1. Chemical Properties and Changes Objectives
-Describe two examples of chemical properties
Explain what happens during a chemical change
-Distinguish between physical and chemical change

2. Do you remember what Physical Properties are???
Color
Shape
Mass
State of Matter
Length
Ductility

3. Physical properties are not the only properties that describe matter.
Chemical properties are also used to describe matter.

4. Chemical Properties
Chemical properties describe a substance based on its ability to change into a new substance with different properties.
Ex: wood burns to form ash and smoke
Chemical properties aren’t as easy to observe as physical properties.
Examples of chemical properties: flammability and reactivity

5. In the previous example, wood burns to form new substances ( ash and smoke). Therefore wood has a chemical property which is flammability.
Flammability is the ability of a substance to burn.

6. Another chemical property is reactivity.
Reactivity is the ability of two or more substance to combine and form one or more new substances.
Example when iron combines with oxygen to form rust.
So iron has a chemical property which is reactivity.

7. Open your books page 49

8. Physical properties vs. chemical properties
Physical properties can be observed! (with your eyes!) IDENTITY OF SUBSTANCE DOES NOT CHANGE!
You can see the size of the wood without changing anything about the wood.
You can observe chemical properties only in situations in which the identity of the substance could change.
You can see that wood is flammable only while its burning.

9. Characteristic Properties
The properties that are most useful in identifying a substance are its characteristic properties.
These properties are always the same.
Characteristic properties can be physical(density and solubility) and chemical(flammability and reactivity)

10. Chemical Changes
A chemical change occurs when one or more substances are changed into entirely new substances with different properties.
You can observe chemical properties only when a chemical change might occur!
Examples of chemical changes:
baking a cake
rusting

11. Open your books page 52 Figure 3

12. Clues to chemical changes
Color change
Fizzing or bubbling (gas production)
Heat
Production of light, sound, or odor.
Chemical changes are not usually reversible!