Physical changes alter the form or appearance of a substance but do not change its chemical identity, allowing it to be changed back. Chemical changes cause the identity of the substance to change as it reacts to form new substances that cannot revert to the original. Key signs of a chemical change include production of a gas, change in color or solid formation, and changes in temperature or energy during the reaction.

1. Physical and Chemical Changes

2. Concept of Change
● Change: the act of altering a
substance

3. Physical Property
● A physical property is a characteristic of
matter that can be seen and measured.
◆Examples:
•

4. Chemical Property
● A chemical property is a characteristic
of matter that influences the reactivity
with other substances.
◆Example:
• Ability to rust
• Flammability
• Reactions with acids

5. Is it a Physical or Chemical Property?
Change Physical Chemical
A round ball
Reacts with acid
Catches on fire
Brown eyes
Rusting nail

6. Physical Change
● Physical change: a change that alters
the form or appearance of a
substance. It can be changed back.
◆Water in its different states
◆Dissolving a substance
◆

7. Chemical Changes
● Chemical change: a change that occurs
causing the identity of the substance to
change, a new substance is formed and
cannot be changed back
◆Burning something
◆Cooking something
◆Rotting
◆Souring
◆Digesting food
◆Reacting with other substances

8. ● A chemical change is also called a
chemical reaction.

9. Chemical Changes Cont’d
● How to detect a chemical change:
• A gas is produced (you see bubbles)
• A solid may be produced
• Color change
• Formation of a precipitate - a solid deposited
from a solution
• Change in temperature and energy

10. Is it Physical or Chemical?
Change Physical Chemical
Melting cheese
Burning wood
Milk souring
Tearing up paper
Bicycle rusting

11. ● Physical and Chemical video