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Chapter 17 Classification of Matter

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Title: Chapter 17 Classification of Matter


1
Chapter 17Classification of Matter
  • Granite

2
Section 1Composition of Matter
  • Substance Either an element or a compound. They
    can be broken down into simpler components and
    still maintain the properties of the original
    substance
  • Exp. helium, aluminum, water, salt
  • Elements All the atoms in a substance are alike
  • ONE KIND OF ATOM
  • Examples graphiteall carbon atoms
  • outside of a copperall copper atoms
  • inside of a penny all zinc atoms
  • 90 elements are found in nature20 others have
    been manmade

3
  • Compounds a substance in which the atoms of two
    or more elements are combined in a fixed
    proportion.
  • TWO OR MORE KINDS OF ATOMS
  • Example water two hydrogen atoms and one
    oxygen
  • salt sodium and chlorine
  • Mixtures made up of two or more substances that
    can be easily separated by physical means
  • Example pizza and soft drinks

4
Mixtures
  • Heterogeneous a mixture in which different
    materials can be distinguished easily by the eye
    or microscope.
  • UNEVENLY MIXED
  • Example granite, concrete and dry soup mixes,
    shirts that are polyester and cotton

5
  • Homogeneous mixtures contain two or more
    gaseous, liquid, or solid substances blended
    evenly throughout.
  • EVENLY MIXED Solution
  • Example soft drinks, vinegar
  • Solution a homogeneous mixture of particles so
    small that they cannot be seen with a microscope
    and will never settle to the bottom of their
    container.

6
  • Colloids type of mixture that never settles and
    its particles are larger than those in solutions
    but not heavy enough to settle.
  • Colloid comes from the Greek word for glue.
  • Example milk
  • .

7
  • Appearance distinguishes colloid from a solution
  • Tyndall Effect the scattering of light by
    colloidal particles
  • This occurs because the particles in a colloid
    are large enough to scatter light, but those in
    the solution are not.
  • Colloids of liquids in liquids are emulsions
  • Colloids of solids in liquids are sols (when
    cooledgel)
  • Colloids of liquids or solids in gases are called
    aerosols

8
  • Suspensions some mixtures are neither solutions
    nor colloids
  • Example muddy pond water
  • If the pond water stands long enough, some mud
    particles will fall to the bottom, and the water
    clears. It is a heterogeneous mixture containing
    a liquid in which visible particles settle.
  • River deltas are a large scale examples of how a
    suspension settles.

9
Section 2Properties of Matter
  • Physical Properties
  • 1. Appearance shape, color, and state of matter,
    size
  • 2. Behaviormagnetic or high or low viscosity
  • Physical properties can be used to separate
    substances in a mixture.
  • Exp.- Magnetism separates iron from sand

10
Physical Change
  • A change in size, shape, or state of matter is
    called a physical change.
  • These changes may involve energy changes, but the
    kind of substance-the ID of the element or
    compound-does not change.
  • Exp. Gum-tear in halfstill tastes and chews the
    same.
  • Exp. Copper-heated glows red and then white but
    it is still copper
  • You can use physical changes to separate
    substances sea water can be purified to fresh
    water by distillation.
  • Distillationprocess for separating substances in
    a mixture by evaporating a liquid and
    re-condensing its vapor.
  • Two liquids with different boiling points can be
    separated by distillation.
  • Exp.- Natural oils like mint

11
Chemical Properties and Changes
  • Since burning produces new substances during a
    chemical change, flammability is an example of
    chemical change.
  • Chemical propertya characteristic of a substance
    that indicates whether it can undergo a certain
    chemical change.
  • Exp. brown medicine bottles because the drug
    may react to light.

12
Detecting a Chemical Change
  • Chemical change- a change of one substance to
    another.
  • Exp.- chili cooking unattended smell burnt odor
  • -smell of rotten eggs or the formation of rust
    are signs of a chemical change
  • -tarnished silver is also a sign of a chemical
    change
  • Using chemical change to separate to remove
    tarnish from silver place silver pot in a
    cooking pot of water with some aluminum foil in
    it and then heat the pot of water. A chemical
    reaction occurs and removes the tarnish. Tarnish
    is silver sulfide formed from sulfur compounds in
    the air!
  • This type of chemical separation is more common
    in factories.

13
Weathering- Chemical or Physical Change?
  • Physical large rocks can split when water seeps
    into small cracks, freezes, and expands.
  • Chemicallimestone does not dissolve easily in
    water except when the water is acidic, then the
    calcium carbonate reacts and changes to a new
    substance calcium hydrogen carbonate, which does
    dissolve in water.
  • Exp. White Cliffs of Dover lining the English
    Channel.

14
Conservation of Mass
  • Burning wood is example of chemical change.
  • Log does look differentash
  • Masses are different (log vs. ash)
  • But if collected all oxygen and smoke and gases
    that escaped from the burning log and measure
    their masses tooyou would find that the masses
    were equal and thus no mass was lost after all.
  • Law of conservation of mass the mass of all
    substances that are present before a chemical
    change the mass of all the substances that
    remain after the change.
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