Changes of State

Changes of State

Unit 1: Matter

CHANGES OF STATE

In this lesson, you will
learn about the changes of
state in terms of the
attraction and motion of
particles.

CHANGES OF STATE

A change of state is the
change of a substance
from one physical form of
matter to another.

CHANGES OF STATE

What happens when
matter changes state?

CHANGES OF STATE

When matter changes
state, energy is gained or
lost, particle motion
changes, and energy is
conserved.

Multiple Choice

When matter changes state, energy is either _____.

• created or destroyed.

• gained or lost.

• used or stored.

• minimized or maximized.

CHANGES OF STATE

For a change in state to
occur, energy must either
be added or removed.

CHANGES OF STATE

The temperature of a
substance stays the same
until all of the substance
changes state.

Multiple Choice

The temperature of a substance changes as its temperature changes.

• True

• False

CHANGES OF STATE

When substances change
state, the motion of its
particles changes.

CHANGES OF STATE

During a change of state,
energy is conserved.

CHANGES OF STATE

How do solids and liquids
change states?

CHANGES OF STATE

Solids and liquids change
state by freezing or by
melting.

CHANGES OF STATE

The change in state in
which a liquid becomes a
solid is called freezing.

CHANGES OF STATE

What happens to the
pressure of a liquid when it
cools?

CHANGES OF STATE

When liquids cool, they
also have less pressure.

Multiple Choice

When liquids cool, they have _____ pressure.

• more

• less

CHANGES OF STATE

As the particles in a
cooling liquid slow down,
the attractions between
particles increase.

Multiple Choice

As a substance cools, the attraction between the particle _____.

• increases

• decreases

• stays the same

CHANGES OF STATE

Eventually, the particles
lock together into a solid.

CHANGES OF STATE

Different substances have
different freezing points.

CHANGES OF STATE

When a solid is warmed,
its particles have more
energy and pressure than
before.

Multiple Choice

When the temperature of a substance increases, the pressure _____.

• increases

• decreases

• stays the same

CHANGES OF STATE

The change of state from a
solid to a liquid is called
melting.

CHANGES OF STATE

What happens to the
pressure of a solid when it
is warmed?

CHANGES OF STATE

When solids warm, they
also have more pressure.

CHANGES OF STATE

As the particles in a
warming solid speed up,
the attractions between
particles decrease.

CHANGES OF STATE

Eventually, the particles
are able to slide past one
another.

CHANGES OF STATE

The melting point is where
a substance changes from
a solid to a liquid. Water
freezes and melts at the
same temperature.

CHANGES OF STATE

The process by which a
liquid or a solid changes to
a gas is vaporization.

CHANGES OF STATE

The process in which
liquid particles slowly
become gas is called
evaporation.

CHANGES OF STATE

A rapid change from liquid
to gas is called boiling.

Multiple Choice

When a liquid slowly changes state to a gas, this process is called ____.

• boiling

• evaporation

• sublimation

• deposition

CHANGES OF STATE

Air pressure affects the
boiling point of liquids.
The greater the air
pressure, the higher the
boiling point.

Multiple Choice

How does air pressure affect the boiling point of liquids?

• The greater the air pressure, the lower the boiling point.

• The lower the air pressure, the higher the boiling point.

• The greater the air pressure, the higher the boiling point.

• It does not affect it at all.

CHANGES OF STATE

The change of state from a
gas to a liquid is called
condensation.

CHANGES OF STATE

How does condensation
work?

CHANGES OF STATE

As a gas cools, its particles
lose energy and the
attraction between particles
causes the particles to slow
down and form a liquid.

Multiple Choice

What happens to the attraction between particles whenever a gas begins to cool?

• The attraction increases.

• The attraction decreases.

• The attraction stays the same.

Multiple Choice

What happens to the energy of the particles of a gas when it begins to cool?

• The energy increases.

• The energy decreases.

• The energy stays the same.

CHANGES OF STATE

Sometimes, solids and gases
can change state without
becoming liquids.

CHANGES OF STATE

When a solid changes
directly into a gas, this
process is called
sublimation.

CHANGES OF STATE

When a gas changes directly
into a solid, this process is
called deposition. Frost on
windows is an example of
deposition.

Multiple Choice

When a solid changes state directly to a gas, this process is called ____.

• evaporation

• deposition

• sublimation

• boiling

CHANGES OF STATE

When matter changes
state, it changes physically
but not chemically.

CHANGES OF STATE

When matter changes state,
only the energy of the
particles, the movement of
the particles, and the
distance between the
particles change.

CHANGES OF STATE

No matter what change
occurs to matter, it will
always have the same
mass.

That’s it.

You’re finished.