The Foundations of Chemistry

TT

he molecules of most gases are so widely separated at ordinary temperatures and
pressures that they do not interact with one another significantly. The physical
properties of gases are reasonably well described by the simple relationships in
Chapter 12. In liquids and solids, the so-called condensed phases,the particles are close
together so they interact strongly. Although the properties of liquids and solids can be
described, they cannot be adequately explained by simple mathematical relationships. Table
13-1 and Figure 13-1 summarize some of the characteristics of gases, liquids, and solids.

Figure 13-1 Representations of the kinetic–molecular description of the three phases of
matter.

CHAPTER 13: Liquids and Solids 485

TABLE 13-1 Some Characteristics of Solids, Liquids, and Gases

Solids

1.Have definite shape (resist

deformation)

2.Are nearly incompressible

3.Usually have higher density than

liquids

4.Are not fluid

5.Diffuse only very slowly through

solids

6.Have an ordered arrangement of

particles that are very close together;

particles have vibrational motion only

Liquids

1.Have no definite shape (assume

shapes of containers)

2.Have definite volume (are only very

slightly compressible)

3.Have high density

4.Are fluid

5.Diffuse through other liquids

6.Consist of disordered clusters of

particles that are quite close together;

particles have random motion in three

dimensions

Gases

1.Have no definite shape (fill containers

completely)

2.Are compressible

3.Have low density

4.Are fluid

5.Diffuse rapidly

6.Consist of extremely disordered

particles with much empty space

between them; particles have rapid,

random motion in three dimensions

Heat

Cool

Heat or

decrease

pressure

Cool or

increase

pressure

Solid

Liquid

Gas

See the Saunders Interactive

General Chemistry CD-ROM,

Screen 13.2, Phases of Matter; the

Kinetic–Molecular Theory. This screen

contains an animated version of Figure

13-1.