1. Chemical Properties p. 16 -21
Chapter 1 Section 3
Vocabulary:
chemical property
chemical change

2. Chemical Properties
Chemical properties describe matter based on its ability to
change into new matter that has different properties. For example,
when wood is burned, ash and smoke are created. These new
substances have very different properties than the original wood
had.
Wood has the chemical property of flammability. Flammability
is the ability of a substance to burn. Ash and smoke can not burn,
so they have the property of nonflammability.
Another chemical property is reactivity. Reactivity is the ability
of two or more substances to combine and form one or more
new substances.

3. Reactivity with Oxygen

4. Comparing Physical and Chemical Properties
You can observe physical properties
without changing the identity of the
substance. For example, rubbing
alcohol is a clear liquid at room temp.
Chemical properties aren’t as easy
to observe. You can see that alcohol
is flammable only when it is burning.

5. Characteristic Properties
The properties that re most useful in identifying a substance are
characteristic properties. These properties are always the same
no matter what the sample is. Characteristic properties can be
physical properties such as density and solubility, as well as
chemical properties, such a flammability and reactivity. Scientists
rely on characteristic properties to identify and classify substances.

6. Chemical Changes and New Substances
A chemical change happens when one or more substances are
changed into new substances that have new and different
properties.
CHEMICAL PROPERTIES AND CHEMICAL CHANGES ARE NOT THE SAME
THING
Chemical properties of a substance describe which chemical changes
will and will not occur. For example, a substance has the ability
to be flammable or nonflammable.
Chemical changes are the process by which the substances actually
change into new substances with new properties. For example,
when a car burns gasoline, the gas actually changes into a new
substance, water and air pollution.

7. Examples of Chemical Changes

8. Signs of a Chemical Change
The number one sign that a chemical change has taken place
is a new substance with totally new properties forms.
Other signs that a chemical change has taken place are not quite as
reliable every time. They are usually good indicators, but not always.
These signs include:
a change in color
a change in odor
production of light
production of heat
production of sound
fizzing, foaming or bubbles forming
not easily reversible

9. Physical vs. Chemical Changes
The most important question to ask when trying to decide if a
chemical or physical change has happened is, Did the substance
change into a new substance with new properties?
The new substance is nothing like the substances that originally
made it up. If this is true, then you know that a chemical change
has taken place. A chemical change alters the composition, or
identity, of the substance.
Physical changes do not change the identify of the original
material. For example, water can be solid, liquid, or gas, and it
looks very different in each of its forms, but its composition, or
identity, remains the same.

10. Reversing Changes
Many physical changes are easily reversed. They do not change
the composition of the substance. For example, if you melt an
ice cube, you could easily freeze the water to make another ice
cube. Some physical changes are not as easily reversed. An example
of this would be shaving wood into sawdust. You know the sawdust
is still wood, but it is not easily reversed. The identity of the substance
is still the same.
In a chemical change, the composition of the substance changes into
a new material with totally new properties. It would be almost
impossible to reverse the chemical changes that happen when
fireworks explode even if you collected all of the materials made in
the chemical change. The only way to reverse a chemical change is
with another chemical change, and even this would be difficult to do.

11. Chemical Changes Song

12. Quiz Time! 1. What does the term reactivity mean?
It is the ability of two or more substances to combine and form
one or more new substances.
2. How is a chemical change different from chemical properties?
Chemical changes occur when one or more substances are
changed into totally new substances with new properties.
A chemical property tells whether a chemical change will happen.
3. Give an example of a chemical change that happens when you
are cooking dinner.
burning of gas when you cook in an oven or on the stove,
cooking your food

13. 4. What is the #1 sign that a chemical change has taken place?
It forms a new substance with totally new properties.
5. List three other clues that a chemical change has taken place.
color change, bubbles, fizzing, foaming, not easily reversible,
new odor, heat, light or sound given off
6. Rusting is an example of a
A. physical property
B. physical change
C. chemical property
D. chemical change D