Physical vs Chemical
Changes and Properties
Properties – what are they?
Property
• The arrangement of atoms determines
the properties of the substance
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Shape
Color
Texture
Odor
Luster
Transparency
Density
Size
Volume
Mass
Melting Point
Boiling Point
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Mass
Melting Point
Boiling Point
Freezing Point
Hardness
Resistance
Flamable
Conductivity
Magnetism
Insulator
• Will every
substance have all
these properties?
• Is the lack of a
property a property?
Physical Properties
Physical Properties
• Observations made about a substance
that doesn’t change the substance
itself
• You can stretch a rubber band, bend a
piece of wire, or break a piece of gum.
• Because you are still left with the same
substance when you are done, it is a
physical property.
Physical Properties
• Appearance:
• How would you describe a tennis ball?
(shape, color, state of matter)
• How would you describe a soft drink?
(color, state of matter, taste)
• You could also measure its volume and
temperature—these are all physical
properties
Physical Properties
• Behavior:
• Some physical properties describe the
behavior of a substance
• For instance, objects containing iron (I.e.
safety pins) are attracted by a magnet
• Think about a soft drink. If you were to
knock it over, it would spread onto the
table and floor—the ability to flow is a
physical property of liquids
Physical Changes
Physical Change
• A physical change is a change in which
a substance changes its physical
properties without changing its
chemical identity.
• These changes might involve energy
changes, but the kind of substance—
the identity of the element or
compound—does not change!
Physical Change
• Heat Curve
Physical Change
Physical Changes
• KEYWORDS:
– Freezing
– Melting
– Boiling
– Condensing
– Vaporizing
– Evaporating
– Change in size or shape
– Dissolving
Chemical Properties
Chemical Properties
• The chemical characteristics of a
substance that tend to change the
chemical identity.
• A chemical property of Fe (Iron) is
rusting.
• Limestone and acid gives off gas in the
form of bubbles –good indication that
there is a chemical change occurring.
Chemical Changes
Chemical Change
• The change of a substance into other
substances through a reorganization of
atoms.
• Chemical reactions involve chemical
changes.
Chemical Changes
• KEYWORD:
– New substance formed?
– Burning
– Change in color
– Gas given off (bubbles)
– Precipitate (solid that falls out of solution)
– Change in odor
– Rusting
Chemical Reactions
Chemical Reactions
• Bonds between atoms are formed or
broken causing substances to combine
and recombine as different molecules.
• Represented by chemical equations
• Metabolism – all of the chemical rxns that
occur within an organism
Chemical Reactions
YIELDS
2H2 + O2
Reactants
2 H2O
Products
• Atoms are neither created nor destroyed in
a chemical reaction, just rearranged!
• The Chemical Equation must be balanced!!
elements
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