Physical Changes

Structure of water

Structure of ice

Structure of steam

When a physical property (like the phase of water) is altered we called it a

PHYSICAL CHANGEIn other words: A physical change involves a change in physical properties (shape, size, density, etc.)

It takes a physical change to change water to steam, or ice to liquid.

Physical Changes

Physical Changes

• Physical Changes: only the phase changes, the substance does not.

• Physical changes usually change the size or shape of the substance.

• Physical changes can go back to original phases.

Physical Changes

Examples of physical changes include: Melting Point

The ice cream is melted but it is still ice cream. It still tastes like ice cream.

Physical ChangesExamples of physical changes include: Shape

The shape of the wood changes when it is made into a desk, but it is still wood.

Physical ChangesExamples of physical changes include: Freezing Point

The glass of water is frozen, but it is still water (H20)

Physical Changes

Physical Changes can be caused by changes in energy.

Physical Changes

Physical Changes can be caused by changes in energy.

Chemical Changes

Chemical Changes

Chemical Change: a change that creates a NEW material. (A change in chemical properties)

The original materials are changed into something different.

Typically irreversible (can’t be changed back)

Chemical Changes

Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.

Chemical ChangesExamples of chemical changes include: burning

(flammability)

Once the wood is burned, it is changed forever.

Chemical ChangesExamples of chemical changes include: rusting

(oxidation)

The rusty spoon cannot be changed back.

Chemical ChangesExamples of chemical changes include: cooking

Once the egg is fried, it can not be changed back to the raw egg.

Physical vs. Chemical Changes

Let’s Summarize• All matter has physical

properties and chemical properties.

• Physical properties can change, but the structure of the matter does NOT change

• Chemical properties lead the way to chemical changes.

• Chemical changes make new substances.