Warm-Up List 5 physical properties. List 5 physical
changes.
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Chemical Properties Chemical Properties 8 th Grade Physical
Science
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What is the definition of physical property?
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Physical Property A characteristic of a substance that can be
observed without changing the substance into another substance
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What are some physical properties?
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Physical Property Examples: color, odor, shape, size, mass,
volume, magnetism, ability to conduct electric current, strength,
flexibility, texture, density, state, thermal conductivity,
solubility, ductility, malleability, melting point, boiling
point
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What is a physical change?
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Physical changes do not form new substances.
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What are some physical changes?
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Examples of Physical Changes Boiling Freezing Dissolving
Breaking Making a mixture - 2 or more types of matter (substances)
mixed together Can be separated physically All phase changes are
physical changes!
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Henry takes a cup of water and places it in the freezer. The
liquid water changes to ice. Henry thinks this change is not a
physical change, because the water changed into ice. Do you agree
or disagree? Why?
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What is a property? Property: a characteristic of a substance
that can be observed
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Two kinds of properties: Physical Properties and Chemical
Properties
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Physical Property A characteristic of a substance that can be
observed without changing the substance into another substance
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Chemical Property Describes matter based on its ability to
change into new matter that has different properties
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Flammability The ability of a substance to burn Wood has the
chemical property of flammability. When wood is burned, ash and
smoke are created.
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Reactivity The ability of two or more substances to combine and
form one or more new substances
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Iron has the chemical property of reactivity with oxygen. When
iron reacts with oxygen, it rusts.
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Video http://www.youtube.com/watch?v=uixxJtJPVXk
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Substances can have chemical properties, even if you cant
observe them. A piece of wood is flammable even when its not
burning.
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Happens when one or more substances are changed into new
substances that have new and different properties. Chemical
Change
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Chemical properties describe which chemical changes will occur
and which will not occur.
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Chemical change is the process by which substances actually
change into new substances.
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With paper, I know that it has the chemical property of
flammability without even lighting it on fire.
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Its not until I light the paper on fire that the paper has a
chemical change.
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With baking soda, I know that it has the chemical property of
reactivity with vinegar.
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Its not until I mix baking soda and vinegar that the two have a
chemical change.
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In a chemical change, the new product(s) are different from the
substances that were initially combined together.
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+ Carbon dioxide + Water
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Burning wood is a chemical change. The wood is changed to ash
and smoke.
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Signs of a Chemical Change Change in Color Production or Change
in Odor Change in Temperature Production of Precipitate (solid)
Production of a Gas (bubbling)
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Many physical changes are easily reversed. Most chemical
changes are not easily reversed.
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When determining if the change is physical or chemical, you
should ask yourself if the composition changes.
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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.
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Physical changes DO NOT change the composition of a
substance.
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Chemical changes alter the composition of the substance.
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Physical Change or Chemical Change?
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Physical The composition stays the same. Substance is not
changed, just size or shape Change can be undone. Color changes
(careful!) Changing State Dissolving Bending, Crushing, Mixing,
Cutting, etc. Chemical The composition changes. Change CANNOT be
undone. Color changes (careful!) Production of gas (bubbles)
Production/Change in odor Change in temperature Production of
precipitate
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Cracking Eggs
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Physical Change Cracking an egg separates the shell from the
insides. The substances do not change.
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Slicing Bread
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Physical Change When the bread is sliced, the bread just
changes size and shape.
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Lighting a Match
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Chemical Change The phosphorus and wood are changed into new
substances.
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Rusty Nails
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Chemical Change Oxygen in the air reacts with the metal of the
nail. This produces a new substance called rust.
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Ice Melting
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Physical Change The ice just changes from solid to liquid. The
water does not change into a new substance.
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Glass Breaking
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Physical Change The glass does not change into a new
substance.
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Boiling Water
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Physical Change When water boils, water changes from a liquid
to a gas. The identity of the water does not change.
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Mixing Lemonade Powder into Water
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Physical Change After mixing the lemonade powder and water,
lemonade powder and water are still present. Evaporating the water
separates the ingredients.
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Baking a Cake
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Chemical Change The flour, eggs, sugar, baking powder, and
other ingredients change into a new substance.
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Mowing the Lawn
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Physical Change Cutting the grass does not change the identity
of the grass.
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Fireworks Exploding
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Chemical Change Fireworks are composed of different metals,
such as copper. After ignited, the fireworks produce light, heat,
and sound.
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Melting Butter for Popcorn
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Physical Change Heating causes the butter to change from a
solid to a liquid. The identity of the butter does not change.
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Hammering Wood Together to Build a Birdhouse
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Physical Change Hammering the wood together causes the wood to
change shape. The identity of the wood does not change.
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Spoiling Food
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Chemical Change Spoiling food changes color and has a foul
odor. Bacteria, mold, enzyme action, and oxidation cause
spoilage.
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Separating a Mixture of Rocks and Sand
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Physical Change Separating the rocks from the sand can be done
by physical means. The identities of the rocks and sand do not
change.
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1.Define and give an example of a physical property. 2.Define
and give an example of a physical change. 3.Define and give an
example of a chemical property. 4.Define and give an example of a
chemical change. Exit Slip
