Q: A sample of NaCl forms a cubic unit cell. If the edge length of the unit cell is $564 \ \mathrm{pm}$, what is the volume of the unit cell in $\mathrm{cm}^3$?

$1.79 \times 10^{-22} \ \mathrm{cm}^3$

Question 1

Which of the following best describes the main difference between molecular, ionic, and atomic (network) crystalline solids?

Accepted Answer

Molecular solids are composed of molecules held together by intermolecular forces, ionic solids are composed of ions held together by electrostatic forces, and atomic solids are composed of atoms held together by covalent bonds.

Question 2

A sample of NaCl forms a cubic unit cell. If the edge length of the unit cell is $564 \ \mathrm{pm}$, what is the volume of the unit cell in $\mathrm{cm}^3$?

Accepted Answer

$1.79 	imes 10^{-22} \ \mathrm{cm}^3$

Question 3

Which of the following statements about X-ray diffraction is correct?

Accepted Answer

X-ray diffraction allows for the determination of the arrangement of atoms within a crystal by analyzing the pattern of scattered X-rays.

Question 4

Which equation is used to relate the angle of diffraction ($	heta$), the wavelength ($\lambda$), and the distance between planes in a crystal ($d$) in X-ray diffraction?

Accepted Answer

$n \lambda = 2d \sin 	heta$

Question 5

Which of the following best explains why diamond has a much higher melting point than sodium chloride?

Accepted Answer

Diamond is an atomic (network) solid with strong covalent bonds throughout the structure, while sodium chloride is held together by ionic bonds.

Question 6

A metal crystallizes in a face-centered cubic (FCC) lattice. How many atoms are present in one unit cell?

Accepted Answer

4

Question 7

Which of the following is a correct statement about the band theory of solids?

Accepted Answer

In metals, the valence band and conduction band overlap, allowing electrons to move freely.

Question 8

Which property is most likely to increase as the atomic radius of a metal increases, assuming the same crystal structure?

Accepted Answer

Unit cell volume

Question 9

Which of the following best describes the structure of a silicate mineral?

Accepted Answer

Silicate minerals are composed of $\mathrm{SiO}_4$ tetrahedra linked in various ways, including chains, sheets, and three-dimensional frameworks.

Question 10

Which of the following polymers is most likely to be flexible and have a low melting point?

Accepted Answer

A polymer with weak intermolecular forces and little or no cross-linking.

Question 11

A certain ionic compound has a formula unit of $\mathrm{AB}_2$ and crystallizes in a cubic unit cell. If the ions A occupy the corners and the ions B occupy the centers of each face, what is the coordination number of ion A?

Accepted Answer

8

Question 12

Which of the following statements about the melting points of ionic and molecular solids is correct?

Accepted Answer

Ionic solids generally have higher melting points due to strong electrostatic attractions between ions.

Question 13

Which of the following best explains why graphite conducts electricity while diamond does not?

Accepted Answer

Graphite has delocalized electrons within its layers, while diamond has localized electrons in covalent bonds.

Question 14

Which of the following is a correct application of the concept of packing efficiency in crystal structures?

Accepted Answer

Packing efficiency is the ratio of the volume occupied by the atoms to the total volume of the unit cell.

Question 15

Which of the following best describes an amorphous solid?

Accepted Answer

An amorphous solid lacks long-range order in the arrangement of its particles.

Question 16

Which of the following is a correct statement about the relationship between unit cell volume and density?

Accepted Answer

Density is calculated as $	ext{Density} = \frac{	ext{mass of unit cell}}{	ext{volume of unit cell}}$.

Study Guide: Solids, Crystalline Structures, and Related Properties (General Chemistry)

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