Phases of Matter Lesson: Intro

Multiple Choice

What do we already know about the states of matter?

Changes of State

Objectives

•Describe how energy is involved in
changes of state.

•Describe what happens during melting
and freezing.

•Compare evaporation and condensation.

•Explain what happens during sublimation.

•Identify the two changes that can happen
when a substance loses or gains energy.

I. Energy and Changes of State

A. From Solid to

Liquid to Gas A
change of state is
the change of a
substance from one
physical form to
another. All changes
of state are physical
changes. The
particles have
different amounts of
energy when the
substance is in
different states.

II. Melting: Solid to Liquid

A. What Is Melting?

Melting is the change of
state from a solid to a
liquid.

B. Adding Energy: When

a solid is at its melting
point, any energy added
to it is used to overcome
the attractions that hold
the particles in place.

Multiple Choice

What is called when a solid turns into liquid?

• Evalopration

• melting

III. Freezing: Liquid to Solid

A. What Is Freezing? The

change of state from a liquid
to a solid is called freezing.

B. Removing Energy:

Removing energy will cause
the particles in a liquid to
begin locking into place.

Multiple Choice

What is called when a liquid turns into solid?

• Freezing

• melting

IV. Evaporation: Liquid to Gas

A. Boiling and Evaporation: Evaporation is the change

of a substance from a liquid to a gas. Boiling is the
change of a liquid to a vapor, or gas, throughout the
liquid.

B.Effects of Pressure on Boiling Point: Earlier, you

learned that water boils at 100°C. In fact, water boils at
100°C only at sea level, because of atmospheric
pressure. Atmospheric pressure is caused by the
weight of the gases that make up the atmosphere.

Multiple Choice

What is called when a liquid turns into gas?

• Freezing

• Evaporation

V. Condensation: Gas to Liquid

A. What Is Condensation? Condensation

is the change of state from a gas to a
liquid.

Multiple Choice

What is called when a gas turns into liquid?

• Condensation

• Evaporation

VI. Sublimation: Solid to Gas

A. What Is Sublimation? Sublimation is

the change of state in which a solid
changes directly into a gas.

Multiple Choice

What is called when a solid turns into gas?

• sublimation

• Evaporation