Deck 12: Solids and Modern Materials

Question 1

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

Answer 1

thermal conductivity

Question 2

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

Answer 2

increase in hardness and strength, decrease in ductility

Question 3

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.

Answer 3

the atomic ratios of the constituent elements in the former are not fixed and may vary over a wide range.

Question 4

Intermetallic compounds are examples of

A)homogeneous alloys.
B)heterogeneous alloys.
C)interstitial alloys.
D)solution alloys.
E)ionic compounds.

Question 5

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

Question 6

Which element is typically not added to steel to modify its properties?

A)carbon
B)vanadium
C)chromium
D)nitrogen
E)nickel

Question 7

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

Question 8

The scattering of light waves upon passing through a narrow slit is called __________.

A)diffusion
B)grating
C)diffraction
D)adhesion
E)incidence

Question 9

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.

Question 10

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

Question 11

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.

Question 12

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

Question 13

Which of the following is not a type of solid?

A)ionic
B)molecular
C)supercritical
D)metallic
E)covalent-network

Question 14

Which of the following is not an alloy?

A)brass
B)steel
C)sterling silver
D)dental amalgam
E)ceramic

Question 15

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

Question 16

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

Question 17

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.

Question 18

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

Question 19

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.

Question 20

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

Question 21

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

Question 22

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

Question 23

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

Question 24

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.

Question 25

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

Question 26

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

Question 27

The empirical formula of an addition polymer __________.

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

Question 28

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

Question 29

Metallic solids do not exhibit __________.

A)excellent thermal conductivity
B)excellent electrical conductivity
C)variable hardness
D)extreme brittleness
E)variable melting point

Question 30

Of the following, only __________ is not a polymer.

A)cellulose
B)nylon
C)starch
D)protein
E)stainless steel

Question 31

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

Question 32

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

Question 33

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

Question 34

Of the following, only __________ is an addition polymer.

A)polyethylene terephthalate
B)polystyrene
C)polyurethane
D)polycarbonate
E)Nylon 6,6

Question 35

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

Question 36

Which of the following is not a natural polymer?

A)silk
B)starch
C)protein
D)cellulose
E)nylon

Question 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.

Question 38

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

Question 39

The monomer that is polymerized to make natural rubber is __________.

A)melamine
B)formaldehyde
C)ethylene
D)isoprene
E)adipic acid

Question 40

Inorganic compounds that are semiconductors have an average of __________ valence electrons.

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

Question 41

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

Question 42

A material that contains more than one element and has the characteristic properties of metals is called a (an)__________.

Question 43

When lattice points occur only at the corners of a unit cell, the cell is called __________.

Question 44

12 karat gold contains __________% gold.

A)12
B)25
C)5.0 x 10¹
D)75
E)1.0 x 10²

Question 45

18 karat gold contains __________% gold.

A)18
B)25
C)89
D)75
E)1.0 x 10²

Question 46

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.

Question 47

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

Question 48

24 karat gold contains __________% gold.

A)24
B)25
C)5.0 x 10¹
D)75
E)1.00 x 10²

Question 49

__________ 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

Question 50

The transition metals in group __________ have the highest melting points.

A)4B
B)3B
C)6B
D)8B
E)2B

Question 51

6.0 karat gold contains __________% gold.

A)6.0
B)25
C)5.0 x 10¹
D)75
E)1.0 x 10²

Question 52

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

Question 53

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

Question 54

When lattice points occur at the center of each face, as well as each corner of a unit cell, the cell is called __________.

Question 55

Blue LEDs are usually made of __________.

A)GaAs
B)GaP
C)GaO
D)GaS
E)GaN

Question 56

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

Question 57

A category __________ plastic container will generally be the most easily recycled.

A)1
B)2
C)3
D)4
E)22

Question 58

How many atoms are contained in a face-centered cubic unit cell?

Question 59

When lattice points occur at the corners and at the center of a unit cell, the cell is called __________.

Question 60

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

Question 61

Semiconductors are less conductive than metals because of __________ gap.

Question 62

Many metals are ductile, which means that they can be hammered into thin sheets.

Question 63

__________ are solid-state materials that can be made either semiconducting or metallic without any doping.

Question 64

What two metals are alloyed to produce sterling silver?

Question 65

The process of adding controlled amounts of impurity atoms to a material is known as __________.

Question 66

Polymers formed from two different monomers are called __________.

Question 67

Chromium crystallizes in a body-centered cubic unit cell. There are __________ chromium atoms per unit cell.

Question 68

The dopant atoms in an n-type semiconductor have __________ electrons than the host material.

Question 69

Nylon is formed by the reaction of a __________ with a __________.

Question 70

Silicon technology is based on the fact that silicon oxide is a chemically stable conductor.

Question 71

Polyethylene is formed by a condensation reaction.

Question 72

In addition to differences in their average molecular mass, HDPE and LDPE differ in their degree of __________ and their __________ of the chains.

Question 73

Write the chemical formulas for both polyethylene and the monomer from which it is formed.

Question 74

Vulcanization involves heating rubber with sulfur dioxide to produce a thermosetting polymer.

Question 75

A plasticizer makes a polymer more pliable by reducing the interactions between polymer chains.

Question 76

Semiconductor particles with diameters of 1-10 nm are called __________.

Question 77

__________ are materials characterized by an energy gap between a filled valence band and an empty conduction band.

Question 78

The type of solid that is characterized by low melting point, softness, and low electrical conduction is a covalent-network solid.