Unit 2.4

Thermal Energy and States of

Matter

States of Matter

All matter is made up of tiny particles that are too

small to see.

Matter comes in 4 different forms called states.

State – a form of matter

The 4 states of matter are solid, liquid, gas, and

plasma.

States of Matter - Solids

Solids have a definite shape and volume.

Their particles are arranged in a pattern. They don’t

move around, but they vibrate in place.

States of Matter - Liquids

Liquids have a definite volume, but they take the

shape of whatever container they are in.

Their particles move around and flow over each

other.

States of Matter - Gases

Gases do not have a definite shape or volume.

Their particles move fast and free, bumping into

each other until they are spread out in all directions.

States of Matter - Plasma Plasma is the most common state of matter in the

universe comprising more than 99% of our visible

universe and most of that not visible.

Plasma occurs naturally and makes up the “stuff” of

our sun, the core of stars and occurs in quasars, x-ray

beam emitting pulsars, and supernovas.

On earth, plasma is naturally occurring in flames,

lightning and the auroras.

Plasma is an extremely high energy state of matter

with no definite shape or volume

States of Matter – Comparison Chart

Matter comes in four states. Work with a partner.

Properties (shape

and volume) Examples

Solids

Liquids

Gases

Plasmas

Changes of State

Matter changes states when THERMAL

ENERGY is ABSORBED or RELEASED.

HEAT makes particles in matter speed up which

causes them to change states.

Cold particles move slower.

This is a graph of the temperature of water

that starts as ice and ends up as steam.

Temperature

Thermal Energy

Little molecule

movement

solid liquid gas

Increase in thermal energy

Increase in thermal energy

Decrease in thermal energy

Decrease in thermal energy

melting evaporation

condensation freezing

Some molecule

movement Lots of

molecule movement

Particle Movement and Phase Changes

Vocabulary Connections

Melts

Boiling Point Melting Point

Boils

Freezing Point

Condenses Freezes

Condensation Point

Solid Liquid Gas

Vocabulary Connections Melting – when a solid is turning into a liquid.

Melting point – when a solid has turned into a liquid.

Boiling – when a liquid is turning into a gas.

Boiling point – when a liquid has turned into a gas.

Vocabulary Connections Condensing – when a gas is turning into a liquid.

Condensation point – when a gas has turned into a liquid.

Freezing – when a liquid is turning into a solid.

Freezing point – when a liquid has turned into a solid.

Vocabulary Connections

Sublimation – when a solid turns directly into a

gas – Dry Ice

Quick Check: What is each arrow pointing to?

Temperature

Heat Energy

1

3

5

2

4

6 7

8

9 10 11

Thermal Expansion The particles that make up matter move more when heat

is added.

When they move more, they spread out.

When they spread out, the matter they are part of

expands.

Thermal Expansion – the expansion of matter when it is

heated

Thermal Expansion Sidewalks that are built with thermal expansion in mind

don’t crack as much.

Thermal Expansion Bridges are built with ‘joints’ so they don’t crack when the

temperature changes.

Thermal Expansion

As the thermal energy of matter increases, its

particles spread out and the substance expands. A

bimetallic strip in a thermostat contracts or expands

depending on whether it is cooled or warmed.