Deck 12: Solids: Crystals, Alloys, and Polymers

Question 1

Which of the following is true regarding the attractive force that holds sodium chloride in the solid state?
I.It is electrostatic.
II.It is termed ionic bonding.
III.It depends on the distance between the sodium and chloride.
IV.It only operates between adjacent sodium and chloride ions.

A)I and II only
B)II and III only
C)I, II, and III only
D)II and IV only
E)I-IV are all true statements.

Answer 1

I, II, and III only

Question 2

Quartz, a form of SiO₂, which contains an ordered array of neutral, covalently bonded nonmetal units, is an example of ________

A)a molecular solid.
B)a metallic solid.
C)an alloy.
D)an ionic solid.
E)an amorphous solid.

Answer 2

a molecular solid.

Question 3

A cubic closest-packed structure has hexagonally arranged layers of atoms stacking in the series ________

A)ababab
B)abcabcabc.
C)abcbabcbabcba.
D)abacabacaba.
E)aaaaaa.

Answer 3

abcabcabc.

Question 4

At a historic Civil War battleground, a stack of cannonballs looked like the picture below on the far left. Removing the top cannonball resulted in the middle view, and removing the next layer resulted in the view on the right. What sort of packing was used in stacking the cannonballs?

A)cannonball closest-packed
B)hexagonal closest-packed
C)cubic closest-packed
D)random-packed
E)body-centered closest-packed

Question 5

Which of the following contribute to the arrangement of ions in the unit cells of an ionic solid?
I.the empirical formula
II.the relative radii of the ions
III.the shape of polyatomic ions

A)I and II only
B)II and III only
C)I and III only
D)I only
E)I, II, and III

Question 6

What type of crystal structure produces an aaaaaa layering pattern?

A)hexagonal
B)face-centered cubic
C)simple cubic
D)body-centered cubic
E)hexagonal or body-centered cubic

Question 7

What type of crystal structure can produce an ababab layering pattern?

A)hexagonal
B)face-centered cubic
C)simple cubic
D)body-centered cubic
E)hexagonal or body-centered cubic

Question 8

Which statement A-D does not describe a simple cubic unit cell?

A)It results from square packing of atoms in layers.
B)The atoms lie at the corners of a cube.
C)Each atom has 6 nearest neighbors.
D)The stacking pattern can be represented by aaaa.
E)Statements A-D all correctly describe a simple cubic unit cell.

Question 9

In the sodium chloride unit cell, the chloride ions form a cube in which each side is arranged like the following figure. The circles represent the positions of the chloride ions on one square face of the cube. All the other faces are the same. What is the name of this unit cell?

A)simple cubic
B)chloride-centered cubic
C)face-centered cubic
D)x-face cubic
E)body-centered cubic

Question 10

Which is not true about a crystallographic unit cell?

A)It repeats throughout a crystalline structure in three dimensions.
B)It fills all the space in the crystalline lattice.
C)Its dimensions can be measured with X-rays.
D)It has corners with 90° angles.
E)It represents the smallest repeating unit in the crystal.

Question 11

The cubic closest-packed crystal structure has a ________ layering pattern that produces a ________ unit cell.

A)ababab; hexagonal
B)ababab; face-centered cubic
C)abcabcabc; hexagonal
D)abcabcabc; face-centered cubic
E)abcabcabc; body-centered cubic

Question 12

The closest-packing of spheres (such as oranges, cannonballs, or atoms) has the spheres ________

A)arranged in layers with each sphere surrounded by 4 other spheres in the layer.
B)arranged in layers with each sphere surrounded by 3 other spheres in the layer.
C)arranged in a square pattern with a sphere at each corner and one in the center of the square.
D)arranged in a square pattern with a sphere at each corner of the square.
E)arranged in layers with each sphere surrounded by 6 other spheres in the layer.

Question 13

What type of packing best describes the layering pattern shown below?

A)body-centered closest-packed
B)hexagonal closest-packed
C)random-packed
D)cubic closest-packed
E)cubic packing

Question 14

Ionic solids have ________ melting points, and are ________.

A)high; malleable
B)high; brittle
C)low; malleable
D)low; brittle
E)high; soft

Question 15

Identify the solid that has a high melting point, is hard and brittle, and conducts electricity when liquefied.

A)a network covalent solid
B)a metal
C)a covalent network
D)an ionic solid
E)an amorphous solid

Question 16

Which type of solid is held together by relatively weak dispersion forces?

A)ionic solid
B)metal
C)molecular solid
D)ceramic
E)semiconductor

Question 17

The face-centered cubic structure is also known as ________

A)cubic closest-packed.
B)hexagonal closest-packed.
C)square closest-packed.
D)spherical closest-packed.
E)none of the above, as it is not a closest-packed pattern.

Question 18

A hexagonal closest-packed structure has hexagonally arranged layers of atoms stacking in the series ________

A)ababab
B)abcabcabc.
C)abcbabcbabcba.
D)abacabacaba.
E)aaaaaa.

Question 19

The two types of closest-packed lattices are ________

A)cubic closest-packed and face-centered cubic.
B)cubic closest-packed and hexagonal closest-packed.
C)cubic closest-packed and random closest-packed.
D)cubic closest-packed and pyramidal closest-packed.
E)simple cubic and hexagonal closest-packed.

Question 20

Pure solid metals ________

A)do not crystallize.
B)are amorphous.
C)often crystallize in closest-packed structures.
D)often crystallize in very complex unit cells.
E)are like liquids with the nuclei flowing through a sea of electrons.

Question 21

Silver crystallizes with a face-centered cubic unit cell. The edge length is 407.7 pm. What is the volume of this unit cell?

A)7.68  10⁷ pm³
B)6.78  10⁷ pm³
C)8.67  10⁷ pm³
D)9.87  10⁷ pm³
E)3.88  10⁷ pm³

Question 22

Which of the following unit cells has the lowest packing efficiency?

A)simple cubic
B)face-centered cubic
C)body-centered cubic
D)both face-centered and body-centered cubic
E)Simple, face-centered, and body-centered cubic all have the same packing efficiency.

Question 23

Copper crystallizes in a face-centered cubic pattern. How many copper atoms are in each unit cell?

A)2
B)4
C)8
D)12
E)14

Question 24

Which statement does not describe a simple cubic unit cell?

A)It results from square packing of atoms in layers.
B)The atoms lie at the corners of a cube.
C)Each atom has 6 nearest neighbors.
D)The stacking pattern can be represented by aaaa.
E)Each unit cell contains 8 atoms.

Question 25

Iron crystallizes in a body-centered cubic pattern. How many iron atoms are in each unit cell?

A)1
B)2
C)4
D)8
E)9

Question 26

Compare the packing efficiency of face-centered cubic copper and simple cubic polonium.

A)The efficiency of packing in the copper unit cell is higher.
B)The efficiency of packing in the polonium unit cell is higher.
C)The efficiencies of packing in the two lattices are the same.
D)Packing efficiencies cannot be defined for one or both of these.
E)There is no way to compare without further information.

Question 27

An atom in a particular unit cell has 12 nearest neighbor atoms around it. Which unit cell(s) are possible?

A)simple cubic
B)body-centered cubic
C)face-centered cubic
D)hexagonal
E)face-centered cubic or hexagonal

Question 28

Which of the following unit cells has the highest packing efficiency?

A)simple cubic
B)face-centered cubic
C)body-centered cubic
D)both face-centered and body-centered cubic
E)Simple, face-centered, and body-centered cubic all have the same packing efficiency.

Question 29

Which unit cell contains the least atoms?

A)fcc
B)bcc
C)sc
D)both fcc and bcc
E)None of the above, as fcc, bcc, and sc contain the same number of atoms.

Question 30

Polonium crystallizes in a simple cubic pattern. How many polonium atoms are in each unit cell?

A)1
B)2
C)3
D)4
E)5

Question 31

If a body-centered cubic unit cell has a volume of 1.447  10⁸ pm³, what must be the dimension of the cube's edge?

A)1.131  10⁸ pm
B)110 pm
C)1.20  10⁴ pm
D)525 pm
E)367 pm

Question 32

An atom in a particular unit cell has 6 nearest neighbor atoms around it. Which unit cell(s) are possible?

A)simple cubic
B)body-centered cubic
C)face-centered cubic
D)hexagonal
E)face-centered cubic or hexagonal

Question 33

Compare the packing efficiency of face-centered cubic gold and face-centered cubic copper.

A)The efficiency of packing in the gold unit cell is higher.
B)The efficiency of packing in the copper unit cell is higher.
C)The efficiencies of packing in the unit cells of these two metals are the same.
D)Packing efficiencies are not defined for metals.
E)There is no way to compare without further information.

Question 34

In the cesium chloride unit cell shown below, the cesium ions sit on the corners of a cube. What is the name of this unit cell?

A)simple cubic
B)chloride-centered cubic
C)face-centered cubic
D)cubic-centered
E)body-centered cubic

Question 35

An atom in a particular unit cell has 8 nearest neighbor atoms around it. Which unit cell(s) are possible?

A)simple cubic
B)body-centered cubic
C)face-centered cubic
D)hexagonal
E)face-centered cubic or hexagonal

Question 36

How many nearest neighbor atoms are there around each atom in a body-centered cubic unit cell?

A)4
B)6
C)8
D)10
E)12

Question 37

Compare the packing efficiency of face-centered cubic gold and face-centered cubic sodium chloride considering all the atoms.

A)The efficiency of packing in the gold unit cell is higher.
B)The efficiency of packing in the sodium chloride unit cell is higher.
C)The efficiencies of packing in the two lattices are the same.
D)Packing efficiencies cannot be defined for one or both of these.
E)There is no way to compare without further information.

Question 38

How many nearest neighbor atoms are there around each atom in a face-centered cubic unit cell?

A)4
B)6
C)8
D)10
E)12

Question 39

How many nearest neighbor atoms are there around each atom in a simple cubic unit cell?

A)4
B)6
C)8
D)10
E)12

Question 40

Which unit cell contains the most atoms?

A)fcc
B)bcc
C)cubic
D)both fcc and bcc
E)None of the above, as fcc, bcc, and cubic contain the same number of atoms.

Question 41

Nickel (Ni) crystallizes as a face-centered unit cell with an edge length of 382 pm. What is the atomic radius of nickel?

A)135 pm
B)165 pm
C)191 pm
D)252 pm
E)1,080 pm

Question 42

The higher the carbon content in steel, ________

A)the stronger and more malleable it is.
B)the stronger and more brittle it is.
C)the weaker and more malleable it is.
D)the weaker and more brittle it is.
E)Any of these, depending on the formula of the interstitial compound.

Question 43

Which statement regarding the formation of an alloy is correct?

A)Carbon forms an interstitial alloy with iron because their atomic radii are about the same.
B)Carbon forms a substitutional alloy with iron because their atomic radii are about the same.
C)Carbon forms an interstitial alloy with iron because carbon has a much smaller atomic radius.
D)Carbon forms a substitutional alloy with iron because carbon has a much smaller atomic radius.
E)Carbon forms an interstitial alloy with iron because carbon has a much larger atomic radius.

Question 44

If a face-centered cubic unit cell has a volume of 1.447  10⁸ pm³ and the ions at the corners touch the ion on the face, what must be the ion's radius?

A)186 pm
B)388 pm
C)4,243 pm
D)125 pm
E)1,050 pm

Question 45

A tetrahedral hole in a crystal lattice is defined as ________

A)one-half of an octahedral hole.
B)the space between any number of atoms having tetrahedral edges.
C)the space between a cage of sp³ hybridized atoms, such as in diamond.
D)the space between a cluster of four adjacent atoms arranged in a tetrahedron.
E)a large hole having four flat sides arranged in a tetrahedral shape.

Question 46

Which of the following refers to an alloy in which the composition of the elements is variable and one element must have a much smaller radius than the other?

A)intermetallic
B)interstitial
C)stoichiometric
D)substitutional
E)inhomogeneous

Question 47

Iron (Fe) has a density of 7.874 g/cm³ and crystallizes in a body-centered cubic structure. What is the atomic radius of iron?

A)99 pm
B)114 pm
C)124 pm
D)143 pm
E)255 pm

Question 48

The alpha form of polonium (Po) has a density of 9.196 g/cm³ and crystallizes in a simple cubic structure. What is the atomic radius of polonium?

A)119 pm
B)168 pm
C)266 pm
D)335 pm
E)419 pm

Question 49

In addition to carbon and iron, stainless steel contains ________

A)Teflon and polyethylene.
B)gold and silver.
C)copper and nickel.
D)chromium and nickel.
E)platinum.

Question 50

Which of the following refers to an alloy in which the composition is variable and the elements have comparable radii?

A)intermetallic
B)interstitial
C)stoichiometric
D)substitutional
E)homogeneous

Question 51

Aluminum (Al) has a density of 2.70 g/cm³ and crystallizes in a face-centered cubic structure. What is the unit cell edge length?

A)2.47  10^-3 pm
B)40.0 pm
C)405 pm
D)321 pm
E)255 pm

Question 52

Platinum (Pt) has a face-centered cubic structure with an edge length of 135 pm. What is the calculated value of the density of platinum based on this information?

A)1.03 g/cm³
B)5.81 g/cm³
C)11.63 g/cm³
D)173 g/cm³
E)527 g/cm³

Question 53

Which of the following refers to an alloy in which the composition of the elements is constant?

A)intermetallic
B)interstitial
C)stoichiometric
D)substitutional
E)homogeneous

Question 54

The alpha form of polonium (Po) crystallizes as a simple cubic unit cell with an edge length of 335 pm. What is the atomic radius of polonium?

A)84 pm
B)168 pm
C)335 pm
D)175 pm
E)808 pm

Question 55

Iron (Fe) crystallizes as a body-centered unit cell and has an atomic radius of 126 pm. What is the edge length for the unit cell of iron?

A)55 pm
B)63 pm
C)252 pm
D)291 pm
E)356 pm

Question 56

Bronze that is composed of 10% tin and 90% copper is ________

A)a substitutional alloy.
B)an interstitial alloy.
C)a doped semiconductor.
D)a colloidal alloy.
E)an intermetallic compound.

Question 57

An octahedral hole in a crystal lattice is defined as ________

A)twice the size of a tetrahedral hole.
B)the space between any number of atoms having octahedral edges.
C)the space between a cluster of six adjacent atoms arranged in a octahedron.
D)the space between layers of sp² hybridized atoms, such as in graphite.
E)a large hole having six sides arranged in an octahedral shape.

Question 58

Gold has a face-centered cubic structure with a unit cell edge length of 407.8 pm. What is the contribution to the density from each individual gold atom?

A)21.44 g/cm³
B)26.20 g/cm³
C)13.1 g/cm³
D)6.55 g/cm³
E)19.28 g/cm³

Question 59

Which of the following can be varied to change the physical properties of an alloy?
I.the elements used
II.the proportions used
III.the type of hole each element occupies

A)I only
B)II only
C)III only
D)I and II only
E)I, II, and III

Question 60

In a two-component alloy the more abundant metal can be thought of as the solvent while the less abundant metal can be thought of as the solute. Which of the following would not change the position of atoms in the solvent's unit cell?
I.a solute with the same atomic radius as the solvent
II.a solute that was sufficiently small to fit into holes in the solvent's unit cell
III.a solvent that was sufficiently small to fit into holes in the solute's unit cell

A)I only
B)II only
C)III only
D)I or II
E)I, II, or III

Question 61

A face-centered cubic unit cell contains ________ octahedral holes.

A)1
B)4
C)8
D)12
E)13

Question 62

In fluorite, ________

A)cations are smaller than the anions, and there are two cations for every anion.
B)anions are smaller than the cations, and there are two anions for every cation.
C)cations are smaller than the anions, and there are two anions for every cation.
D)anions are smaller than the cations, and there are two cations for every anion.
E)anions and cations are the same size.

Question 63

In antifluorite structures, ________

A)cations are smaller than the anions, and there are two cations for every anion.
B)anions are smaller than the cations, and there are two anions for every cation.
C)cations are smaller than the anions, and there are two anions for every cation.
D)anions are smaller than the cations, and there are two cations for every anion.
E)anions and cations are the same size.

Question 64

The face-centered cubic unit cell has ________ tetrahedral holes.

A)0
B)1
C)4
D)8
E)12

Question 65

What is the likely unit cell for ionic compounds of 1:1 stoichiometry in which the difference in the radii is only about 25% or less?

A)rock salt
B)sphalerite
C)fluorite
D)cubic
E)antifluorite

Question 66

In comparing the density of bronze composed of 20% tin to the density of pure copper, ________

A)the density of the bronze is higher.
B)the density of the bronze is lower.
C)the density of the bronze is the same.
D)the density of the bronze depends on whether the tin or the copper occupies holes.
E)It cannot be determined, because only the 1:1 intermetallic compound of tin and copper has ever been observed.

Question 67

Stainless steel is less susceptible to rusting than iron because ________

A)it is coated with plastic.
B)the metals other than iron in the alloy form protective oxides.
C)the carbon within the alloy polymerizes to form a protective film.
D)the silicon within the alloy oxidizes to form a protective silicate layer.
E)the intermetallic compound formed is less reactive.

Question 68

What type of hole is depicted below? The gray circle represents the top layer.

A)tetrahedral hole
B)octahedral hole
C)cubic hole
D)both an octahedral and tetrahedral hole
E)both an octahedral and cubic hole

Question 69

What type of hole is depicted below? The gray circles represent the top layer.

A)tetrahedral hole
B)octahedral hole
C)cubic hole
D)both an octahedral and tetrahedral hole
E)both an octahedral and cubic hole

Question 70

In interstitial alloys, a maximum (  1) atomic radius ratio would indicate an atom would likely fit in what type of hole(s)?

A)tetrahedral hole
B)octahedral hole
C)cubic hole
D)both an octahedral and tetrahedral hole
E)both an octahedral and cubic hole

Question 71

In the cubic closest-packed structure of sodium chloride, which ions are touching or nearly touching?
I.sodium ions and sodium ions
II.chloride ions and chloride ions
III.sodium ions and chloride ions

A)I only
B)II only
C)III only
D)II and III only
E)I and III only

Question 72

If half of the tetrahedral holes in a face-centered cubic unit cell are filled, what must be the stoichiometry of the ionic compound, written as nonhole sites:hole sites in lowest terms?

A)2:1
B)1:1
C)1:2
D)4:1
E)2:3

Question 73

The center of a cubic hole is found ________

A)at the center of a simple cubic lattice.
B)on the edges of a simple cubic lattice.
C)on the faces of a body-centered cubic lattice.
D)at the center of a face-centered cubic lattice.
E)at eight sites within a face-centered cubic lattice.

Question 74

In interstitial alloys, a small (  0.3) atomic radius ratio would indicate an atom would fit in what type of hole(s)?

A)tetrahedral hole
B)octahedral hole
C)cubic hole
D)both an octahedral and tetrahedral hole
E)both an octahedral and cubic hole

Question 75

Aluminum alloys are more desirable than steel in some applications because of their relatively ________

A)low density.
B)low cost.
C)high luster.
D)high warmth to touch.
E)high conductivity.

Question 76

Aluminum is resistant to corrosion because of ________

A)its positive oxidation potential.
B)its low density.
C)the formation of a protective surface film of aluminum oxide.
D)the formation of a protective surface film of aluminum nitride.
E)its lack of reactivity toward oxygen.

Question 77

If a salt has a face-centered cubic (fcc) unit cell and a 1:2 cation:anion stoichiometry with cations occupying the fcc positions, then the anions fill all the ________ holes.

A)Cubic
B)octahedral
C)tetrahedral
D)octahedral and tetrahedral
E)cubic, octahedral, and tetrahedral

Question 78

A face-centered cubic unit cell has a(n) ________ in its center.

A)tetrahedral hole
B)octahedral hole
C)Atom
D)square planar hole
E)cubic hole

Question 79

Why does a pure metal not crystallize in a fluorite or antifluorite unit cell?

A)They can and do.
B)These unit cells require two types of atoms or ions with differing radii.
C)Pure metals do not crystallize; they are amorphous.
D)The atoms in pure metals move about in a sea of electrons.
E)The radius of the metal is too large.

Question 80

A rock salt structure has smaller ions in ________

A)cubic holes.
B)tetrahedral holes.
C)hexagonal holes.
D)octahedral holes.
E)the usual atomic positions in the unit cell, i.e., not in holes.