2.1 Observable Properties of Matter
Ms. Wells, Science
Property Types
• Physical: properties
that can be observed
without changing the
IDENTITY of the
matter
• Chemical: property of
a substance that
changes it into a NEW
substance (changes the
identity of the
substance)
Examples of Physical Properties
• Volume, mass, color, texture, shape and
density
• Great example:
• Stretching a rubber band may change its color
and shape, but its still made of rubber and is
still a rubber band!
More about Density
• Density = amount of
matter (mass) in a
certain amount of
space (volume)
• Density is constant
(does not change for
one substance)
• Different substances =
different densities
U.S. Population Density
Calculating Density (D)
• Formula: D = m / V
• Mass (m) = kilograms (kg) or grams (g)
• Volume (V) = cubic centimeters (cm3)
• Sooo…. Units for density are g/ cm3
• Said “grams per cubic centimeters”
The Clay Example:
Density = Constant
• You have a 200g piece
of clay with volume of
100 cm3
• V = 200g/100 cm3
• V = 2 g/cm3
• If you break it in half,
you have 2 pieces of
clay that are 100g and
50 cm3 each
• V = 100g/50cm3
• V = 2 g/cm3
• SAME DENSITY!
Examples of
Chemical Properties and Changes
• Describe how substances
form into new substances
• Examples: rusting,
combustibility (burning),
tarnishing, sometimes
cooking, etc.
• Chemical REACTIONS
= Chemical Changes
Physical Changes
• Any change that does not change the actual
substance itself
• Changes in states of matter are physical (melting
ice, etc.)
• Other examples:
• Breaking an object
• Wool on a sheep
or a wool sweater
is still wool
Signs of a Chemical Change
• Odor – new smell
(rotting meat, burning
smell)
• Temperature change –
log goes from wood to
ash, feel the heat!
• Color change – not
always chemical, but
often
• New solids from
liquids (called
precipitates) – clams
make shells by mixing
seawater substances
and substances in their
bodies
Pictures of Chemical Changes
• Precipitates
forming (new
solids from
different liquid
substances)
Pictures of Chemical Changes
• Water and salt of
sweat reacts with oils
and substances on
your skin = body odor
THE END OF 2.1
Properties of Matter
in
Matter and Energy