Question 1

An approximately spherical allotrope of carbon containing 60 or 70 atoms is __________

Accepted Answer

The term "fullerene" specifically refers to an approximately spherical allotrope of carbon containing 60 or 70 atoms arranged in a pattern resembling the 32 faces of a truncated icosahedron. Options A and B are not actual names of known fullerenes, and options D and E are not valid scientific names for any carbon allotrope.

Question 2

In the solid-state structure of sodium chloride, the closest distance between the centers of ions is observed __________

Accepted Answer

In the solid-state structure of sodium chloride (NaCl), each sodium ion is surrounded by six chloride ions and each chloride ion is surrounded by six sodium ions in an octahedral geometry. This arrangement is consistent throughout the crystal, meaning the closest distance between the centers of ions is observed between all adjacent sodium and chloride ions, reflecting the highly symmetrical and uniform nature of the NaCl crystal structure.

Question 3

How many tennis balls will fit within the interstitial holes between a truckload of basketballs perfectly placed in a closest-packed arrangement? Assume that the tennis balls have a radius that is 20% that of a basketball.

Accepted Answer

The answer of How many tennis balls will fit within...

Question 4

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

Accepted Answer

A face-centered cubic (FCC) unit cell contains 4 octahedral holes. There is one octahedral hole at the center of the cell and 12 edges, each contributing 1/4 of an octahedral hole, totaling 3 from the edges.

Question 5

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.

Accepted Answer

(I) It is electrostatic: This is true since the attractive force between the sodium and chloride ions is due to the opposite charges of the ions, which are held together by electrostatic forces.
(II) It is termed ionic bonding: This is also true since sodium chloride is an ionic compound and the attractive force between the sodium and chloride ions is due to ionic bonding.
(III) It depends on the distance between the sodium and chloride: This is true since the strength of the attractive force between the ions depends on their distance from each other, with the force increasing as the distance decreases.
(IV) It only operates between adjacent sodium and chloride: This is not true since the attractive force operates between all sodium and chloride ions in the crystal lattice, not just adjacent ions.

Question 6

In the cubic closest-packed structure of sodium chloride, what ions are touching or nearly touching?
(I)Sodium ions and sodium ions
(II)Chloride ions and chloride ions
(III)Sodium ions and chloride ions

Accepted Answer

In a cubic closest-packed structure, each ion is surrounded by 6 ions of opposite charge forming an octahedron. Therefore, in sodium chloride, sodium ions and chloride ions are touching or nearly touching each other. There is no such interaction between ions of the same charge. Therefore, option I is incorrect, and option II is not clear regarding which ions are being referred to. Option III is correct, but option D is the best choice as it includes both options II and III.

Question 7

Which of the following figures best represents a common structure within crystalline sulfur? (A sulfur atom lies at each vertex.)

Accepted Answer

The answer of Which of the following figures best represents...

Question 8

Boron nitride, BN, is solid under standard conditions. Which of the following structures would you expect it to most resemble?

Accepted Answer

Boron nitride has a crystal structure similar to graphite, consisting of hexagonal rings of alternating boron and nitrogen atoms arranged in layers.

Question 9

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

Accepted Answer

The answer of Compare the packing efficiency of face-centered cubic...

Question 10

As an analog of graphite, a material composed of boron and nitrogen (B-N) has been prepared. Why do these elements make a good substitute for the element in graphite?
(I)They are all elements with electrons in the 2p subshell.
(II)The sum of the valence electrons of one boron atom and one nitrogen atom is the same as the number of valence electrons on two carbon atoms.
(III)Boron and nitrogen have suitable 2p orbital overlap.

Accepted Answer

(I) Boron and nitrogen have electrons in the 2p subshell, just like carbon in graphite, but this alone is not sufficient to make a good substitute for carbon in graphite.
(II) The sum of the valence electrons of one boron atom and one nitrogen atom is 7, just like the valence electrons of two carbon atoms. This is important because the properties of graphite come from its valence electrons, and a B-N material with the same number of valence electrons as graphite can potentially have similar properties.
(III) Boron and nitrogen have suitable 2p orbital overlap, which is necessary for the formation of covalent bonds between these two elements to make a B-N material.

Question 11

A rock salt structure has smaller ions in __________

Accepted Answer

In a rock salt structure, the larger ions form a face-centered cubic lattice while the smaller ions occupy octahedral holes between the larger ions. Hence, the correct answer is D, i.e., smaller ions are in octahedral holes.

Question 12

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

The answer of Which of the following contribute to the...

Question 13

The sheet structure of carbon is __________

Accepted Answer

The sheet structure of carbon refers to the arrangement of carbon atoms in a two-dimensional, planar pattern. This is seen in the structure of graphite, where carbon atoms are arranged in hexagonal rings that stack on top of each other to form sheets. Diamond is a three-dimensional crystal structure, while fullerene refers to a spherical shape composed of carbon atoms. Industrial diamond and rolled carbon steel both refer to materials made from carbon, but they do not possess a sheet structure.

Question 14

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

Accepted Answer

The answer of A face-centered cubic unit cell has a(n)...

Question 15

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

Accepted Answer

The face-centered cubic (FCC) unit cell has 8 tetrahedral holes. Each FCC unit cell consists of 8 corner atoms and 6 face-centered atoms, creating a total of 8 tetrahedral holes within the structure.

Question 16

Would you expect the linear allotrope of carbon to conduct electricity? (Fragments of it were first prepared and characterized in 1998.)

Accepted Answer

The delocalized pi electron network in the linear carbon allotrope would allow for electron movement and therefore conductivity.

Question 17

A tetrahedral hole in a crystal lattice is defined as __________

Accepted Answer

A tetrahedral hole is defined as the space between a cluster of four adjacent atoms arranged in a tetrahedron.

Question 18

Which of these is the best conductor of electricity?

Accepted Answer

Graphite is the best conductor of electricity among the given options as it has a delocalized electron system that allows for the easy flow of electrons. Diamond, glass, and fullerene are all insulators, while water is a poor conductor of electricity.

Question 19

Researchers at the University of Texas at Austin prepared a linear allotrope of carbon in 1998. What is the hybridization of its atomic orbitals?

Accepted Answer

The linear allotrope of carbon is known as carbyne or linear carbon chain. It consists of carbon atoms arranged in a linear fashion with alternating single and triple bonds. The triple bonds require sp hybridization of the carbon atoms involved, while the single bonds require sp2 hybridization. Therefore, the hybridization of carbyne is sp.

Question 20

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

Accepted Answer

Fluorite and antifluorite unit cells require two types of atoms or ions with differing radii, whereas pure metals consist of only one type of atom and do not have such variations in size.

Quiz 12: The Chemistry of Solids