Question 1

Which of the following best describes a unit cell in a crystalline solid?

Accepted Answer

A repeating three-dimensional arrangement of atoms, ions, or molecules that defines the entire structure of the solid.

Question 2

Which type of cubic unit cell has the highest packing efficiency?

Accepted Answer

Face-centered cubic (FCC)

Question 3

What is the coordination number for a body-centered cubic (BCC) unit cell?

Accepted Answer

$8$

Question 4

Given a face-centered cubic (FCC) unit cell with an atomic radius $r$, what is the length of the edge of the unit cell ($a$)?

Accepted Answer

$a = 2\sqrt{2}r$

Question 5

Which of the following statements about packing efficiency is correct?

Accepted Answer

Face-centered cubic structures are more efficiently packed than body-centered cubic structures.

Question 6

A metal crystallizes in a simple cubic unit cell. If the atomic radius is $r$, what is the volume of the unit cell?

Accepted Answer

$V = (2r)^3$

Question 7

Which type of crystalline solid is most likely to have the highest melting point?

Accepted Answer

Ionic solid

Question 8

Which of the following is a property typical of molecular solids?

Accepted Answer

Low melting points and poor electrical conductivity

Question 9

Which statement best describes the difference between ionic and molecular solids?

Accepted Answer

Ionic solids are held together by electrostatic forces, while molecular solids are held together by intermolecular forces.

Question 10

A crystalline solid has a coordination number of $6$. Which type of unit cell is most likely present?

Accepted Answer

Simple cubic

Question 11

Which of the following best explains why ionic solids generally have higher melting points than molecular solids?

Accepted Answer

Ionic solids are held together by strong electrostatic attractions between ions.

Question 12

If the edge length of a body-centered cubic unit cell is $a$, what is the relationship between $a$ and the atomic radius $r$?

Accepted Answer

$a = \frac{4r}{\sqrt{3}}$

Question 13

Which of the following is NOT a fundamental type of crystalline solid?

Accepted Answer

Amorphous solid

Question 14

A certain crystalline solid is a poor conductor of electricity, has a low melting point, and consists of discrete molecules. What type of solid is this?

Accepted Answer

Molecular solid

Question 15

Which of the following best describes the packing efficiency of a simple cubic unit cell?

Accepted Answer

It is the least efficiently packed among the cubic unit cells.

Question 16

Which property is most likely to be observed in an atomic solid such as diamond?

Accepted Answer

High melting point and hardness

Question 17

Which of the following is true about the melting points of crystalline solids?

Accepted Answer

Ionic solids generally have higher melting points than molecular solids.

Question 18

Which of the following is a real-world example of a molecular solid?

Accepted Answer

Ice ($\mathrm{H_2O}$)

Question 19

Which of the following statements about unit cells is correct?

Accepted Answer

The unit cell is the smallest repeating unit that shows the full symmetry of the crystal structure.

Question 20

A crystalline solid is composed of ions arranged in a regular pattern. Which type of solid is this?

Accepted Answer

Ionic solid

Chem chapter 12 study guide

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