Transcript CHEMICAL PROPERTIES

CHEMICAL
PROPERTIES
7TH Grade Science
Mrs. Hartley
CHEMICAL PROPERTIES
 Chemical
Properties describe matter
based on its ability to change into new
__matter that has different
______properties______________.
 Example: When wood is burned,
__ash_____ and ___smoke__are created.
 __Flamability_is the ability of a substance
to burn.
CHEMICAL PROPERTIES
 Reactivity:
__ is the ability of two or more
______________ to combine and form two
new _____________________.
 EXAMPLE: Iron is exposed to
______________, it rusts.
COMPARING PHYSICAL AND
CHEMICAL PROPERTIES
 How
can you tell physical properties from
chemical properties?
 PHYSICAL PROPERTIES DO NOT ________THE
IDENTITY OF THE SUBSTANCE.
 EXAMPLE: You can find the density and
hardness of wood without changing the
wood.
COMPARING PHYSICAL AND
CHEMICAL PROPERTIES
 Chemical
properties are not as easy to
observe!
 EXAMPLE: Wood is flammable only while
it is burning.
 EXAMPLE: Wood has the chemical
property of flammability EVEN WHEN IT IS
NOT BURNING!
CHARACTERISTIC PROPERTIES
 Characteristic
Properties: most useful in
identifying a substance.
 Examples:
 Density
 Solubility
 _______________
 _______________
CHEMICAL CHANGES AND
NEW SUBSTANCES
 CHEMICAL
CHANGE: When 1 or more
substances are changed into
_________substances.
 Examples:
 Fireworks
 _________________
 _________________
 _________________
WHAT HAPPENS DURING A
CHEMICAL CHANGE?
 One
way to see what happens during a
chemical change is to
_______________________________.
 You can see all the ingredients producing
a new product/substance.
SIGNS OF A CHEMICAL
CHANGE
 Change
in color or odor
 Production of heat
 Fizzing and foaming
 Sound or light being given off
 _________________________
 _________________________
MATTER AND CHEMICAL
CHANGES
 Chemical
changes change the
____________of the matter involved.
 So, most chemical changes would be
hard to ______________.
 However, some chemical changes can
be reversed by more ____________
_______________.
 EXAMPLE: ______________________________
CHEMICAL CHANGE MINI LAB
 Steel
Wool + Hydrogen Peroxide =
______________________________________
 What did you observe?
 _________________________________________
_________________________________________
_________________________________________
_________________________________________
_________________________________________
PHYSICAL VS CHEMICAL
CHANGES



Most important question to ask yourself when
trying to decide if it is a physical or chemical
change
is___________________________________________
____________________________________________
_________________________________.
The composition of an object is the type of
matter that makes up the object and the way
that the matter is arranged in the object.
LOOK AT FIGURE 5 – pg. 20
A CHANGE IN COMPOSITION
 Physical
changes do NOT change the
_________________of the substance.
 Chemical changes do ALTER the
________________________ of a substance.
 EXAMPLE:
Electrolysis:_____________________________
_________________________________________
_________________________________________
REVERSING CHANGES





Can physical and chemical changes be
reversed?
MANY ________________changes are easily
reversed.
They do not change the composition of the
substance.
BUT MOST chemical changes would be
impossible to reverse.
EXAMPLE: Fireworks, Burning a piece of wood,
____________________, _______________,
____________________. _____________________.
I CAN STATEMENTS…
I
can tell
you_____________________________________
________________________________________.
 I can tell you
_________________________________________
________________________________________.