The States and Structure of Matter by liuqingyan

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									Energy and States of Matter

             Unit 1
   Physical Science HS Credit
           Mrs. Rubel
           The States of Matter

• States of matter are the physical forms in
  which a substance can exist:
Solid (crystalline and amorphous)
Liquids (with surface tension and viscosity)
Gas (pressure, Boyle’s Law and Charles's
  Law)
        Plasma (conductivity)
                Solids
• When matter has a definite shape and
  volume. The particles are so close
  together that the atoms or molecules
  move, but not fast enough to overcome
  the gravitational attraction between
  them. Each particle is locked into place
  by the particles around it.
        2 Types of Solids
• Crystalline solids – atoms/molecules
  are arranged in repeating pattern of
  rows. Ex: diamonds, ice and iron.

• Amorphous solids –atoms/molecules
  are not in a particular order or
  organized pattern. Ex: wax, rubber.
                Liquids
• Liquids take the shape of the container
  they are in. The atoms can move fast
  enough to overcome the attraction
  between them. The volume remains the
  same, regardless of the container.
                Buoyancy
• The ability of a fluid to exert an upward
  force on an object immersed in it.
• If the buoyant force is equal to the object’s
  weight, then the object will float.
• If the buoyant force is less than the
  object’s weight, then the object will sink.
       Archimedes’ Principle
• Archimedes and the Volume of Gold

• Object will sink until the weight of the
  water displaced equals the weight of the
  object.
   How does a steel ship float?
• Bottom portion of the ship will sink until the
  weight of the ship and the buoyancy of the
  water are balanced. This is possible
  because of the compartments of air.
• Titanic vs. iceberg (guess who wins?)
        Pascal and Hydraulics
Pressure = force per unit area
                                    F
                                  P A

Pascal’s Principle states that pressure applied to a
  fluid is transmitted throughout the fluid (ex:
  hydraulics)
• Hydraulics: when liquids in a container are pressed,
  the liquids move outward, causing pressure. This
     pressure can be a force that can do work.
             Examples: dentist chair, car brakes.
         Bernoulli’s Principle
Bernoulli realized that, as the velocity of a
 fluid increases, the pressure exerted by
 the fluid decreases.
Examples: chemical sprayers (see page
 488), airplane wings
      Liquid Properties
• Surface tension – the force that acts upon the
  particles at the surface of a liquid, causing the liquid
  to form spherical drops.

Viscosity – A liquid’s resistance to flow. The stronger
  the attraction between a liquid’s particles, the more
  viscous the liquid is. Example: Honey and motor oil
  (yum!)
                   LCDs
• Liquid Crystals have characteristics of
  both solids and liquids. They will begin to
  melt at melting point, but they do not lose
  their arrangements – they retain their
  geometric order in specific directions.
• Because they respond to electromagnetic
  fields, they can be used in the displays of
  watches, calculators, etc.
                     Gases
• Gas – the matter can change both shape and
  volume. The atoms/molecules move so fast they can
  break away from the attraction from each other. As
  gases expand, there is actually empty space
  between particles.

• Pressure – The amount of force exerted on a given
  area. The more gas you have in a given area, the
  more the crowded particles collide with each other at
  a faster rate.
   Gases Fill Their Containers
• When the attractive forces between
  particles is overcome, then the
  movement/collision between particles will
  cause diffusion. Diffusion is the spreading
  of particles throughout a given volume
  until they are uniformly distributed.
  Diffusion can occur in solids and liquids,
  but most rapidly in gases.
                     Gas Laws
           (think pressure and volume)
• Boyle’s Law – For a fixed amount of gas at a
  constant temperature, the volume of this gas
  increases as it’s pressure decreases.

Example: Balloons. If you squeeze a balloon, you are
  applying pressure to the gas inside. The particles of gas
  are forced to move close together. If you let go and
  release pressure, than the gas expands in volume.
How Boyle’s Law Works
    Boyle’s Law and Weather
            Balloons
• When meteorologists release weather
  balloons, they only put a small volume of
  gas in each balloon. The balloon will
  travel to the upper layers of our
  atmosphere to get the information, where
  the air is thin.
• Partner share: How does this apply to
  Boyle’s Law?
                    Boyle’s Law
• A balloon has a volume of 8.0 L at a pressure of 90
  kPa. What will be the new volume is the pressure
  drops to 40.0 kPa?

Boyle’s Formula = P1V1 = P2V2
• P1 = 90.0 kPA          V1 = 8.0
• P2 = 40.0 kPA          V2 = ? So…

             P1V1             (90.0 kPa) (8.0 L)
•    V2 =      P2      V2 =      40.0 kPa     = 18 L
                     Charles Law
         (think temperature and volume)
• For a fixed amount of gas at a constant pressure, the
  volume of the gas increases as its temperature
  increases. The volume of gas will decrease as the
  temperature decreases.
                             Why?
When the temperature increases, the particles of gas move faster
  and expand as much as they can (increase volume). If it is
  cooler, the particles slow down and do not expand
            (decrease volume).
Charles’s Law
            Using Charles’ Law
V1      V2
T1 =     T2 (Pressure must remain constant)
A 3.0 L balloon at 10.0oC was placed in a container of ice
   water (2.0oC). What is the resulting volume?
V1 = 3.0L     T1 = 10 0oC
V2 = ?         T2 = 2.0oC
                Charles’ Law
• Absolute Zero - Temp at which...
  – the volume of a gas would equal zero.
  – all particle motion would stop.

   -273°C
     or
     0K
       Last State of Matter: Plasma

• Plasma doesn’t have a definite shape or volume, and
  the particles have broken apart.
• However, plasma has conductivity, which means that
  an electric current can go through it. Electric and
  magnetic fields can affect plasmas, but not gases.
• Natural plasmas are found in lightning, fire and in the
  aurora borealis (Northern Lights).
• The artificial plasmas created in fluorescent lights are
  created by passing electrical currents through the
            gasses.
Artificial and Natural Plasma
           Changes of State
• All changes of state are physical changes.
• The change requires a change in energy. If
  energy is removed, then the particles move
  slower (water to ice). If energy is added, then
  the particles move faster (raising the
  temperature).
• Heat, which is a transfer of energy, causes
  temperature changes, which causes a change in
  state.
      The 4 Changes of State
1)Melting Solids to Liquids – the melting point
  is the temperature when a solid becomes a
  liquid. Melting point is a characteristic property
  of a substance.
• Melting is an endothermic change, because
  energy is absorbed by the substance as it
  changes state. This energy increases the
  motion of the molecules until they can overcome
  their attractions to each other.
       The 4 Changes of State
             (continued)
2) Freezing Liquids to Solids- This is at
  the substance’s freezing point.
Remember, you don’t loose energy (it
  changes form)
Proof that freezing and melting points are
  the same……
    Heating Curve of a Liquid
When thermal energy (heat) is added, the
 liquid begins to change state. The
 freezing/melting points are equal, as are
 the points for boiling/vaporization. At 0oC,
 all energy is put into the ice to overcome
 attractive forces of particles. At 100oC,
 the water is using all energy for boiling or
 vaporization. See the graph on page 480.
Ice Water: The energy added to 0oC will melt the ice, but
it was removed at the same temperature to freeze the
water! So why doesn’t the water freeze?
        The 4 Changes of State
              (continued)
3) Vaporization: Liquids to Gases
  - boiling is vaporization that occurs when a
  substance reaches its boiling point, which
  then leads to evaporation.
   - Evaporation – vaporization that occurs at
  the surface of a liquid below it’s boiling
  point. The particles at the surface move fast
  enough to break away from the surrounding
  particles, and thus become a gas.
         Thermal Expansion
• Thermal expansion is an increase in the
  size of a substance when the temperature
  is increased.
• When the temperature of an object is
  lowered, particles slow down. The
  attraction between the particles increases,
  so they move closer together.
Thermal Expansion and Density
• When heat is added and particles begin to
  expand, then there is a increased distance
  between the particles. This expansion
  means a decrease in density.
• This is why air is heated in a hot air
  balloon. The air inside the balloon is less
  dense than the outside air, so the balloon
  will rise.
    Boiling Point and Pressure
• Question:
• You visit a friend in Denver, Colorado.
  You are cooking pasta, and you notice that
  it takes very little time for the water to boil.
  It appears to boil much faster than it did in
  Atlanta. There must be some
  relationship between the higher altitude
  and the boiling point of water.
            What is it?
        The 4 Changes of State
              (continued)
4) Condensation – Gases to Liquids
  The condensation point of a substance is the
  temperature at which the gas becomes a liquid
  and the same temperature as the boiling point at
  a given pressure.
Example: at sea level the same temperature that
  causes evaporation creates steam
  (condensation). The energy is removed
  (exothermic change) so that the molecules of the
  evaporated gas cool enough to slow down and
  clump together.
              The “5th State”
               Sublimation
Sublimation - when solids go directly into a
  gas.
 This can only occur when the atoms or
  molecules must move from being very tightly
  packed to being very spread apart (completely
  overcoming the attraction). This also requires
  energy (endothermic change).
Example: dry ice. Once heat energy is added,
  it goes from a solid to a gas.

								
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