Chemistry Test.2
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. Electrons involved in bonding between atoms are
a. valence electrons.
b. inside the nucleus.
c. closest to the nucleus.
d. positively charged.
2. Each family in the periodic table has its own characteristic properties based on the number of
a. neutrons.
b. valence electrons.
c. protons.
d. ions.
3. What is the greatest number of valence electrons an atom can have?
a. 2
b. 3
c. 8
d. 12
4. If atoms of a halogen nonmetal (Group 17) gain one electron, the atoms then have
a. no valence electrons.
b. 7 valence electrons.
c. 8 valence electrons.
d. 17 valence electrons.
5. When an atom loses an electron, it becomes a
a. positive ion.
b. negative ion.
c. neutral ion.
d. neutral atom.
6. An ionic bond is the attraction between
a. similarly charged ions.
b. oppositely charged ions.
c. neutral ions.
d. neutral atoms.
7. Ions that are made of more than one atom are examples of
a. polyatomic ions.
b. negative ions.
c. positive ions.
d. neutral ions.
8. Ionic compounds are electrically
a. charged.
b. positive.
c. negative.
d. neutral.
____
9. Magnesium bromide is an ionic compound with the chemical formula MgBr2. What does the “2”
tell you?
a. Bromide has a 2 charge.
b. There are two magnesium ions to every bromide ion.
c. There are two bromide ions for every magnesium ion.
d. Bromide has a 2+ charge.
10. What is the chemical name for the compound with the formula Na2S?
a. sodium fluoride
b. magnesium sulfide
c. lithium oxide
d. sodium sulfide
11. In the chemical formula for an ionic compound, which item is written first?
a. positive ion
b. negative ion
c. subscript
d. charge
12. Which of the following is a characteristic property of ionic compounds?
a. They have low melting points.
b. They have low boiling points.
c. They form hard, brittle crystals with characteristic shapes.
d. They contain no charged particles.
13. In what form can an ionic compound conduct electricity?
a. as a solid
b. when dissolved in water
c. as a crystal
d. when warmed slightly
14. A chemical bond formed when two atoms share electrons is called a(n)
a. ionic bond.
b. covalent bond.
c. polyatomic bond.
d. crystal bond.
15. What is a double bond?
a. a bond between two atoms
b. one pair of electrons shared between two atoms
c. two pairs of electrons shared between two atoms
d. two pairs of electrons shared between four atoms
16. Which is a property shared by most molecular compounds?
a. high boiling point
b. high melting point
c. low melting point
d. nonpolar bonds
17. Molecular compounds do not conduct electricity because they
a. break up into ions.
b. do not break up into ions.
c. do not dissolve in water.

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18.
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19.
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20.
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21.
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22.
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23.
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24.
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25.
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26.
d. have high melting points.
A covalent bond in which electrons are shared unequally is
a. polar.
b. a double bond.
c. ionic.
d. polyatomic.
Molecules that contain two polar bonds are
a. ionic.
b. always polar.
c. always nonpolar.
d. sometimes polar.
Water is polar and oil is nonpolar. What happens when the two liquids are poured into the same
container?
a. Both liquids become nonpolar.
b. A gas is produced.
c. The liquids mix well.
d. The liquids do not mix.
A mixture that is made of two or more elements—one that is a metal—that has the properties of
metal is a(n)
a. polymer.
b. monomer.
c. alloy.
d. ceramic.
What is an advantage that alloys might have over many pure metals?
a. Alloys occur naturally.
b. Alloys resist rust.
c. Alloys are weaker.
d. Alloys can bend easily.
Steel is an alloy of one or more elements combined with
a. copper.
b. gold.
c. iron.
d. lead.
Which of the following properties is NOT characteristic of steel?
a. does not readily react with water
b. resistant to rust
c. strength
d. reacts readily with air
Brass and steel are examples of
a. alloys.
b. elements.
c. pure metals.
d. valence electrons.
What strong alloy, containing carbon, iron, and another metal like chromium or nickel, is used to
make construction equipment, bicycle frames, and train rails?
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27.
____
28.
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29.
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30.
a. brass
b. gold alloy
c. silver
d. steel
Which of the following best describes a metal crystal?
a. metal atoms held together by covalent bonds
b. metal atoms held together by ionic bonds
c. positive metal ions surrounded by freely moving valence electrons
d. neutral metal atoms surrounded by freely moving valence electrons
The attraction between a positive metal ion and the electrons surrounding it is a(n)
a. chemical bond.
b. covalent bond.
c. ionic bond.
d. metallic bond.
Which of the following terms means that metals can be rolled into thin sheets, as in aluminum foil,
or beaten into complex shapes?
a. polar
b. alloy
c. ductile
d. malleable
Which of the following terms means that metals can be pulled into thin strands or wires?
a. polar
b. alloy
c. ductile
d. malleable
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the
statement true.
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31. The valence electrons are those electrons most tightly held by the atom.
_________________________
____
32. Each family in the periodic table has its own characteristic properties based upon its number of
valence electrons. _________________________
____
33. When an atom gains an electron it becomes a positive ion. _________________________
____
34. The attraction between a positive ion and a negative ion results in a covalent bond.
_________________________
____
35. Orderly crystal shapes, high melting points, and electrical conductivity when dissolved in water are
properties of ionic compounds. _________________________
____
36. When electrons are transferred between two atoms, a covalent bond is formed.
_________________________
____
37. Low melting points and lack of electrical conductivity are properties of molecular compounds.
_________________________
____
38. A nonpolar bond is formed when two atoms share electrons unequally.
_________________________
____
39. In every alloy, at least one of the components is a(n) metal. _________________________
____
40. Steel is an alloy of iron with carbon, nickel, and other elements. _________________________
Completion
Complete each statement.
41. Chemical bonds form when valence electrons are ____________________ between atoms.
42. A neutral atom never has more than ____________________ valence electrons.
43. In the periodic table, atoms are arranged from left to right and from top to bottom in order of
increasing _________________________.
44. With the exception of helium, Group 18 elements usually have ______________ valence
electrons, so they do not usually react with other elements.
45. Elements in Group 17 (the halogens) are the ____________________ reactive nonmetals.
46. Nitrate (NO3–), ammonium (NH4+), and carbonate (CO32–) are examples of
____________________ ions.
47. When ions having a positive charge form bonds with ions having a negative charge, the charge on
the resulting compound is ____________________.
48. Elements in Group 1 lose one electron to form ions with a(n) ____________________ charge.
49. When an ionic compound forms, the total number of positive charges and the total number of
negative charges must be ____________________.
50. Ionic compounds that dissolve in water conduct electricity because they break into
____________________ that move freely.
51. Ionic compounds have ____________ melting points because a lot of energy is needed to break the
bonds between the ions.
52. Bonds that form between two nonmetal atoms usually are ____________________ bonds.
53. In a double covalent bond, ____________________ electrons are shared between two atoms.
54. Molecular compounds that dissolve in water do not conduct electricity because no
_________________________ are present.
55. A(n) ____________________ compound is a compound that consists of molecules made of atoms
that are covalently bonded.
56. Fluorine (F2) is a(n) ____________________ molecule because the valence electrons are shared
equally between the two fluorine atoms.
57. Because the electrons in a molecule of hydrogen fluoride (HF) are more strongly pulled toward the
fluorine atom, the molecule is ____________________.
58. Many ____________________ are made by melting metals and mixing them together in carefully
measured amounts.
59. A metal crystal consists of positively charged metal ions embedded in a “sea” of freely moving
_________________________ electrons.
60. Solid metals are good conductors of heat and ____________________.
Short Answer
Use the diagram to answer each question.
61. List three elements from the group containing the most reactive nonmetals.
62. In each period, how does the number of electrons in each kind of atom change from left to right
between Groups 1 and 2? Explain how you know.
63. In an electron dot diagram of aluminum (Al), how many dots should be drawn around the
element’s symbol? Why?
64. Which group of elements loses electrons most easily?
65. Which group contains elements with two valence electrons?
66. How many atoms of a Group 17 element would be needed to react with one atom of a Group 2
element? Explain.
Use the table below to answer the following questions.
Name
Lithium
____?___
Calcium
Chloride
___?____
Carbonate
Ions and Their Charges
Charge
Symbol or Formula
_?_
Li+
1+
Na+
2+
___?__
1–
___?__
1–
2–
NO3
___?___

67. What is the charge for a lithium ion?
68. What is the symbol for a calcium ion?
69. What is the name of the ion with the chemical formula NO3–?
70. Which of these ions are polyatomic? Explain.
71. What is the chemical formula of the compound that forms when sodium and chloride combine?
72. What is the chemical name for CaCO3?
Essay
73. How do valence electrons relate to the chemical reactions of an element?
74. Explain what makes the Group 1 elements the most reactive metals.
75. Compare a covalent bond and an ionic bond.
76. Describe properties that would help you to distinguish an ionic compound from a molecular
compound.
77. Explain what is meant by the term “polar bond.”
78. Why are alloys often more useful than pure metals?
79. Explain why metals are such good conductors of heat and electricity.
Chemistry Test.2
Answer Section
MULTIPLE CHOICE
1. ANS: A
PTS: 1
DIF: L2
OBJ: CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
STA: S 8.3.a
BLM: comprehension
2. ANS: B
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.3.a
BLM: comprehension
3. ANS: C
PTS: 1
DIF: L1
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.3.a
BLM: knowledge
4. ANS: C
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: application
5. ANS: A
PTS: 1
DIF: L1
OBJ: CaPS.5.2.1 Explain how ions form bonds.
STA: S 8.3.a
BLM: knowledge
6. ANS: B
PTS: 1
DIF: L1
OBJ: CaPS.5.2.1 Explain how ions form bonds.
STA: S 8.3.c
BLM: knowledge
7. ANS: A
PTS: 1
DIF: L1
OBJ: CaPS.5.2.1 Explain how ions form bonds.
STA: S 8.3.b
BLM: knowledge
8. ANS: D
PTS: 1
DIF: L2
OBJ: CaPS.5.2.1 Explain how ions form bonds.
STA: S 8.3.b
BLM: comprehension
9. ANS: C
PTS: 1
DIF: L2
OBJ: CaPS.5.2.2 Explain how the formulas and names of ionic compounds are written.
STA: S 8.3.b
BLM: application
10. ANS: D
PTS: 1
DIF: L2
OBJ: CaPS.5.2.2 Explain how the formulas and names of ionic compounds are written.
STA: S 8.3.b
BLM: application
11. ANS: A
PTS: 1
DIF: L1
OBJ: CaPS.5.2.2 Explain how the formulas and names of ionic compounds are written.
STA: S 8.3.b
BLM: knowledge
12. ANS: C
PTS: 1
DIF: L2
OBJ: CaPS.5.2.3 Identify the properties of ionic compounds.
STA: S 8.7.c
BLM: comprehension
13. ANS: B
PTS: 1
DIF: L1
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
OBJ:
BLM:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
OBJ:
STA:
ANS:
CaPS.5.2.3 Identify the properties of ionic compounds.
STA: S 8.3.b
knowledge
B
PTS: 1
DIF: L1
CaPS.5.3.1 State what holds covalently bonded atoms together.
S 8.3.b
BLM: knowledge
C
PTS: 1
DIF: L2
CaPS.5.3.1 State what holds covalently bonded atoms together.
S 8.3.b
BLM: comprehension
C
PTS: 1
DIF: L2
CaPS.5.3.2 Identify the properties of molecular compounds.
S 8.3.b | S 8.7.c
BLM: comprehension
B
PTS: 1
DIF: L2
CaPS.5.3.2 Identify the properties of molecular compounds.
S 8.3.b | S 8.7.c
BLM: application
A
PTS: 1
DIF: L1
CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
S 8.3.b
BLM: knowledge
D
PTS: 1
DIF: L2
CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
S 8.3
BLM: comprehension
D
PTS: 1
DIF: L2
CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
S 8.3.b | S 8.7.c
BLM: application
C
PTS: 1
DIF: L1
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: knowledge
B
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: application
C
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: comprehension
D
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: application
A
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: application
D
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: application
C
PTS: 1
DIF: L2
CaPS.5.4.2 Describe how metal atoms are bonded in solid metal.
S 8.3.c
BLM: comprehension
D
PTS: 1
DIF: L1
OBJ:
STA:
29. ANS:
OBJ:
STA:
30. ANS:
OBJ:
STA:
CaPS.5.4.2 Describe how metal atoms are bonded in solid metal.
S 8.3.a | S 8.3.b
BLM: knowledge
D
PTS: 1
DIF: L1
CaPS.5.4.3 Explain how metallic bonding results in useful properties of metals.
S 8.7.c
BLM: knowledge
C
PTS: 1
DIF: L1
CaPS.5.4.3 Explain how metallic bonding results in useful properties of metals.
S 8.7.c
BLM: knowledge
MODIFIED TRUE/FALSE
31. ANS: F, loosely
PTS:
OBJ:
STA:
32. ANS:
OBJ:
STA:
33. ANS:
1
DIF: L1
CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
S 8.3.a
BLM: knowledge
T
PTS: 1
DIF: L2
CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
S 8.7.a
BLM: comprehension
F
negative
PTS: 1
STA: S 8.3.b
34. ANS: F, an ionic
DIF: L2
OBJ: CaPS.5.2.1 Explain how ions form bonds.
BLM: comprehension
PTS:
STA:
35. ANS:
OBJ:
BLM:
36. ANS:
1
DIF: L1
OBJ: CaPS.5.2.1 Explain how ions form bonds.
S 8.3.b
BLM: knowledge
T
PTS: 1
DIF: L2
CaPS.5.2.3 Identify the properties of ionic compounds.
STA: S 8.3.c | S 8.7.c
comprehension
F, shared
PTS:
OBJ:
STA:
37. ANS:
OBJ:
STA:
38. ANS:
1
DIF: L2
CaPS.5.3.1 State what holds covalently bonded atoms together.
S 8.3.b
BLM: comprehension
T
PTS: 1
DIF:
CaPS.5.3.2 Identify the properties of molecular compounds.
S 8.7.c
BLM: comprehension
F, polar
L2
PTS: 1
DIF: L1
OBJ: CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
STA: S 8.3.b
BLM: knowledge
39. ANS:
OBJ:
STA:
40. ANS:
OBJ:
STA:
T
PTS: 1
DIF: L1
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.a
BLM: knowledge
T
PTS: 1
DIF: L2
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: application
COMPLETION
41. ANS:
transferred
shared
PTS:
OBJ:
STA:
42. ANS:
1
DIF: L2
CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
S 8.3.b
BLM: comprehension
eight
PTS:
OBJ:
STA:
43. ANS:
1
DIF: L2
CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
S 8.3.a
BLM: comprehension
atomic number
PTS: 1
DIF: L1
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.b
BLM: knowledge
44. ANS: eight
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: comprehension
45. ANS: most
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: comprehension
46. ANS: polyatomic
PTS: 1
DIF:
STA: S 8.3.c | S 8.3.f
47. ANS: zero
L2
OBJ: CaPS.5.2.1 Explain how ions form bonds.
BLM: application
PTS: 1
STA: S 8.3.b
48. ANS:
1+
1 positive
DIF: L2
BLM: application
PTS: 1
DIF:
STA: S 8.3.b | S 8.7.a
49. ANS: equal
PTS: 1
STA: S 8.3.b
50. ANS: ions
L2
OBJ: CaPS.5.2.1 Explain how ions form bonds.
OBJ: CaPS.5.2.1 Explain how ions form bonds.
BLM: application
DIF: L2
OBJ: CaPS.5.2.1 Explain how ions form bonds.
BLM: comprehension
PTS:
OBJ:
BLM:
51. ANS:
1
DIF: L2
CaPS.5.2.3 Identify the properties of ionic compounds.
comprehension
high
PTS:
OBJ:
BLM:
52. ANS:
1
DIF: L2
CaPS.5.2.3 Identify the properties of ionic compounds.
comprehension
covalent
STA: S 8.3.b
STA: S 8.3.b
PTS: 1
DIF: L2
OBJ: CaPS.5.3.1 State what holds covalently bonded atoms together.
STA: S 8.3.b
BLM: comprehension
53. ANS:
four
two pairs of
PTS: 1
DIF: L2
OBJ: CaPS.5.3.1 State what holds covalently bonded atoms together.
STA: S 8.3.b
BLM: application
54. ANS:
charged particles
charged ions
PTS:
OBJ:
STA:
55. ANS:
1
DIF: L2
CaPS.5.3.2 Identify the properties of molecular compounds.
S 8.3.b
BLM: comprehension
molecular
PTS: 1
DIF: L2
OBJ: CaPS.5.3.2 Identify the properties of molecular compounds.
STA: S 8.3.b
BLM: comprehension
56. ANS: nonpolar
PTS:
OBJ:
STA:
57. ANS:
1
DIF: L2
CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
S 8.7.c
BLM: application
polar
PTS:
OBJ:
STA:
58. ANS:
1
DIF: L3
CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
S 8.7.c
BLM: application
alloys
PTS:
OBJ:
STA:
59. ANS:
1
DIF: L1
CaPS.5.4.1 Explain how the properties of metals and alloys compare.
S 8.7.c
BLM: knowledge
valence
PTS:
OBJ:
STA:
60. ANS:
1
DIF: L1
CaPS.5.4.2 Describe how metal atoms are bonded in solid metal.
S 8.3.b
BLM: knowledge
electricity
PTS: 1
DIF: L2
OBJ: CaPS.5.4.3 Explain how metallic bonding results in useful properties of metals.
STA: S 8.7.c
BLM: comprehension
SHORT ANSWER
61. ANS:
Accept any three elements from Group 17: fluorine (F), chlorine (Cl), bromine (Br), iodine (I),
astatine (At).
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: analysis
62. ANS:
From Group 1 to Group 2, the number of electrons in each kind of atom increases by one in each
period. This is the case because the number of protons (atomic number) increases by one from
Group 1 to Group 2, and atoms have equal numbers of electrons and protons.
PTS: 1
DIF: L3
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: analysis
63. ANS:
Three. Elements in Group 13 have 3 valence electrons.
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.3.a
BLM: application
64. ANS:
Group 1
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: analysis
65. ANS:
Group 2
PTS: 1
DIF: L2
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: analysis
66. ANS:
Two. Atoms of elements in Group 17 form ions with a charge of 1–, and atoms of elements in
Group 2 form ions with a charge of 2+. It would take two ions of a Group 17 element to balance
the charge of one ion of a Group 2 element.
PTS: 1
STA: S 8.7.a
67. ANS:
1+
DIF: L3
BLM: synthesis
OBJ: CaPS.5.2.1 Explain how ions form bonds.
PTS: 1
STA: S 8.3.a
68. ANS:
Ca2+
DIF: L2
BLM: analysis
OBJ: CaPS.5.2.1 Explain how ions form bonds.
PTS: 1
STA: S 8.3.a
69. ANS:
Nitrate
DIF: L2
BLM: analysis
OBJ: CaPS.5.2.1 Explain how ions form bonds.
PTS: 1
STA: S 8.3.f
70. ANS:
DIF: L3
BLM: analysis
OBJ: CaPS.5.2.1 Explain how ions form bonds.
Nitrate (NO3–) and carbonate (CO32–) are polyatomic ions, because they are made of more than
one atom.
PTS: 1
STA: S 8.3.f
71. ANS:
NaCl
DIF: L3
BLM: analysis
OBJ: CaPS.5.2.1 Explain how ions form bonds.
PTS: 1
DIF: L2
OBJ: CaPS.5.2.2 Explain how the formulas and names of ionic compounds are written.
STA: S 8.3.f
BLM: analysis
72. ANS:
calcium carbonate
PTS: 1
DIF: L3
OBJ: CaPS.5.2.2 Explain how the formulas and names of ionic compounds are written.
STA: S 8.3.f
BLM: analysis
ESSAY
73. ANS:
Valence electrons are the electrons that are most loosely held by the atom and the ones that are
involved in chemical reactions. Chemical reactions occur whenever valence electrons are shared or
transferred between atoms. The number of valence electrons determines how these reactions take
place and what kind of bonds atoms can form.
PTS: 1
DIF: L3
OBJ: CaPS.5.1.1 Explain how the reactivity of elements is related to valence electrons in atoms.
STA: S 8.3.a
BLM: synthesis
74. ANS:
Atoms of Group 1 elements each have a single valence electron. These atoms easily lose their
valence electron, reacting with other elements that can gain electrons, and therefore becoming
more chemically stable. The easy loss of the one valence electron makes the Group 1 elements
more reactive than metals that must lose two or three electrons in reactions.
PTS: 1
DIF: L3
OBJ: CaPS.5.1.2 State what the periodic table tells you about atoms and the properties of
elements.
STA: S 8.7.a
BLM: synthesis
75. ANS:
A covalent bond is formed when two atoms share valence electrons. Neither atom loses electrons
or takes electrons from the other. No charged particles form. In an ionic bond, one or more
electrons are transferred from one atom to another. Atoms that lose electrons become positively
charged ions, and atoms that gain electrons become negatively charged ions. These oppositely
charged particles then attract each other.
PTS: 1
DIF: L2
OBJ: CaPS.5.2.1 Explain how ions form bonds. | CaPS.5.3.1 State what holds covalently bonded
atoms together.
STA: S 8.3.b
BLM: analysis
76. ANS:
Ionic compounds have high melting points and high boiling points compared to molecular
compounds. Ionic compounds that are dissolved in water or melted will conduct electricity.
Molecular compounds do not conduct electricity in either case.
PTS: 1
DIF: L2
OBJ: CaPS.5.2.3 Identify the properties of ionic compounds. | CaPS.5.3.2 Identify the properties
of molecular compounds.
STA: S 8.3.b | S 8.7.c
BLM: analysis
77. ANS:
When two atoms form a covalent bond, electrons are shared between them. If the atoms are
different, one atom may pull more strongly on the shared electrons so that the electrons are shared
unequally. This difference results in a bond that is slightly negative at one end and slightly positive
at the other end. This unequal sharing of electrons is known as a polar bond.
PTS: 1
DIF: L2
OBJ: CaPS.5.3.3 Explain how unequal sharing of electrons occurs and how it affects molecules.
STA: S 8.3.b
BLM: comprehension
78. ANS:
Alloys are usually stronger, harder, and more resistant to chemical reactions than pure metals.
However, alloys still have metallic properties, such as the ability to conduct heat and electricity.
The properties of alloys often make them more useful than pure metals in tools, machines, and
other items.
PTS: 1
DIF: L2
OBJ: CaPS.5.4.1 Explain how the properties of metals and alloys compare.
STA: S 8.7.c
BLM: comprehension
79. ANS:
A metal crystal consists of positively charged metal ions embedded in a “sea” of loosely held
valence electrons that can move around easily. Heat travels through materials as the increased
motion of the particles in the hotter parts of the material is passed along to the particles in the
cooler parts. In a metal, since particles are easily set into motion, heat is easily transferred, or
conducted. The same is true for the conduction of electricity. Electricity can flow when charged
particles, like electrons, are free to move. Since the electrons in a metal crystal can move freely
among the atoms, electricity is easily conducted.
PTS: 1
DIF: L3
OBJ: CaPS.5.4.3 Explain how metallic bonding results in useful properties of metals.
STA: S 8.7.c
BLM: synthesis