Q: Which of the following is the correct formula for the number of atoms per unit cell in a face-centered cubic (FCC) lattice?

$$8 \times \frac{1}{8} + 6 \times \frac{1}{2} = 4$$

Q: A metal crystallizes in a body-centered cubic (BCC) structure. How many atoms are present in one unit cell?

$$8 \times \frac{1}{8} + 1 = 2$$

Question 1

Which of the following statements best distinguishes a crystalline solid from an amorphous solid?

Accepted Answer

Crystalline solids have a regular repeating pattern of atoms, while amorphous solids lack long-range order.

Question 2

X-ray diffraction is a powerful tool in solid-state chemistry. What information does X-ray diffraction provide about a crystalline solid?

Accepted Answer

It reveals the arrangement of atoms within the unit cell and the identity of the unit cell.

Question 3

Which of the following is the correct formula for the number of atoms per unit cell in a face-centered cubic (FCC) lattice?

Accepted Answer

$$8 	imes \frac{1}{8} + 6 	imes \frac{1}{2} = 4$$

Question 4

A metal crystallizes in a body-centered cubic (BCC) structure. How many atoms are present in one unit cell?

Accepted Answer

$$8 	imes \frac{1}{8} + 1 = 2$$

Question 5

Which of the following best explains why CsCl and NaCl, both with a 1:1 cation to anion ratio, have different lattice structures?

Accepted Answer

The difference in the size of the cations (Cs+ is much larger than Na+), leading to different packing arrangements.

Question 6

Which type of cubic unit cell has atoms only at the corners of the cube?

Accepted Answer

Primitive cubic

Question 7

In a face-centered cubic (FCC) unit cell, what fraction of each face atom belongs to a single unit cell?

Accepted Answer

$$\frac{1}{2}$$

Question 8

Which of the following best describes the bonding in metallic solids?

Accepted Answer

A 'sea' of delocalized electrons surrounding positive metal ions.

Question 9

Which of the following is a real-world application of the Born-Haber cycle?

Accepted Answer

Calculating the lattice energy of an ionic compound such as NaCl.

Question 10

A sample of CaF$$_2$$ crystallizes in a cubic unit cell. If there are 4 formula units per unit cell, what is the cube formula?

Accepted Answer

Ca$$_4F$_8$$

Question 11

Which of the following statements about ionic solids is correct?

Accepted Answer

They are held together by electrostatic attractions between cations and anions.

Question 12

Which of the following best describes the coordination number in a crystal lattice?

Accepted Answer

The number of nearest neighbor ions of opposite charge surrounding a central ion.

Question 13

Which of the following is a property of covalent-network solids?

Accepted Answer

They have high melting points due to extensive covalent bonding.

Question 14

Which of the following is the correct sequence of steps in the Born-Haber cycle for the formation of NaCl(s) from its elements?

Accepted Answer

Sublimation of Na(s), dissociation of Cl$$_2(g$$), ionization of Na(g), electron affinity of Cl(g), lattice energy.

Question 15

Which of the following best explains why ionic solids are typically electrical insulators in the solid state?

Accepted Answer

The ions are fixed in place and cannot move to conduct electricity.

Question 16

A cubic unit cell contains 8 corner atoms and 6 face atoms. What is the total number of atoms per unit cell?

Accepted Answer

$$8 	imes \frac{1}{8} + 6 	imes \frac{1}{2} = 4$$

Question 17

Which of the following is a real-life example of a covalent-network solid?

Accepted Answer

Diamond

Question 18

Which of the following best describes the difference between substitutional and interstitial alloys?

Accepted Answer

Substitutional alloys have atoms of similar size replacing each other; interstitial alloys have smaller atoms fitting into spaces between larger atoms.

Question 19

Which of the following is the correct formula for the lattice energy ($$\Delta U_{lattice}) in $$the Born-Haber cycle?

Accepted Answer

$$\Delta U_{lattice} = \Delta H_{f} - (	ext{Sublimation} + 	ext{Ionization} + 	ext{Dissociation} + 	ext{Electron Affinity})$$

Solids and Modern Materials: Structure, Types, and Lattice Energy

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