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.