time a bond is formed, energy is released.
1. 1 electron
2. 2 electrons
4 A double bond is always formed when two atoms
share 2 pairs or a total of 4 electrons.
1. SrPO4
2. Sr3PO8
4
43. An oxygen molecule contains a double bond because the two
atoms of oxygen share a total of
3. 3 electrons
4. 4 electrons
4
44. Which formula represents strontium phosphate?
3. Sr2(PO4)3
4. Sr3(PO4)2
4 Use the Periodic Table of the Elements and
Reference Table E. Strontium ions have a charge of
4
2+ (Sr2+), and phosphate ions have a charge of 3−
45. Which Lewis electron-dot diagram represents calcium oxide?
3−
(PO4 ). In order to be neutral, there must be 3
strontium ions for every 2 phosphate ions, Sr3(PO4)2.
4 Lewis electron-dot diagrams for simple positive
ions (such as Ca2+) are drawn without their valence
electrons. Lewis electron-dot diagrams for simple
negative ions (such as O2−) are drawn with all 8
valence electrons and enclosed in brackets. Of the
choices given, the Lewis electron-dot diagram shown
in choice (4) meets both criteria.
2
46. Given the bright-line spectra of three elements and the
spectrum of a mixture formed from at least two of these elements:
Which elements are present in this mixture?
1. E and D, only
2. E and G, only
1 To determine the composition of the mixture, its
spectrum must be compared with the spectra of
elements D, E, and G. All of the spectral lines of
elements D and E appear in the spectrum of the
mixture, but only one spectral line of element G is
present in the mixture. Therefore, the mixture
contains only elements D and E.
1. 2.87 d
2. 3.82 d
2 Use the radioactive decay equation on Reference
Table T: (see image)
1. ionic compound
2. molecular compound
3. D and G, only
4. D, E, and G
2
47. What is the half-life of a radioisotope if 25.0 grams of an
original 200.-gram sample of the isotope remains unchanged after
11.46 days?
3. 11.46 d
4. 34.38 d
1
48. Which type of substance can conduct electricity in the liquid
phase but not in the solid phase?
3. metallic element
4. nonmetallic element
1 In order to conduct electricity, mobile charges must
be present. In the solid phase, the ions in ionic
compounds are rigidly held in place and the
substance cannot conduct. When melted, the ions are
released and the substance can conduct electricity
since the ions have become mobile.
Wrong Choices Explained:
(2), (4) Molecular compounds and nonmetallic
elements do not possess mobile charges. They do not
conduct electricity in either the solid or the liquid
phases.
(3) Metallic elements possess mobile electrons in
their structures. They conduct electricity in both the
solid and the liquid phases.
1. The shape of the CO2 molecule is symmetrical.
2. The shape of the CO2 molecule is asymmetrical.
1 Molecules with polar bonds are nonpolar if their
bonds are arranged symmetrically. The two C=O
bonds in CO2 are symmetrically arranged to form a
linear molecule.
1. HI
2. KI
1 A binary compound is molecular when the
1
49. Why is a molecule of CO2 nonpolar even though the bonds
between the carbon atom and the oxygen atoms are polar?
3. The CO2 molecule has a deficiency of electrons.
4. The CO2 molecule has an excess of electrons.
1
50. Which formula represents a molecular compound?
3. KCl
4. LiCl
2
electronegativity difference between its elements is
less than 1.7. Use Reference Table S. Of the choices
given, only choice (1), HI, has an electronegativity
difference less than 1.7.
1. scandium
2. selenium
51. Which element has the greatest density at STP?
3. silicon
4. sodium
2 Use Reference Table S. Of the choices given,
4
choice (2), selenium, has the greatest density at STP. 52. Particles are arranged in a crystal structure in a sample of
1. H2(g)
3. Ar(g)
2. Br2(l)
4. Ag(s)
4 A crystal structure is characteristic of the solid
1
phase. Of the choices given, only choice (4), Ag(s), is 53. The relatively high boiling point of water is due to water
in the solid phase.
having
1. hydrogen bonding
3. nonpolar covalent bonding
2. metallic bonding
4. strong ionic bonding
1 The relatively high boiling points of substances
such as H2O, NH3, and HF are due to the presence of
intermolecular forces known as hydrogen bonding. In
order for hydrogen bonding to occur, hydrogen atoms
2
must be bonded to small, highly electronegative
54. Matter is classified as a
atoms (such as O, N, and F). As a result, the forces
among the molecules of H2O, NH3, and HF are
unusually strong and produce relatively high boiling
points.
1. substance, only
3. homogenous mixture, only
4. homogenous mixture or as a heterogeneous
2. substance or as a mixture of substances
mixture
2 Matter is anything that has mass and volume. This
definition includes substances (elements and
compounds) and mixtures of substances.
1. ammonia
2. copper
2 Only elements cannot be decomposed by chemical
changes. Of the choices given, only choice (2),
copper, is an element. The other choices are
compounds, which can be decomposed by chemical
changes.
1. boiling points
2. densities
1 Distillation is the process by which mixtures of
liquids can be separated due to differences in their
boiling points.
2
55. Which substance can not be decomposed by a chemical
change?
3. propanol
4. water
1
56. A beaker contains both alcohol and water. These liquids can
be separated by distillation because the liquids have different
3. particle sizes
4. solubilities
1. combustion
2. neutralization
4
57. A change in the nucleus of an atom that converts the atom
from one element to another element is called
3. polymerization
4. transmutation
4 Transmutation is defined as the change in the
nucleus of an atom that converts the atom from one
element to another.
2
58. Which particle is emitted from a hydrogen-3 nucleus when it
undergoes radioactive decay?
2 See Reference Tables N and O. The radioisotope
hydrogen-3 (3H) emits beta particles as it decays.
1. 2-8-7-1
2. 2-8-7-2
2 Use the Periodic Table of the Elements. Each
element is accompanied by its ground-state electron
configuration. Since an atom is a neutral particle, the
number of electrons in an electron configuration is
also the atomic number of the element. An atom in an
excited state does not match its ground-state
configuration because one or more electrons have
been promoted to higher energy levels. In choice (2),
2-8-7-2, an electron in the third energy level of the
atom has been promoted to the fourth energy level.
1. H
2. He
4 Malleability (the ability to be shaped) and
conductivity are characteristic properties of metallic
elements. Of the choices given, only choice (4), Sn, is
a metallic element.
1. a decrease in atomic radius
2. a decrease in electronegativity
2
59. Which electron configuration represents an excited state for a
potassium atom?
3. 2-8-8-1
4. 2-8-8-2
4
60. A sample of an element is malleable and can conduct
electricity. This element could be
3. S
4. Sn
2
61. Which general trend is demonstrated by the Group 17
elements as they are considered in order from top to bottom on
the Periodic Table?
3. an increase in first ionization energy
4. an increase in nonmetallic behavior
2 Use the Periodic Table of the Elements and
Reference Table S. As one proceeds down a group
(such as Group 17), the atomic radius increases, the 4
electronegativity decreases, the first ionization energy 62. Which particle has the least mass?
decreases, and the nonmetallic behavior decreases.
4 Use Reference Table O. Of the choices given,
choice (4), 0 -1He, which is an electron, is the least
massive particle.
Wrong Choices Explained:
(1) The symbol 4 2He represents an alpha particle,
which is approximately 8,000 times more massive
than an electron.
(2) The symbol 1 1H represents a proton, which is
approximately 2,000 times more massive than an
electron.
(3) The symbol 1 0n represents a neutron, which is
approximately 2,000 times more massive than an
electron.
1. the atomic mass of each artificially produced
isotope of chlorine, only
2. the relative abundance of each naturally occurring
isotope of chlorine, only
3
63. What information is necessary to determine the atomic mass
of the element chlorine?
3. the atomic mass and the relative abundance of each
naturally occurring isotope of chlorine
4. the atomic mass and the relative abundance of each
naturally occurring and artificially produced isotope
of chlorine
3 By definition, the atomic mass of an element is the
weighted average of the element's naturally occurring
isotopes. In order to calculate such an average, the
mass and relative abundance of each isotope must be
known.
1. equals the number of electrons
2. equals the number of neutrons
1 The mass number of an isotope is the sum of the
number of protons and neutrons contained within its
nucleus.
1. absorbing energy
2. releasing energy
1
64. In an atom of argon-40, the number of protons
3. is less than the number of electrons
4. is greater than the number of electrons
1
65. An electron in a sodium atom moves from the third shell to
the fourth shell. This change is a result of the atom
3. gaining an electron
4. losing an electron
1 By definition, an atom is a neutral particle in which 3
66. Which statement describes oxygen gas, O2(g), and ozone gas,
the numbers of protons and electrons are equal.
O3(g)?
3. They have different molecular structures and
1. They have different molecular structures, only.
different properties.
4. They have the same molecular structure and the
2. They have different properties, only.
same properties.
3 The molecules O2 and O3 represent different forms
of the element oxygen. Since their molecular
3
structures are different, their physical and chemical 67. Which statement describes a chemical property of bromine?
properties are also different.
3. Bromine combines with aluminum to produce
1. Bromine is soluble in water.
AlBr3.
4. Bromine changes from a liquid to a gas at 332 K
2. Bromine has a reddish-brown color.
and 1 atm.
3 A chemical property of a substance always involves
subjecting the substance to a chemical reaction, such
as combining bromine with aluminum to produce
4
AlBr3.
68. An atom of aluminum in the ground state and an atom of
gallium in the ground state have the same
Wrong Choices Explained:
(1), (2), (4) Properties such as solubility, color, and
boiling point are physical properties.
1. mass
2. electronegativity
4 Refer to the Periodic Table of the Elements and
Reference Table S. Aluminum (Al, atomic number
13) and gallium (Ga, atomic number 31) are both
found in Group 13. As such, each ground-state atom
of these two elements contains 3 valence electrons.
1. solution
2. compound
3. total number of protons
4. total number of valence electrons
2
69. Which type of matter is composed of two or more elements
that are chemically combined in a fixed proportion?
3. homogeneous mixture
4. heterogeneous mixture
2 A compound is defined as a combination of two or 1
70. The total number of protons, electrons, and neutrons in each
more elements present in a fixed proportion.
of four different atoms are shown in the accompanying table.
Which two atoms are isotopes of the same element?
1. A and D
2. A and Z
3. X and D
4. X and Z
1 Isotopes of the same element must have the same
atomic number, i.e., protons. Of the choices given,
only choice (1), atoms A and D, have the same
number of protons.
3
71. Which Lewis electron-dot diagram represents an atom in the
ground state for a Group 13 element?
1. (1)
2. (2)
3. (3)
4. (4)
3 Use the Periodic Table of the Elements. All Group
13 elements have 3 valence electrons. Lewis electrondot diagrams display only the valence electrons of the
atom. The diagram shown in choice (3) has 3 valence
electrons.
1. Rb
2. Ra
1 Use the Periodic Table of the Elements. Chlorine
(Cl, atomic number 17) has an oxidation state of –1.
In the compound MCl, the oxidation state of M must
be +1. Of the choices given, only choice (1), Rb
(atomic number 37), has an oxidation state of +1.
1. C6H12O6
2. C2H4O2
3 The empirical formula of a compound is its
molecular formula reduced to the simplest wholenumber ratio possible. Of the choices given, only
choice (3), C3H8O, cannot be reduced further.
Wrong Choices Explained:
(1), (2) The empirical formulas of these compounds
are CH2O.
(4) The empirical formula of this compound is CH2.
1. more protons than neutrons
2. more neutrons than protons
1
72. Which element forms a compound with chlorine with the
general formula MCl?
3. Re
4. Rn
3
73. Which formula is both a molecular and an empirical formula?
3. C3H8O
4. C4H8
4
74. An atom of argon in the ground state tends not to bond with
an atom of a different element because the argon atom has
3. a total of two valence electrons
4. a total of eight valence electrons
4 Use the Periodic Table of the Elements. When
atoms bond, they generally complete a valence shell 3
that will contain either 2 or 8 electrons. Since an atom 75. Which formula represents a molecule having a nonpolar
of argon (Ar, atomic number 18) is a noble gas and
covalent bond?
already has 8 valence electrons, it will not bond with
another atom.
1. (1)
2. (2)
3 Use Reference Table S. In a nonpolar bond, the
electronegativity difference should be as close to 0 as
possible. The electronegativity difference of the C—
C bond in choice (3) is exactly 0.
1. C-14 and C-12
2. Co-60 and Co-59
1 See Reference Table N. Carbon is a component of
all living organisms. The radionuclide C-14 decays to
stable C-12 and has a half-life of 5730 years. This
combination is ideal for determining the age of onceliving organisms, provided that they are not more
than 20,000–25,000 years old.
1. protons, only
2. neutrons, only
3 Protons and neutrons are located in the nucleus of
any atom, carbon included.
Wrong Choice Explained:
(4) Electrons are located outside of the nucleus.
1. passed through the foil
2. remained trapped in the foil
1 In the gold foil experiment, more than 99% of the
alpha particles passed through the gold foil with little
or no deflection. As a result, Rutherford concluded
that most of the volume of each gold atom was empty
space.
1. electron
2. neutron
3. (3)
4. (4)
1
76. Which nuclides are used to date the remains of a once-living
organism?
3. I-131 and Xe-131
4. U-238 and Pb-206
3
77. Which subatomic particles are located in the nucleus of a
carbon atom?
3. protons and neutrons
4. protons and electrons
1
78. The gold foil experiment led to the conclusion that each atom
in the foil was composed mostly of empty space because most
alpha particles directed at the foil
3. were deflected by the nuclei in gold atoms
4. were deflected by the electrons in gold atoms
3
79. Which part of a helium atom is positively charged?
3. nucleus
4. orbital
3 The proton is the only positive particle in an atom.
3
It is located in the nucleus of the atom.
1. an alpha particle
2. an electron
3 A neutron has approximately the same mass as a
proton.
Wrong Choice Explained:
(2) In comparison to the mass of either a proton or a
neutron, the mass of an electron is practically 0.
1. a different molecular structure and different
properties
2. a different molecular structure and the same
properties
1 Diamond and graphite have different molecular
structures. Therefore, they have different chemical
and physical properties.
1. carbon
2. germanium
80. The mass of a proton is approximately equal to the mass of
3. a neutron
4. a positron
1
81. At STP, solid carbon can exist as diamond and graphite.
Compared to the molecular structure and chemical properties of
diamond, graphite has
3. the same molecular structure and different
properties
4. the same molecular structure and the same
properties
4
82. Which Group 14 element is classified as a metal?
3. silicon
4. tin
4 Refer to the Periodic Table of the Elements and the
accompanying diagram. The diagram is a small
portion of the Periodic Table. The metalloids are
shaded in this table. Metallic elements lie below the
metalloids, and nonmetallic elements lie above them. 3
Of the choices given, only choice (4), tin, is a
83. The light emitted from a flame is produced when electrons in
metallic element in Group 14.
an excited state
Wrong Choices Explained:
(1) Carbon is a nonmetallic element.
(2), (3) Germanium and silicon are metalloids.
1. absorb energy as they move to lower energy states 3. release energy as they move to lower energy states
2. absorb energy as they move to higher energy states 4. release energy as they move to higher energy states
3 As electrons in an excited state move to lower
energy levels, they release energy in the form of
electromagnetic radiation (light).
1. As
2. Ga
4 An atom's attraction for electrons in a chemical
bond is measured by its electronegativity. As the
electronegativity increases, the attraction for
electrons also increases. See Reference Table S. Of
the choices given, choice (4), Se (selenium, atomic
number 34), has the highest electronegativity (2.6).
1. H2
2. H2O
2 Molecules with polar bonds will be polar if their
bonds lack symmetry. Of the choices given, only
choice (2), H2O, is a nonsymmetrical molecule.
1. covalent and molecular
2. covalent and metallic
4
84. An atom of which element has the greatest attraction for
electrons in a chemical bond?
3. Ge
4. Se
2
85. Which formula represents a polar molecule?
3. CO2
4. CCl4
3
86. Two categories of compounds are
3. ionic and molecular
4. ionic and metallic
3 Compounds may be classified according to the
bonding of the atoms within the compound. If the
atoms are ions, the compound is classified as ionic. If
the bonds are covalent, the compound is classified as
molecular.
3
87. Which type of bond is found between atoms of solid cobalt?
Wrong Choices Explained:
(2), (4) The term metallic is usually applied to
elements and mixtures of elements, not to
compounds.
1. nonpolar covalent
3. metallic
2. polar covalent
4. ionic
3 Refer to the Periodic Table of the Elements. Cobalt
(Co, atomic number 27) is a transition element and is
therefore metallic.
1. I2(s) --> I2(g)
2. I2(s) --> I2(l)
1
88. Which equation represents sublimation?
3. I2(l) --> I2(g)
4. I2(l) --> I2(s)
1 Sublimation is the phase change from solid to gas,
as illustrated in the equation shown in choice (1).
Wrong Choices Explained:
(2) This equation represents melting or fusion.
(3) This equation represents boiling or vaporization.
(4) This equation represents freezing or solidification.
1. alpha particle
2. beta particle
3
89. Which nuclear emission has no charge and no mass?
3. gamma ray
4. positron
3 See Reference Table O. The two neutral particles
on this table are gamma rays and neutrons. In
addition, gamma rays have no mass.
4
90. Which radioisotope is matched with its decay mode?
1. (1)
2. (2)
3. (3)
4. (4)
4 See Reference Table N. Note that the symbol H-3 is 3
equivalent to the symbol 3H. Of the choices given,
91. Which reaction is accomplished by the release of the greatest
only choice (4), P-32 and β-, are correctly paired.
amount of energy?
1. combustion of 10. g of propane
3. nuclear fission of 10. g of uranium
2. electrolysis of 10. g of water
4. oxidation of 10. g of iron
3 Nuclear reactions such as fission and fusion release
far more energy than ordinary chemical reactions.
Therefore, the fission of 10. g of uranium will release
the greatest amount of energy.
1. stable nuclei emit alpha particles
2. stable nuclei emit beta particles
4 Atoms of I-131 decay spontaneously because the
nuclei of these atoms are unstable. Use Reference
Table N. I-131 is a beta (−) emitter.
1. fewer valence electrons
4
92. Atoms of I-131 spontaneously decay when the
3. unstable nuclei emit alpha particles
4. unstable nuclei emit beta particles
1
93. Compared to the atoms of nonmetals in Period 3, the atoms of
metals in Period 3 have
3. fewer electron shells
2. more valence electrons
1 Valence electrons are the electrons in the outermost
shell of an atom. Refer to the Periodic Table of the
Elements. The metals of Period 3 (Na, Mg, and Al)
have 1, 2, and 3 valence electrons, respectively. The
nonmetals of Period 3 (P, S, and Cl) have 5, 6, and 7
valence electrons, respectively.
1. iodine and silver
2. iodine and xenon
3 Use the Periodic Table of the Elements. Metallic
elements are good conductors of electricity. Of the
choices given, only choice (3), tin and silver, are both
metallic elements.
1. lithium atom
2. potassium atom
3 The first ionization energy measures the amount of
energy needed to remove the most loosely held
electron from a ground-state atom. Use Reference
Table S. Of the choices given, rubidium (Rb), has the
smallest first ionization and, therefore, requires the
least amount of energy to remove its single valence
electron.
1. FeS
2. Fe2S3
4. more electron shells
3
94. Which elements are malleable and good conductors of
electricity?
3. tin and silver
4. tin and xenon
3
95. Which atom in the ground state requires the least amount of
energy to remove its valence electron?
3. rubidium atom
4. sodium atom
2
96. What is the chemical formula of iron(III) sulfide?
3. FeSO3
4. Fe2(SO3)3
2 The first part of the compound's name, iron(III),
means that iron has an oxidation state of +3. Sulfide
is a Group 16 ion with an oxidation state of −2. Since
the compound is neutral, the sum of the oxidation
numbers of iron and sulfide must equal 0. The
formula Fe2S3 has a total oxidation number of 0 since 1
2 · (+3) + 3 · (−2) = 0.
97. Which diagram represents a physical change, only?
Wrong Choices Explained:
(1) FeS is the formula of iron(II) sulfide.
(3) FeSO3 is the formula of iron(II) sulfite.
(4) Fe2(SO3)3 is the formula for iron(III) sulfite.
1 A physical change is one in which atoms or
molecules are rearranged only; there is no
combination or decomposition occurs. Of the choices
given, only choice (1) shows the rearrangement of the
two types of atoms.
Wrong Choices Explained:
(2) The six atoms combine to form two molecules;
this is a chemical change.
(3) Two molecules decompose into eight atoms; this
is a chemical change.
(4) Two molecules combine to form a different
molecule; this is a chemical change.
1. Molecules of Br2 are polar, and molecules of I2 are
nonpolar.
2. Molecules of I2 are polar, and molecules of Br2 are
nonpolar.
4 The phase of a substance at STP depends on the
strength of the intermolecular forces within the
substance. Solids have stronger intermolecular forces
than liquids.
1. +1
2. +2
4
98. Which statement explains why Br2 is a liquid at STP and I2 is
a solid at STP?
3. Molecules of Br2 have stronger intermolecular
forces than molecules of I2.
4. Molecules of I2 have stronger intermolecular forces
than molecules of Br2.
3
99. A neutron has a charge of
3. 0
4. -1
3 A neutron is a subatomic particle that has a charge
of 0.
Wrong Choices Explained:
(1) A proton and a positron each have a charge of +1.
(2) An alpha particle has a charge of +2.
(4) An electron has a charge of −1.
1. alpha particle
2. beta particle
2
100. Which particle has the least mass?
2 A beta particle is an electron and is the least
1
3. neutron
4. proton
massive of the particles named in this question.
1. each atom in the sample has 29 protons
2. atoms in the sample react with oxygen
1 An element is defined by its atomic number—the
number of protons in the nucleus of each atom. Refer
to the Periodic Table of the Elements. The atomic
number of copper (Cu) is 29.
1. charge of an electron
2. conductivity of an electron
101. A sample of matter must be copper if
3. the sample melts at 1768 K
4. the sample can conduct electricity
3
102. In the electron cloud model of the atom, an orbital is defined
as the most probable
3. location of an electron
4. mass of an electron
3 An orbital is defined as the region of space in which 1
103. The elements on the Periodic Table are arranged in order of
an electron is most probably located.
increasing
1. atomic number
3. number of isotopes
2. mass number
4. number of moles
1 The Periodic Table is arranged in order of
increasing atomic number because this arrangement
displays the repeating nature of physical and
chemical properties.
1. tantalum
2. rhenium
2 Use Reference Table S. Rhenium (element number
75), with a melting point of 3453 K, has a higher
melting point than any of the other elements listed in
the question.
1. energy, volume, and mass
2. energy, volume, and charge
2
104. Which element has the highest melting point?
3. osmium
4. hafnium
3
105. In a chemical reaction, there is conservation of
3. mass, charge, and energy
4. mass, charge, and volume
3 In all chemical reactions, mass, charge, and energy 4
106. At STP, both diamond and graphite are solids composed of
must be conserved.
carbon atoms. These solids have
1. the same crystal structure and the same properties 3. different crystal structures and the same properties
2. the same crystal structure and different properties 4. different crystal structures and different properties
1
4 Diamond and graphite are allotropes of the element 107. Given the balanced equation representing a reaction:
carbon. As such, they have different crystal structures
Cl2 → Cl + Cl
and different chemical and physical properties.
1. A bond is broken as energy is absorbed.
2. A bond is broken as energy is released.
1 Cl2 is a molecule of chlorine in which the two
chlorine atoms are joined by a single bond. When Cl2
is split into two Cl atoms, the single bond is broken.
The breaking of a bond always requires the
absorption of energy.
1. Cl atom
2. F atom
What occurs during this reaction?
3. A bond is formed as energy is absorbed.
4. A bond is formed as energy is released.
4
108. Which atom has the weakest attraction for the electrons in a
bond with an H atom?
3. O atom
4. S atom
electronegativity of the atom. The smaller the
electronegativity, the weaker the attraction. Use
Reference Table S. Of the choices given, choice (4),
S, has the smallest electronegativity.
1. ammonia
2. mercury
2 Elements cannot be broken down by a chemical
change. Of the choices given, only choice (2),
mercury, is an element.
Wrong Choices Explained:
(2), (3), (4) These substances are compounds. They
can be broken down by chemical change.
1. formation of covalent bonds
2. formation of ionic bonds
3 The total mass of the products of a nuclear fission
reaction is less than the total mass of the reactants.
The "missing" matter is converted to energy.
1. C-14
2. U-238
2
109. Which substance can not be broken down by a chemical
change?
3. propane
4. water
3
110. Energy is released during the fission of Pu-239 atoms as a
result of the
3. conversion of matter to energy
4. conversion of energy to matter
3
111. Which isotope is used to treat cancer?
3. Co-60
4. Pb-206
3 Radioactive isotopes have many uses in science,
medicine, and industry. The isotope Co-60 is widely
used to treat cancer by radiation.
Wrong Choices Explained:
(1) The isotope C-14 is used to determine the date of 2
once-living materials, and to trace the path of carbon 112. Which nuclide is listed with its half-life and decay mode?
in organic and biochemical reactions.
(2) The isotope U-238 is used to determine the age of
rocks and also to "breed" nuclear fuel.
(4) The isotope Pb-206 is not radioactive.
2
2 Use Reference Table N. Of the choices given, only 113. The accompanying table shows the number of subatomic
choice (2), N–16, 7.2 s, β-, lists both the correct half- particles in atom X and in atom Z.
life and correct decay mode for the given nuclide.
Atom X and atom Z are isotopes of the element
1. aluminum
2. carbon
3. magnesium
4. nitrogen
contained in each atom of the element, which is its
atomic number. Refer to the Periodic Table of the
Elements. The element carbon (C) has an atomic
number of 6.
1. Br and Cl
2. Br and F
4 The polarity of the bond between two atoms can be
estimated by determining the difference in the
electronegativities of the two atoms. Use Reference
Table S. Of the choices given, choice (4), I and F, has
the greatest difference in electronegativity. Therefore,
the bond between I and F is the most polar.
1. Group 1
2. Group 2
3 Use Reference Table E. The sulfate ion has a
charge of 2–(SO42–). Since 3 sulfate ions are present
in the compound, the total charge from sulfate must
be 6–. The 2 ions of element X must therefore have a
total charge of 6+. So, each ion of X must carry a
charge of 3+ (X3+). Refer to the Periodic Table of the
Elements. Of the choices given, only Group 13
contains metallic elements whose ions carry a charge
of 3+.
1. Al
2. K
4
114. The bond between which two atoms is most polar?
3. I and Cl
4. I and F
3
115. In the formula X2(SO4)3, the X represents a metal. This metal
could be located on the Periodic Table in
3. Group 13
4. Group 14
4
116. At STP, which element is solid, brittle, and a poor conductor
of electricity?
3. Ne
4. S
4 A solid element that is brittle and a poor conductor
of electricity is most likely a nonmetal. Refer to the
Periodic Table of the Elements. Of the choices given,
4
only choice (4), S, is a solid, nonmetallic element.
117. Which element forms an ionic compound when it reacts with
lithium?
Wrong Choices Explained:
(1), (2) Al and K are metallic elements.
(3) Ne is nonmetallic, but it is a gas at STP.
1. K
2. Fe
3. Kr
4. Br
4 Lithium (Li, atomic number 3) is a Group 1 element
that forms a positive ion. In order to form an ionic
2
compound, it must combine with a negative ion. Use 118. Given the accompanying formula representing a molecule:
the Periodic Table of the Elements. Of the choices
given, only choice (4), Br (atomic number 35), forms The molecule is
a negative ion.
1. symmetrical and polar
2. symmetrical and nonpolar
2 The formula represents the compound ethyne, a
linear molecule. Since the molecule is symmetrical,
the polarities of its individual bonds cancel each
other. So the molecule is nonpolar.
1. CO2
2. CH3OH
3. asymmetrical and polar
4. asymmetrical and nonpolar
4
119. Which compound has both ionic and covalent bonds?
3. NaI
4. Na2CO3
4 See Reference Table E. Generally, compounds that
contain polyatomic ions have both ionic and covalent
bonding. The covalent bonding exists within the
polyatomic ion. Only choice (4), Na2CO3, is an ionic
compound that joins Na+ to the polyatomic ion CO32–.
1. bromine
2. calcium
3 The energy needed to remove the most loosely held
electron from a gaseous atom in the ground state is
known as the first ionization energy. Use Reference
Table S. Of the choices given, choice (3), sodium
(atomic number 11), has the smallest first ionization
energy.
1. chemically combined in a fixed proportion
2. chemically combined in proportions that vary
1 A compound is defined as a substance in which the
elements present are chemically combined in a fixed
proportion. This definition allows a chemical formula
to be written for each compound.
1. phosphorus
2. nitrogen
3
120. Which element requires the least amount of energy to
remove the most loosely held electron from a gaseous atom in the
ground state?
3. sodium
4. silver
1
121. Every water molecule has two hydrogen atoms bonded to
one oxygen atom. This fact supports the concept that elements in
a compound are
3. physically mixed in a fixed proportion
4. physically mixed in proportions that vary
2
122. Which Group 15 element exists as diatomic molecules at
STP?
3. bismuth
4. arsenic
2 Seven common elements exist as diatomic
4
molecules: H2, O2, N2, F2, Cl2, Br2, and I2. Only N2 is 123. What is the total number of electrons shared in a double
located in Group 15.
covalent bond?
1. 1
3. 3
2. 2
4. 4
3
124. Given the balanced equation representing a reaction in the
accompanying diagram:
4 In a double covalent bond, two pairs or 4 electrons
are shared between two atoms.
Br2 + energy → Br + Br
1. Energy is released as bonds are broken.
2. Energy is released as bonds are formed.
3 Note that the energy term appears as a reactant.
This indicates that energy is absorbed by each Br 2
molecule. Note also that the product consists of 2 Br
atoms. This indicates that the single bond in each Br2
molecule has been broken.
1. methane
2. propanal
Which statement describes the energy change and bonds in this
reaction?
3. Energy is absorbed as bonds are broken.
4. Energy is absorbed as bonds are formed.
3
125. Which substance can not be broken down by a chemical
change?
3. tungsten
4. water
3 Tungsten (atomic number 74) is an element, which
cannot be broken down by a chemical change.
Wrong Choices Explained:
(1), (2), (4) Methane, propanal, and water are
compounds, which can all be broken down by
3
126. Which formula represents a mixture?
chemical changes.
1. C6H12O6(l)
2. C6H12O6(s)
3 A solution is a homogeneous mixture. The
designation LiCl(aq) represents an aqueous solution
of LiCl.
1. elements with identical boiling points
2. elements with different boiling points
4 Distillation is used to separate mixtures that contain
substances with different boiling points.
Hydrocarbons are compounds, not elements.
1. decay mode
2. bright-line spectrum
3. LiCl(aq)
4. LiCl(s)
4
127. Petroleum can be separated by distillation because the
hydrocarbons in petroleum are
3. compounds with identical boiling points
4. compounds with different boiling points
2
128. The isotopes K-37 and K-42 have the same
3. mass number for their atoms
4. total number of neutrons in their atoms
2 The isotopes K-37 and K-42 are isotopes of the
same element, potassium. Each element has a unique
bright-line spectrum. Therefore, K-37 and K-42 will
have the same bright-line spectrum.
Wrong Choices Explained:
(1) Use Reference Table N. The decay mode of K-37
is β+; the decay mode of K-42 is β-.
(3) The mass number of K-37 is 37, and the mass
number of K-42 is 42.
(4) An atom of K-37 has 18 neutrons in its nucleus,
while an atom of K-42 has 23 neutrons in its nucleus.
1. decomposition
2. neutralization
4
129. In which type of reaction is an atom of one element
converted to an atom of a different element?
3. saponification
4. transmutation
4 Transmutation is defined as the nuclear process in 2
which the nucleus of one element is transformed into 130. What is the total number of valence electrons in a calcium
the nucleus of another element.
atom in the ground state?
1. 8
3. 18
2. 2
4. 20
2 Valence electrons are those found in the outermost
shell of an atom of ion. Refer to the Periodic Table of
the Elements. The ground-state electron configuration
of calcium (Ca, atomic number 20) is 2–8–8–2. There
are 2 electrons in the outermost shell of this atom in
the ground state.
1. electrons and neutrons
2. electrons and protons
3
131. Which subatomic particles are located in the nucleus of an
He-4 atom?
3. neutrons and protons
4. neutrons, protons, and electrons
3 The nuclei of all atoms (with the exception of H–1) 1
132. In the late 1800s, experiments using cathode ray tubes led to
contain protons and neutrons.
the discovery of the
1. electron
3. positron
2. neutron
4. proton
1 The physicist J. J. Thomson used cathode rays to
identify the properties of the negative particles known 4
133. The atomic mass of titanium is 47.88 atomic mass units.
as electrons.
1. total mass of all the protons and neutrons in an
atom of Ti
2. total mass of all the protons, neutrons, and
electrons in an atom of Ti
4 The average atomic mass of an element is
calculated by determining the weighted average of all
of the element's naturally occurring isotopes. The
most abundant, naturally occurring isotopes have the
greatest effect on the value of the average atomic
mass.
1. Fe
2. Mg
2 Use Reference Table S. Of the choices given,
choice (2), Mg (atomic number 12), has the largest
atomic radius.
This atomic mass represents the
3. weighted average mass of the most abundant
isotope of Ti
4. weighted average mass of all the naturally
occurring isotopes of Ti
2
134. An atom of which element has the largest atomic radius?
3. Si
4. Zn