Page 57 - York Global Science 6 - Physical Science

Physical Science

Let’s Learn

Materials change all around you.

These changes can be grouped into physical or chemical changes.

Physical Changes
Physical changes are a change in size, look or shape. The material is still

the same, but it is in a different form.
A change in state is a physical change because the particles do not
change, but how they are arranged does change. For example, the same

water molecules can be a solid, a liquid or a gas.
Physical changes are often reversible. No new materials are formed.

Chemical Changes
When a chemical change happens, the particles inside the original material

change to make a new material.
These changes are permanent and cannot be reversed.

You can look for signs to see if there was a chemical change.
These signs tell you that a new material has been made:

• Is there a colour change?

• Are there any bubbles?
• Is there any smoke or a smell?

• Is the material hot, or is there any light or sound?

If you can answer 'yes' to any of these questions, there is a very good
chance that a chemical change has taken place.
Rusting is a chemical change that happens when iron particles mix with

water and oxygen to make a new material. The new material is called iron
oxide (rust). The iron oxide is a different colour to the original material and
has different properties. This change is irreversible.

57