Key Concepts

• Heating and cooling can cause materials to change characteristics, such as state, color, and texture.

• Heating causes ice to become liquid water and cooling causes condensation to form on a window, mirror, or on the outside of a glass of water.

• We can predict the changes to matter caused by heating and cooling.

Let’s Review• There are Three States of Matter

Solids• In a solid, particles are locked into fixed

positions. The particles of a a solid are moving, but they vibrate in place.

• Solids have an exact shape and volume.

• Rocks, ice cubes, desks, chairs, bowling balls, pencils are all examples of solids.

Liquids• When heat is added to a solid, its particles begin to

vibrate faster. • Eventually, its particles vibrate so much that they start

to move around each other.• The solid melts and becomes a liquid.• Since the particles in liquids can move around each,

liquids can change shape easily and be poured.• Liquids take the shape of the container they are in, but

their volume stays the same.• Orange juice, milk, water, soda, etc. are all examples

of liquids.

Gases• If heat is added to a liquid, its particles

move around even faster. • Eventually, its tiny particles move so

rapidly that they spread out in all directions as a gas.

• A gas has no definite shape or definite volume. It fills up whatever space it has.

• Oxygen, helium, carbon dioxide are examples of gases.

Changes in the States of Matter

Water clearly shows how heating and

cooling change the state of matter by melting, freezing, evaporating, and

condensing.

Changes in the States of Matter- Water

• Water can take 3 different forms:

solid, liquid, or gas.

Ice is water in the solid state.

As heat is added, it melts

into a liquid- water.

If more heat is added, the

particles move faster and

faster until they evaporate,

creating a gas.

Melting• When a solid turns to a liquid because

head has been added. – Heat melts the ice to a new state-liquid water– (other examples-Crayons, chocolate, plastic,

butter)• What happens when you leave ice on the sidewalk in the

summertime?

Evaporation• When more heat is added, a liquid turns to

a gas – As the liquid is heated and the particles move

faster, it turns to a gas.– (Ex. When the sun heats the pavement and it

dries quickly after a summer rain, puddles disappearing)

When you boil water on the stove what do you think will happen? Do you think that will always happen?

Condensation• When a gas turns to a liquid because heat

has been taken away.– Particles become cooler, move slower and

form a liquid– (Ex. When water droplets form on the outside of

a glass of cold ice water. These droplets are actually water vapor from the air that has been cooled down by the glass)

» When you wake up and there are droplets on the car’s windshield, what do you think happened? Did it get colder overnight?

Freezing• When a liquid turns to a solid because

move heat more heat has been removed.– If a liquid gets cold enough, the particles

begin to slow down and freeze. – (Ex. When water turns to ice)

Let’s ReviewIn which state of matter are the particles

most organized?

A.) Solid

B.) Liquid

C.) Gas

Elena placed 150 grams of water into the freezer. She wanted to see if freezing the water would change its mass. How will the mass of the water be affected when the water freezes?

A. The mass will be greater.B. The mass will be smaller.C. There will no longer be a mass.D. There will be no change to the mass.

Let’s Review

Which of these must happen before an ice cube can begin to melt?

A. Heat must be added to the ice cube.

B. Water vapor must form around the ice cube.

C. The air pressure around the ice cube must increase.

D. The ice cube must be separated from any other cubes.

Let’s Review

The picture shows the process of —   

A. condensation   

B. evaporation  

C. melting   

D. freezing 

Let’s Review

This diagram represents water in a container. What process is taking place?    

A. Freezing 

B. Evaporation  

C. Melting 

D. Condensation  

Let’s Review

Essential Questions

• How can heating an object change the way it looks? How about the way it feels?

• How can cooling an object change the way it looks? How about the way it feels?

• We can predict the changes to matter caused by heating and cooling.