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Claremont High School 2014-2015
Physical Science

All reaction types can be divided into two
types of changes: Physical or Chemical
Physical Change:

No new substance is formed

These changes are easily reversible or
temporary

Dissolving salt in water

Melting, boiling

Mixing of two solids or liquids
Chemical Change:

A new substance is formed

These changes are irreversible or permanent

The new substance formed will have
different properties
1. The new substance has a different
appearance such as color or physical state

Example: Electrolysis of water

Reason: Electrolysis of water produces two
new substances – Hydrogen and oxygen gas.

Hydrogen and Oxygen are gases but water is
a liquid.

http://www.youtube.com/watch?v=OTEX38b
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2. A lot of heat is given out in a chemical
change.

Example:

A chemical reaction is when a substance turns
into another substance

Chemical reactions are chemical transformations.

Example: Single displacement reaction.
A + CB  AB + C
Zn + 2HCl  ZnCl2 +H2
1.
What is the difference between a chemical
and physical change?
2.
What are some examples of a chemical
change? List at least 3.

Physical or chemical change?
 The rain turned to snow…
 Marty broke a class on the bathroom floor…
 I burned my bagel!
 I fried eggs for breakfast…
 I mixed baking soda and vinegar for science
class…
 I heated sand to its melting point…

An element is a pure substance which
cannot be split up into two or more simpler
substances by physical or chemical means.
Sugar is not an element
as it can be broken down
into carbon and water.


An element consists of only one type of
atom.

An element can exist as atoms (ex: argon) or
molecules (ex: nitrogen)

Very few elements exists as atoms besides
helium and neon.

Most elements exist as molecules.
Atoms
Smallest particle
of an element and
has the same
chemical properties
of the element.
Molecules
Made up of two or
more atoms that
are chemically bonded
together.

A compound is a substance which is made up
of two or more elements chemically
combined together.
Molecules
Compounds OR
Molecules

A compound can be broken down into a
simpler type of matter (elements)

A compound can be broken down by
chemical, but NOT physical means.

Are the following substances atoms,
elements, molecules or compounds?

A mixture is formed when substances
combine in a physical way.
 Dissolving, melting, mixing

A mixture can be separated in a physical
way.
 Dissolving, evaporating, filtering, picking pieces
out with your hand

Heterogeneous mixtures are mixtures that
don’t have their parts spread evenly.

Homogeneous mixtures are mixtures where
the parts are spread evenly.

Homogeneous or Heterogeneous?
 Sugar
 Flat soft drink (no bubbles)
 Soil
 Paint
 Beach sand
 Chunky spaghetti sauce
 Aluminum foil