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Classification of Matter

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Title: Classification of Matter


1
Classification of Matter
  • Mixtures
  • Chemical and Physical Properties Changes
  • Separation Techniques
  • Endothermic Exothermic Energy

2
Pure Substances
  • These things have a constant composition
    throughout. A sample can be taken from any part
    of the object and it will always have the
    properties.
  • Ex hydrogen gas, water, any element from the
    periodic table

3
Elements
  • An element is a substance that cannot be broken
    down into simpler substances.
  • An element has a fixed composition because it
    contains only one type of atom.

4
Compounds
  • A pure substance composed of two or more elements
    joined in a fixed proportion.
  • Compounds can only be broken apart by some
    chemical means. Someone cannot pour two glasses
    of water from the same pitcher of water and have
    hydrogen in one glass and oxygen in the other
    glass.

5
Mixtures
  • A mixture is a combination of substances that
    combine and keep their own properties. The
    substances can be taken apart by physical means.
    The properties of mixtures can vary because the
    composition of a mixture is not fixed.

6
Mixtures
  • There are two types of mixtures
  • Homogeneous
  • Heterogeneous

7
Homogeneous Mixtures
  • Homo meaning same reminds us that homogeneous
    mixtures are the same elements and compounds
    throughout the mixture. One can take a sample
    from anywhere in the mixture and get the same
    results.
  • Ex Salt water (liquid) Brass (Cu and Zn)

8
Heterogeneous Mixtures
  • Hetero meaning different reminds us that
    heterogeneous mixtures have different elements
    and compounds scattered throughout the substance.
    When a sample is taken from different locations
    within a mixture different elements and compounds
    can be found.
  • Ex pizza , concrete

9
Putting it all Together
Matter Has mass and takes up space
Pure Substance Definite Composition
Mixture Variable Composition
Compound 2 or more kinds of atoms
Element One kind of atom
Homogeneous Evenly mixed
Heterogeneous Unevenly mixed
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10
Solutions, Suspensions, Colloids
  • Solution when substances dissolve and form a
    homogeneous mixture Ex water and salt
  • Suspension heterogeneous mixture that separates
    into layers over time Ex sandy water
  • Colloids some particles that are intermediate
    in size between the small particles in a solution
    and the larger particles in a suspension dont
    separate into layers. Ex fog

11
Physical Properties
  • Properties of a compound or element that can be
    tested or observed without changing the identity
    of the substance.

12
Examples of Physical Properties
13
Physical Changes
  • A change in size, shape, or state of matter. The
    changes do not alter the substances in the
    material.
  • Ex when you drop a piece of chalk and it breaks,
    you change the size of the chalk but you still
    have chalk.

14
Using Physical Properties Changes
  • When a scientist is given a sample of a white
    powder and asked to identify it the physical
    changes and properties will help to do so.
    He/she would not want to alter the powder with
    chemical changes and therefore test for physical
    properties and changes of substances that are
    known to be white powders.
  • Ex distinguishing between baby powder, flour,
    and powdered sugar

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15
Separation Techniques
  • When different elements and compounds are mixed
    together, its not always a good thing.
    Scientists want to separate the elements or
    compounds from one another. In order to do so,
    they have to perform certain separation
    techniques based upon chemical and physical
    properties of the substances.

16
Density
  • When objects have different densities they can be
    separated layer by layer. Water is more dense
    than oil and it settles on the bottom of the
    container. An oil layer forms on the top of the
    container. Oil can then be suctioned off of the
    layer of water.

 
Oil
Water
17
Particle Size (Filtration)
  • Just like playing in the sand at the beach, a
    sifter can be used to separate particles based
    upon their size. The bigger particles remain in
    the sifter while the smaller particles fall
    through the holes.

18
Solubility
  • Different compounds are soluble in different
    solutions. Mixing the compounds in the liquid
    will create a solution and allow one compound to
    be rinsed from the unknown. Water is often the
    liquid used for this process.

19
Boiling and Melting Points
  • When two liquids are mixed together one way to
    separate them is to either freeze them. If one
    has a higher freezing point than the other, it
    will begin freezing leaving the other liquid
    behind. The same holds true for two solids. If
    one has a lower melting point, it will begin
    melting leaving the other substance as a solid.
    This is known as distillation.

20
Chemical Properties
  • A characteristic of a substance that indicates
    if it can undergo a certain chemical change.
  • Examples of Chemical Properties
  • Flammability a materials ability to burn in
    the presence of oxygen.
  • Reactivity how easily a substance combines
    chemically/reacts with another substance.

21
Questions to Check for Chemical Properties
  • 1. Does it burn in air?
  • 2. Does it decompose when heated?
  • 3. What happens when it is placed in acid?
  • 4. What other chemicals will it react with?
  • 5. What substances are obtained from a reaction?

22
Chemical Changes
  • A change of one substance in a material to a
    different substance. A distinct odor is produced
    when these changes occur.
  • Ex fireworks exploding, matches burning, metal
    rusting

23
Signs of Chemical Changes
  • Production of a gas - The foaming of an antacid
    tablet in a glass of water.
  • A Change in color - Rusting iron on a car.
  • Formation of a Precipitate adding vinegar to
    milk.

24
Endo- Exothermic Reactions
  • When a chemical or physical change occurs there
    is energy present. The energy is either absorbed
    or given off as the change occurs.

25
Endothermic Changes
  • Endothermic- heat energy is taken in or absorbed
    during a reaction.
  • Ex Photosynthesis - a plants food process
  • Energy H2O CO2

Sugar O2
26
Exothermic Changes
  • Exothermic- reaction that releases heat
  • Ex Metabolism releases energy when food is used
    by living cells

Sugar O2 H2O CO2 Energy
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