Section 3 Three States of Matter

Chapter 17

States of Matter

States of matter are the physical states in which a substance can exist. The three most familiar states of matter are: solid, liquid, and gas.

Section 3 Three States of Matter

Chapter 17

Solids Definite Shape and Volume A solid is the state of

matter that has a definite shape and size. The particles in a solid move but not fast enough to overcome the attraction between them.

Two Kinds of Solids • Crystalline solids have an orderly three-dimensional

arrangement of particles in a pattern of rows. • Amorphous solids are made of particles that do not have a

special arrangement.

Section 3 Three States of Matter

Chapter 17

Liquids

Change in Shape but Not Volume A liquid is a state of matter that has a definite volume but takes the shape of its container. The particles in a liquid move fast enough to overcome some of the attractive forces between them.

Unique Characteristics of Liquids • Surface tension is a force that acts on the particles on

the surface of a liquid. • Viscosity is a liquid’s resistance to flow.

Section 3 Three States of Matter

Chapter 17

Gases

Change in Both Shape and Volume A gas is a state of matter that has no definite shape or volume. The particles of a gas move quickly and break away completely from one another.

The amount of empty space between gas particles can change, thereby changing the volume.

Section 3 Three States of Matter

Chapter 17

Changes of State

A change of state is the change of a substance from one physical state to another. Each state of matter can change into other states by changing the amount of energy in the substance.

Melting and Freezing Melting is the change of state in which a solid becomes a liquid when energy is added to a substance. Freezing is the change of state in which a liquid becomes a solid when energy is removed.

Section 3 Three States of Matter

Chapter 17

Changes of State, continued Evaporation, Boiling, and Condensation

Evaporation is the change of a substance from a liquid to a gas at the surface. Boiling is the change of a liquid to a gas throughout the substance. Condensation is the change of a gas to a liquid.

Sublimation: Solid to Gas Sublimation is the change of state in which a solid changes directly into a gas.