Same stuff, new look

The idea

A physical change is one in which only physical properties such as shape, size and state of a substance change and no new substance is formed.

The melting ice

"I placed a cube of ice here half an hour ago. It has now become water!"

Is the water a new substance, different from ice?

• Yes, water is a new substance
• No, ice and water are the same substance

Change it, then check

Tap each card to change the thing. Then read what it says about the stuff.

Physical change

In all these cases the appearance changed, but no new substance was formed. Changes in which only physical properties like shape, size and state change are called physical changes.

Water can be solid, liquid or gas. When it moves from one state to another it is still water.

• Thing | What changed | What is it now?
• Ice cube | state and shape | still water
• Paper | shape and size | still paper
• Chalk | shape and size | still chalk
• Balloon rubber | shape and size | still rubber

Notes

A physical change is one in which only physical properties like shape, size and state change, and no new substance is formed.

Check yourself

A rubber balloon is blown up. Which statement is true?

Water in a pan turns into steam. What has changed?

Which of these can change in a physical change?

A piece of chalk is crushed to powder. How many new substances are formed?

Answer: 0

None. Crushing only changes shape and size, so no new substance is formed.

• It is still rubber, just bigger — correct. Yes! Only its shape and size changed.
• The rubber becomes a new substance. No new substance forms when a balloon is blown up.
• Nothing about the rubber changes. Its shape and size clearly change.
• It has turned into a new substance, steam. Steam is just water as a gas.
• Only its shape, not its state. Water went from liquid to gas. That is a change of state too.
• Its state, but it is still water — correct. Yes! A change of state is a physical change.
• The kind of substance. In a physical change the kind of substance stays the same.
• Shape, size and state — correct. Yes! These are the physical properties that change.
• A new substance appears. That would be a different kind of change.