Physical and Chemical Changes
Physical Property
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Observable traits that do not
change the identity of the substance
Include color, shape, smell, taste,
mass, volume and density
Also include ductility, malleability,
conductivity and solubility
Can be determined without
changing a substance
Physical Property
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Density - mass/volume
Ductility – ability to be pulled into
wire
Malleability – ability to be
hammered
Conductivity – ability to pass
electric current
Solubility – ability to dissolve
Physical Change
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Any change in size, shape, form, or
state where the identity of the
matter stays the same
Ex. - Cutting a watermelon into
slices
Often easy to reverse with filtration,
magnetism, evaporation,
distillation, and centrifuge
Physical Change
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Evidence includes:
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same substance
no new substances
color change
state change
same smell, taste, texture
different volume, mass
same density
Chemical Property
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The characteristic of a substance
that allows it to change into
something different
Includes flammability, reactivity
with oxygen, and acidity
Testing for chemical properties
causes a change in the substance
Chemical Property
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Flammability – able to be burned;
combustion
Reactivity with oxygen
Acidity
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pH level
scale from 1 to 14
1 being most acidic
14 being least acidic (most basic)
Water is a 7 (neutral) on the pH scale
Chemical Change
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Happens when a substance
undergoes a change that causes it
traits to change
Ex. - digestion, photosynthesis,
paint drying, and oil burning.
New materials are formed that are
different from the starting materials
Chemical Change
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NOT easily reversed
Evidence includes:
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Release of energy – light, heat, sound
Formation of gas or solid that is NOT
the results of simple state change
Chemical Change
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Evidence includes:
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new substance
Example of Chemical Change
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Chlorine
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Added to swimming pools and drinking
water
Causes acidity
Prevents reproduction, growth and
development of algae, bacteria, protists
and insects.
Types of Chemical Reactions
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Synthesis
Decomposition
Acids and Bases
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Acids
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Sharp smell, sour taste
Corrode metals, harmful to organisms
pH between 0 and 7
Ex. - citrus fruits contain acids.
Bases
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Feel slippery, taste bitter
May also be harmful to organisms
pH of between 7 and 14
Ex. - a bar of soap is basic
Salts
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Salts are compounds of metal and
nonmetal
Formed when acids and bases react
Ex. – table salt and chalk
Energy…
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…is required for both types of
changes