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Changes in Matter-Physical Properties

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									Physical Science
  Changes in Matter
    Benchmarks
     IV.2.MS.1
     IV.2.MS.2
     IV.2.MS.3
                Benchmarks
   Describe common physical changes in
    matter: evaporation, condensation, thermal
    expansion, contraction. (IV.2.MS.1)

   Describe common chemical changes in
    terms of properties of reactants and
    products. (IV.2.MS.2)

   Explain physical changes in terms of the
    arrangement and motion of atoms and
    molecules. (IV.2.MS.3)
            3 States of Matter
   There are 3 major states of matter, they
    are…
     Solids
     Liquids
     Gasses


    In all three states of matter, molecules are
      in constant motion.
And yet another phase of matter…
   Plasma is another phase of matter that is
    sometimes recognized by scientists.
       It is a state above the gas phase.

       Click the link to see another explanation of the
        states of matter.
          http://www.chem4kids.com/files/matter_states.html
                 Solids
 In a solid, relatively strong forces are
  exerted between the molecules, so the
  molecules of the material vibrate
  slowly.
 Solids, therefore, have a definite shape
  and volume.
                Liquids
 When heat energy is added, the
  molecules vibrate faster as they absorb
  the energy.
 At the melting temperature of the
  material, the molecules have gained
  enough energy, so that they can slip
  and slide past each other.
 The material is now a liquid.
                Gasses
 Liquids still have a definite volume, but
  take the shape of their container.
 When more heat energy is added, the
  motion of the molecules within the
  liquid increases, until some of the
  molecules overcome the forces,
  becoming a gas.
 The liquid has now evaporated to a gas.
      The reverse is also true
 Gas molecules are separated by
  relatively great distances and move
  about freely.
 Gases take the shape and volume of
  their container.
 Conversely, when enough energy is
  lost from gas molecules, they
  condense into the liquid phase.
                     Condensation                Freezing

                                    Contract


          more heat energy                                    less heat energy
          +E                                                                   -E
          warmer              States of Matter                         colder




Plasma         Gas                   Liquid                     Solid               BEC
            (water vapor)              (water)                     (ice)
         No definite shape        No definite shape           Definite shape
         No definite volume       Definite volume           Definite volume




                    Evaporation                     Melting
                                    Expand
           Thermal Expansion
   As a solid is heated, particles move faster
    and faster and vibrate against each other
    with more force.

   As a result, the particles spread apart slightly
    in all directions and the solid expands.

   The same effect also occurs in liquids and
    gases.
          Thermal Expansion
   Almost all matter expands as it gets
    hotter and contracts as it cools.

   This characteristic of matter is called
    thermal expansion.

   This happens because in a solid, forces
    between the particles hold them
    together.
             Thermal expansion
   Since this phenomenon
    occurs in bridges,
    expansion joints allow
    bridges to expand in warm
    weather without cracking.
Can you imagine the
 effect that thermal
 expansion and
 contraction might have
 on our roads?
      Heat and Phases of Matter
   Heat affects
    the phases
    of matter.
    View this
    video clip to
    see how.
                 Introduction
   There are two types of properties of
    matter, they are physical properties and
    chemical properties.

   There are also two types of changes in
    matter they are physical changes and
    chemical changes.

   Let’s talk about physical properties first.
          Physical Properties
   A physical property is any
    characteristic of a material that one can
    observe easily without changing the
    substances that make up the material.

   Every substance has physical
    properties that distinguish it from other
    substances.
               Physical Properties
   Physical property examples…
          shape
          Size
          Color
          Smell
          Temperature
          Volume
          Density
          melting point
          boiling point
          state of matter.
         Physical Changes
 A change in physical properties is
  called a physical change.
 Physical changes do not alter the
  identity of a substance.
 Pounding, pulling, cutting, dissolving,
  melting, or boiling do not produce a
  new substance with new properties, so
  they are all physical changes.
    Physical Change Example
 For example if you take a piece of
  paper and tear it into pieces you still
  have paper. It may be smaller, but it’s
  still paper.
 You could dye the paper and make it
  another color, but it’s still paper.
 You have only changed it physically.
             Physical Changes
   When trying to identify a physical change,
    it is important to know that physical
    changes can be reversed.

   For example…
        Pieces   of paper can be reformed into a new whole
         sheet.
        Ice can be melted, or boiled and then refrozen.
    Physical Changes of Water
Freezing-liquid to a solid; this change requires
  cooling
Melting-solid to a liquid: this change is speeded up
  by heating.
Condensation-gases change to a liquid; this
  change requires cooling.
Vaporization/Evaporation-liquid changes to gas;
  this change is speeded up by heating.
Sublimation-gas changes to a solid or a solid
  changes to a gas without passing through the
  liquid state (e.g., dry ice, solid to gas)
       What Do You Think?
 Can you name
  this physical
  change of water?
 Here’s a hint: The
  water is changing
  from the gas to
  the liquid phase.
       What Do You Think?
 Can you name
  this physical
  change of water?
 Here’s a hint: The
  water is changing
  from the liquid to
  the gas phase.
                 Review Video
   That was a lot of
    information. Let’s
    review physical
    properties and
    physical changes
    with a look at this
    video clip on
    states of matter.
    (18 min)
    Chemical Properties/Changes
   Substances
    can change
    their
    identities,
    for example,
    fireworks
    explode,
    Chemical Properties/Changes
   matches
    burn
    Chemical Properties/Changes
   Food cooks
    Chemical Properties/Changes
   And iron
    rusts
    Chemical Properties/Changes
   Burned toast, burned soup, and burned
    steak all smell burned. The smell is
    different from the smell of bread, soup, or
    steak.

   The odor is a clue that a new substance
    has been produced.
             Chemical Property
   A chemical property
    is a characteristic of
    a substance that
    indicates if it can
    undergo a certain
    chemical change.

   Click the picture for a
    video clip about
    chemical properties.
            Chemical Change
   A change of one substance in a material to a
    different substance is a chemical change.

   In some chemical changes a rapid
    production of energy, such as the production
    of heat, light, sound or gas bubbles occur.
    These things indicate that a chemical change
    has occurred.

   Burning and rusting are chemical changes
    because different substances are produced.
                Chemical Change
   A baked cake no longer resembles its
    ingredients of flour, eggs, butter, and sugar,
    because the reactants have undergone a
    chemical change.




                                                     product
          reactants


   A chemical reaction is simply breaking substances (reactants) apart
    and making new ones (products) from the pieces.
            Chemical Changes
   When trying to identify a chemical change,
    it is important to know that chemical
    changes can NOT be reversed.

   For example…
       A   cake can not be broken down into eggs, sugar,
         flour, and butter.
        You can not un burn a piece of wood.
          Chemical Reactions
   Those ingredients have been changed
    by a chemical reaction.

   A chemical reaction is simply breaking
    substances (reactants) apart and
    making new substances (products)
    from the pieces.
          Chemical Reactions
   Whenever a chemical reaction takes
    place, new substances, the products,
    are made.

   These have very different properties
    from the original starting materials, the
    reactants.

       reactant + reactant = product
         Chemical Reactions
   This process involves the
    rearrangement of atoms and molecules,
    and the making and breaking of
    chemical bonds.
               Closed System
   The mass remains constant, because a
    chemical reaction is a closed system and no
    matter is lost.

   Closed system: a system in which the total mass
    of each element in the system remains constant
    before as well as after any kind of chemical or
    physical change.

    No matter is ever created or destroyed during
    the change.
            Chemical Changes
   Here’s a video
    clip that may
    explain
    chemical
    changes more
    clearly.
    Physical & Chemical Changes
   Click the links to hear a science guys song
    on…
       Physical Changes


       Chemical Changes

								
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