This document discusses physical and chemical changes of matter. It defines change as altering a substance and outlines that changes can be physical or chemical. Physical changes alter the form but not chemical composition, while chemical changes create new substances through chemical reactions. The three states of matter are defined as solid, liquid, and gas, with changes in state being physical. Evidence of chemical reactions include light evolution, temperature changes, new gas formation, color changes, and solid precipitate formation.

1. Physical and Chemical Changes
of Matter

4. What is “Change”?
 It is the act of altering a substance.
 An event, NOT a trait.
Before condition  After condition.
 Can be PHYSICAL or CHEMICAL.

5. All Changes of Matter Involve Energy
being Tranfered and Transformed
 Energy always moves between the system
and the surroundings during changes of
matter.
System = the chemicals of interest
Surroundings = everything else (including
the beaker and thermometer)
 Energy cannot be created or destroyed, it can
only be transferred from place to place and
transformed from type to type (Law of
Conservation of Energy).

6. Physical Change
 Does not alter the chemical composition or
identity of the substance, only the form.
 Melting ice (change in state or phase)
 Freezing Kool-aid
 Tearing paper
 Boiling water (change in state or phase)
 Stretching silly putty
 Making a mixture (ex. Sugar water)
 Unmixing a mixture (ex. sorting)

7. States of Matter
 The 3 main states of matter: solid, liquid, gas.
 Changes in state are physical changes (no
change in composition).
 Temperature is caused by the vibrational
(kinetic) energy of atoms or molecules.
 As temperature increases, 1) solids turn to
liquids, and 2) liquids turn to gases.

8. CHANGES OF STATE

9. Definite
Shape?
Definite
Volume?
Compressible?
GAS N N Y
LIQUID N Y N
SOLID Y Y N

11. Deposition

13. States of Matter for H2O

14. Chemical Changes
 Does alter the chemical composition or
identity of a substance and makes new
substances.
 Burning paper
 Digesting food
 Rotting
 Iron reacting with oxygen gas
 A chemical change is also called a chemical
reaction.

15.  Exothermic change - heat moves out
the the system into the surroundings.
The surroundings get hotter.
System
Surroundings
System
System
System

16.  Endothermic change – Heat moves into
the system from the surroundings, so
the surroundings gets colder!
System
Surroundings
System
Surroundings
System
System
Surroundings
Surroundings
Surroundings

17. Evidence for Chemical Reaction
1) Evolution of light.

18. Evidence for Chemical Reaction
2) Temperature Change.

19. Evidence for Chemical Reaction
3) Formation of a new Gas/Bubbles.

20. Evidence for Chemical Reaction
4) Color Changes.

21. Evidence for Chemical Reaction
5) Formation of a solid precipitate.

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