Chemistry: The Central Science, 12e (Brown et al.)
Chapter 12 Solids and Modern Materials
12.1 Multiple–Choice Questions
1) A solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n)
__________ solid.
A) ionic
B) molecular
C) metallic
D) covalent network
E) metallic and covalent network
2) Which of the following is not a type of solid?
A) ionic
B) molecular
C) supercritical
D) metallic
E) covalent-network
3) Crystalline solids differ from amorphous solids in that crystalline solids have __________.
A) appreciable intermolecular attractive forces
B) a long-range repeating pattern of atoms, molecules, or ions
C) atoms, molecules, or ions that are close together
D) much larger atoms, molecules, or ions
E) no orderly structure
4) The unit cell with all sides the same length and all angles equal to 90° that has lattice points only at
the corners is called __________.
A) monoclinic
B) body-centered cubic
C) primitive cubic
D) face-centered cubic
E) spherical cubic
5) Which one of the following cannot form a solid with a lattice based on the sodium chloride structure?
A) NaBr
B) LiF
C) RbI
D) CuO
E) CuCl2
6) Consider the following statements about crystalline solids:
(i) Molecules or atoms in molecular solids are held together via
intermolecular forces.
(ii) Metallic solids have atoms in the points of the crystal lattice.
(iii)Ionic solids have formula units in the point of the crystal lattice.
(iv) Atoms in covalent-network solids are connected via a network
of covalent bonds.
Which of the statements is false?
A) (i)
B) (ii)
C) (iii)
D) (iv)
E) none
7) The scattering of light waves upon passing through a narrow slit is called __________.
A) diffusion
B) grating
C) diffraction
D) adhesion
E) incidence
8) What fraction of the volume of each corner atom is actually within the volume of a face-centered
cubic unit cell?
A) 1
B) 1/2
C) 1/4
D) 1/8
E) 1/16
9) What portion of the volume of each atom or ion on the face of a unit cell is actually within the unit
cell?
A) 1/2
B) 1/4
C) 3/4
D) all of it
E) none of it
10) An alloy is a
A) heterogeneous mixture of two metals.
B) pure metal.
C) metallic material that is composed of two or more elements.
D) nonmetal with some properties of a metal.
E) a mineral containing two or more metals.
11) Steel is
A) an alloy of iron.
B) pure iron.
C) oxidized iron.
D) a mixture of iron and silver.
E) a liquid at room temperature.
12) Which one of the following is a property of most metals?
A) low melting point
B) brittleness
C) high electronegativity
D) thermal conductivity
E) acidic oxides
13) Which statement about steel is false?
A) It is a polymer.
B) It is an alloy of iron.
C) It can have different percentages of carbon.
D) It can be made so it resists rust.
E) none of the above
14) For a substitutional alloy to form, the two metals combined must have similar
A) ionization potential and electron affinity.
B) number of valance electrons and electronegativity.
C) reduction potential and size.
D) atomic radii and chemical bonding properties.
E) band gap and reactivity.
15) What is the typical effect of the addition of an interstitial element on the properties of a metal?
A) increase in malleability and corrosion resistance
B) increase in hardness and strength, decrease in ductility
C) decrease in melting point and increase in ductility
D) decrease in conductivity and increase in brittleness
E) increased surface luster
16) Heterogeneous alloys
A) have properties that depend on composition.
B) have properties that depend on the manner in which the melt is solidified.
C) have properties that depend on the manner in which the solid is formed.
D) All of the above are true.
17) Intermetallic compounds are examples of
A) homogeneous alloys.
B) heterogeneous alloys.
C) interstitial alloys.
D) solution alloys.
E) ionic compounds.
18) Which of the following is not an alloy?
A) brass
B) steel
C) sterling silver
D) dental amalgam
E) ceramic
19) Alloys generally differ from compounds in that
A) the former always contain some carbon.
B) the former always contain some iron.
C) the former always have semiconductor properties.
D) the atomic ratios of the constituent elements in the former are not fixed and may vary over a wide
range.
E) the former never contain a transition element.
20) Which element is typically not added to steel to modify its properties?
A) carbon
B) vanadium
C) chromium
D) nitrogen
E) nickel
21) Metallic solids do not exhibit __________.
A) excellent thermal conductivity
B) excellent electrical conductivity
C) variable hardness
D) extreme brittleness
E) variable melting point
22) Which property of metals cannot be explained with the electron-sea model?
A) shine
B) high thermal conductivity
C) high electric conductivity
D) malleability and ductility
E) trends in melting points
23) If the electronic structure of a solid substance consists of a valence band that is completely filled
with electrons and there is a large energy gap to the next set of orbitals, then this substance will be a(n)
__________.
A) alloy
B) insulator
C) conductor
D) semiconductor
E) nonmetal
24) CsCl crystallizes in a unit cell that contains a Cs+ ion at the center of a cube and a Cl– ion at each
corner. The unit cell of CsCl is __________.
A) close packed
B) body-centered cubic
C) face-centered cubic
D) amorphous
E) primitive cubic
25) NaCl crystallizes in a face-centered cubic cell. What is the total number of ions (Na+ ions and Cl–
ions) that lie within a unit cell of NaCl?
A) 2
B) 4
C) 8
D) 6
E) 5
26) An ionic solid, NaCl (s), dissolves in water because of the __________.
A) relatively low lattice energy due to small charges of Na+ and Cl– ions
B) simple face-centered cubic unit cell type it forms
C) 1:1 ratio of ions in the unit cell
D) strong coulombic interactions between oppositely charged ions
E) relatively low melting point
27) CsCl crystallizes in a unit cell that contains the Cs+ ion at the center of a cube that has a Cl– at each
corner. Each unit cell contains __________ Cs+ ions and __________ Cl–, ions, respectively.
A) 1 and 8
B) 2 and 1
C) 1 and 1
D) 2 and 2
E) 2 and 4
28) The process of doping can produce a __________ which can greatly __________ intrinsic
conductivity.
A) n-type semiconductor, increase
B) p-type semiconductor, decrease
C) non-metal, increase
D) non-metal, decrease
E) allotrope, diminish
7
29) The molecular-orbital model for Ge shows it to be
A) a conductor, because all the lower energy band orbitals are filled and the gap between the lower and
higher bands is large.
B) an insulator, because all the lower energy band orbitals are filled and the gap between the lower and
higher bands is large.
C) a semiconductor, because the gap between the filled lower and empty higher energy bands is
relatively small.
D) a semiconductor, because the gap between the filled lower and empty higher energy bands is large.
E) a conductor, because its lower energy band orbitals are only partially filled.
30) Inorganic compounds that are semiconductors have an average of __________ valence electrons.
A) 1
B) 2
C) 3
D) 4
E) 5
31) Of the following, only __________ is not a polymer.
A) cellulose
B) nylon
C) starch
D) protein
E) stainless steel
32) Which one of the following is an addition polymer with the same structure as polyethylene except
that one hydrogen on every other carbon is replaced by a benzene ring?
A) polyvinyl chloride
B) polypropylene
C) polystyrene
D) polyurethane
E) nylon 6, 6
33) Which of the following is not a natural polymer?
A) silk
B) starch
C) protein
D) cellulose
E) nylon
34) The empirical formula of an addition polymer __________.
8
A) is the same as that of the monomer from which it is formed except that 2 H and 1 O have been added
B) is the same as that of the monomer from which it is formed except that 2 H and 1 O have been
subtracted
C) is the same as that of the monomer from which it is formed
D) is the same as that of the monomer from which it is formed except that 2 H and 1 C have been added
E) is the same as that of the monomer from which it is formed except that 2 H and 1 C have been
subtracted
35) Of the following, only __________ is an addition polymer.
A) polyethylene terephthalate
B) polystyrene
C) polyurethane
D) polycarbonate
E) Nylon 6,6
36) An elastomer will fail to regain its original dimensions following a distortion beyond its
__________.
A) glass transition
B) phase boundary
C) London force
D) crystallinity
E) elastic limit
37) As a polymer becomes more crystalline, __________.
A) its melting point decreases
B) its density decreases
C) its stiffness decreases
D) its yield stress decreases
E) None of the above is correct.
38) The monomer that is polymerized to make natural rubber is __________.
A) melamine
B) formaldehyde
C) ethylene
D) isoprene
E) adipic acid
39) Natural rubber is too soft and chemically reactive for practical applications. Vulcanization of natural
rubber entails __________.
A) conversion of an addition polymer to a condensation polymer
B) conversion of a condensation polymer to an addition polymer
C) increasing the average molecular weight of a condensation polymer
D) decreasing the average molecular weight of an addition polymer
E) crosslinking reactive polymer chains with sulfur atoms
40) The formation of a condensation polymer generally involves __________.
A) the addition of a plasticizer
B) the mixing of sulfur with an addition polymer
C) the elimination of a small molecule
D) the vaporization of a plasticizer
E) the formation of significant crosslinking
41) Which of the following is not classified as a nanomaterial?
A) isoprene
B) buckminsterfullerene
C) carbon nanotubes
D) graphene
E) All of the above are classified as nanomaterials
42) The properties of graphene include __________.
A) high strength
B) low thermal conductivity
C) a zero energy gap
D) a and c
E) a, b and c
12.2 Bimodal Questions
1) __________ solids consist of atoms or molecules held together by dipole-dipole forces, London
dispersion forces, and/or hydrogen bonds.
A) Ionic
B) Molecular
C) Metallic
D) Covalent-network
E) Metallic and covalent-network
2) Gallium crystallizes in a primitive cubic unit cell. The length of the unit cell edge is 3.70 Å.
The radius of a Ga atom is __________ Å.
A) 7.40
B) 3.70
C) 1.85
D) 0.930
E) Insufficient data is given.
3) Potassium metal crystallizes in a body-centered cubic structure with a unit cell edge length of 5.31 Å.
The radius of a potassium atom is __________ Å.
A) 1.33
B) 1.88
C) 2.30
D) 2.66
E) 5.31
4) 18 karat gold contains __________% gold.
A) 18
B) 25
C) 89
D) 75
E) 1.0 x 102
5) 12 karat gold contains __________% gold.
A) 12
B) 25
C) 5.0 x 101
D) 75
E) 1.0 x 102
6) 24 karat gold contains __________% gold.
A) 24
B) 25
C) 5.0 x 101
D) 75
E) 1.00 x 102
7) 6.0 karat gold contains __________% gold.
A) 6.0
B) 25
C) 5.0 x 101
D) 75
E) 1.0 x 102
8) The transition metals in group __________ have the highest melting points.
A) 4B
B) 3B
C) 6B
D) 8B
E) 2B
9) The class of semiconductors, known as elemental, has special features. These are __________.
A) band gap and individual element valence electrons
B) periodical table grouping and diamond crystal structure
C) tetrahedral coordination geometry and sp2 hybrid orbitals
D) overlapping hybrid orbitals and filed conduction bands
E) none of the above
10) Blue LEDs are usually made of __________.
A) GaAs
B) GaP
C) GaO
D) GaS
E) GaN
11) A sample of natural rubber (200.0 g) is vulcanized, with the complete consumption of 4.8 g of
sulfur. Natural rubber is a polymer of isoprene (C5H8). Four sulfur atoms are used in each crosslink
connection. What percent of the isoprene units will be crosslinked?
A) 7.6
B) 5.1
C) 2.5
D) 9.4
E) 1.3
12) A category __________ plastic container will generally be the most easily recycled.
A) 1
B) 2
C) 3
D) 4
E) 22
13) When the size of a semiconductor particle or crystal __________, the band gap energy __________.
A) decreases, decreases
B) decreases, remains the same
C) increases, increases
D) decreases, increases
E) decreases, goes to zero
12.3 Short Answer Questions
1) When lattice points occur only at the corners of a unit cell, the cell is called __________.
2) When lattice points occur at the corners and at the center of a unit cell, the cell is called __________.
3) When lattice points occur at the center of each face, as well as each corner of a unit cell, the cell is
called __________.
4) A material that contains more than one element and has the characteristic properties of metals is
called a (an) __________.
5) How many atoms are contained in a face-centered cubic unit cell?
6) Chromium crystallizes in a body-centered cubic unit cell. There are __________ chromium atoms per
unit cell.
7) What two metals are alloyed to produce sterling silver?
8) Semiconductors are less conductive than metals because of __________ gap.
9) __________ are materials characterized by an energy gap between a filled valence band and an empty
conduction band.
10) The process of adding controlled amounts of impurity atoms to a material is known as __________.
11) The dopant atoms in an n-type semiconductor have __________ electrons than the host material.
12) Semiconductor particles with diameters of 1-10 nm are called __________.
13) Write the chemical formulas for both polyethylene and the monomer from which it is formed.
14) Nylon is formed by the reaction of a __________ with a __________.
15) Polymers formed from two different monomers are called __________.
16) In addition to differences in their average molecular mass, HDPE and LDPE differ in their degree of
__________ and their __________ of the chains.
17) __________ are solid-state materials that can be made either semiconducting or metallic without any
doping.
12.4 True/False Questions
1) The type of solid that is characterized by low melting point, softness, and low electrical conduction is
a covalent-network solid.
2) Many metals are ductile, which means that they can be hammered into thin sheets.
3) Silicon technology is based on the fact that silicon oxide is a chemically stable conductor.
4) Polyethylene is formed by a condensation reaction.
5) Vulcanization involves heating rubber with sulfur dioxide to produce a thermosetting polymer.
6) A plasticizer makes a polymer more pliable by reducing the interactions between polymer chains.