Question 1

Different structural forms of the elements are called ________

Accepted Answer

A)  polymers. 
B)  allotropes. 
C)  isotopes. 
D)  isoforms. 
E)  polymorphs. 
A)  polymers. 
B)  allotropes. 
C)  isotopes. 
D)  isoforms. 
E)  polymorphs. B

Question 2

A tetrahedral hole in a crystal lattice is defined as ________

Accepted Answer

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. 
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. D

Question 3

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?

Accepted Answer

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 
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 B

Question 4

How many carbons are bonded to each carbon in graphite?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  some have 2 and some have 3 
A)  1 
B)  2 
C)  3 
D)  4 
E)  some have 2 and some have 3

Question 5

Superconductivity involves the formation of ________

Accepted Answer

A)  electron tunnels. 
B)  phase-matched electron waves. 
C)  Cooper pairs. 
D)  electron yokes. 
E)  Meissner couples. 
A)  electron tunnels. 
B)  phase-matched electron waves. 
C)  Cooper pairs. 
D)  electron yokes. 
E)  Meissner couples.

Question 6

Aluminum (Al) crystallizes as a face-centered unit cell with an edge length of 404 pm. What is the atomic radius of aluminum in picometers?

Accepted Answer

The answer of Aluminum (Al) crystallizes as a face-centered unit...

Question 7

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.

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

Compounds like silicon dioxide that can have the same empirical formula but different crystal structures and properties are termed ________

Accepted Answer

A)  allotropes. 
B)  allomorphs. 
C)  isomorphs. 
D)  isotopes. 
E)  polymorphs. 
A)  allotropes. 
B)  allomorphs. 
C)  isomorphs. 
D)  isotopes. 
E)  polymorphs.

Question 11

What similarities are there in the motion of electrons about an atom and electrons being conducted in a superconducting ceramic?

Accepted Answer

A)  The electrons move in circular orbits. 
B)  Two electrons move in opposite directions but with the same path. 
C)  The electrons move without loss of kinetic energy. 
D)  The electrons move in all directions at once, as light does. 
E)  The electrons move in Cooper pairs. 
A)  The electrons move in circular orbits. 
B)  Two electrons move in opposite directions but with the same path. 
C)  The electrons move without loss of kinetic energy. 
D)  The electrons move in all directions at once, as light does. 
E)  The electrons move in Cooper pairs.

Question 12

According to band theory, when the lower energy ________ band is separated from the higher energy ________ band by a small band gap, the material will act as a ________ of electricity.

Accepted Answer

valence; c

Question 13

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

Accepted Answer

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

Question 14

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?

Accepted Answer

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

Question 15

Potassium bromide crystallizes in the rock salt structure. It has a density of 2.75 g/cm3. What is the edge length of the unit cell? In the rock salt structure, the bromide ions form an fcc unit cell, and the potassium ions occupy the octahedral holes.

Accepted Answer

A)  220 pm 
B)  330 pm 
C)  440 pm 
D)  550 pm 
E)  660 pm 
A)  220 pm 
B)  330 pm 
C)  440 pm 
D)  550 pm 
E)  660 pm

Question 16

The center of a cubic hole is found ________

Accepted Answer

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. 
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 17

In ionic solids, one ion often occupies holes in the unit cell defined by the other ion. In a simple cubic cell, what are the types of holes that are found and the number of holes of each type?

Accepted Answer

type: cubi

Question 18

Which is not true about a crystallographic unit cell?

Accepted Answer

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. 
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 19

Which statement A-D regarding semiconductors is not correct?

Accepted Answer

A)  An undoped semiconductor does not conduct electricity because it has a filled valence band and a vacant conduction band. 
B)  Doping silicon with phosphorous produces an n-type semiconductor. 
C)  An n-type semiconductor has electrons in its conduction band. 
D)  Doping silicon with gallium removes electrons from the valence band to enhance the conductivity. 
E)  Statements A-D all are correct. 
A)  An undoped semiconductor does not conduct electricity because it has a filled valence band and a vacant conduction band. 
B)  Doping silicon with phosphorous produces an n-type semiconductor. 
C)  An n-type semiconductor has electrons in its conduction band. 
D)  Doping silicon with gallium removes electrons from the valence band to enhance the conductivity. 
E)  Statements A-D all are correct.

Question 20

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

Accepted Answer

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. 
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.

Exam 12: Solids: Structures and Applications

Different structural forms of the elements are called ________

A tetrahedral hole in a crystal lattice is defined as ________

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?

How many carbons are bonded to each carbon in graphite?

Superconductivity involves the formation of ________

Aluminum (Al) crystallizes as a face-centered unit cell with an edge length of 404 pm. What is the atomic radius of aluminum in picometers?

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.

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

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

Compounds like silicon dioxide that can have the same empirical formula but different crystal structures and properties are termed ________

What similarities are there in the motion of electrons about an atom and electrons being conducted in a superconducting ceramic?

According to band theory, when the lower energy ________ band is separated from the higher energy ________ band by a small band gap, the material will act as a ________ of electricity.

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

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?

Potassium bromide crystallizes in the rock salt structure. It has a density of 2.75 g/cm3. What is the edge length of the unit cell? In the rock salt structure, the bromide ions form an fcc unit cell, and the potassium ions occupy the octahedral holes.

The center of a cubic hole is found ________

In ionic solids, one ion often occupies holes in the unit cell defined by the other ion. In a simple cubic cell, what are the types of holes that are found and the number of holes of each type?

Which is not true about a crystallographic unit cell?

Which statement A-D regarding semiconductors is not correct?

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

Matter and Energy: The Origin of the Universe

Atoms, Ions, and Molecules: Matter Starts Here

Stoichiometry: Mass, Formulas, and Reactions

Solution Chemistry: The Hydrosphere

Thermochemistry: Energy Changes in Reactions

Properties of Gases: the Air We Breathe

A Quantum Model of Atoms: Waves and Particles

Chemical Bonds: What Makes a Gas a Greenhouse Gas

Molecular Geometry: Shape Determines Function

Intermolecular Forces: The Uniqueness of Water

Solutions: Properties and Behavior

Organic Chemistry: Fuels, Pharmaceuticals, Materials, and Life

Chemical Kinetics: Reactions in the Air We Breathe

Chemical Equilibrium: How Much Product Does a Reaction Really Make

Acid-Base and Solubility Equilibria: Reactions in Soil and Water

Metal Ions: Colorful and Essential

Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

Electrochemistry: the Quest for Clean Energy

Biochemistry: the Compounds of Life

Nuclear Chemistry: Applications to Energy and Medicine

Life and the Periodic Table

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According to band theory, when the lower energy band is separated from the higher energy band by a small band gap, the material will act as a of electricity.

Potassium bromide crystallizes in the rock salt structure. It has a density of 2.75 g/cm³. What is the edge length of the unit cell? In the rock salt structure, the bromide ions form an fcc unit cell, and the potassium ions occupy the octahedral holes.