EDUC Designing Learning with Technology by MikeJenny

VIEWS: 10 PAGES: 48

									       CIPS Institute for Middle School
              Science Teachers


Constructing Ideas in Physical Science


           Joan Abdallah , AAAS
           Darcy Hampton, DCPS
 Davina Pruitt-Mentle, University of Maryland
                          Session 8 Debriefing

• What do you remember from yesterday‟s
  session (no peeking at text or notes)
• What were the “essential questions” being
  asked/explored
• What conclusions did “we” decide




AAAS/DCPS CIPS Workshop           8/2-8/13       2
                          Deeper Questions


       • What deeper questions could you
         envision students asking?
       • What misconceptions or
         misinterpretations can you foresee?
       • How or what would you say?



AAAS/DCPS CIPS Workshop          8/2-8/13      3
           Deeper Questions or Possible
                Misinterpretations


“What makes light”?
“What makes energy”?
“What makes different
  colors”?


                          What would you say?


AAAS/DCPS CIPS Workshop       8/2-8/13          4
              Electromagnetic Spectrum




                                 How Roy G. BV Lost a Vowel
This was originally "ROY G. BIV", because it used to be common to call the region between blue
and violet "indigo". In modern usage, indigo is not usually distinguished as a separate color in the
visible spectrum; thus Roy no longer has any vowels in his last name.
   AAAS/DCPS CIPS Workshop                       8/2-8/13                                              5
                          Radiant Energy



                            See Handout:
                     Continuous and Line Spectra


                                            Read Aloud



AAAS/DCPS CIPS Workshop          8/2-8/13                6
                          So….
     Things are made up of atoms
     Atoms
             Protons
             Electrons
     Electrons do a lot of spinning and hopping around
      (that‟s what causes things to have certain shapes
      and textures)
     When electrons get excited, they jump from lower
      ground state to excited state and then back to rest
      again
     This jumping back and forth = radiant energy


AAAS/DCPS CIPS Workshop      8/2-8/13                       7
                   How Do you Measure Radiant Energy?

• In order to understand behavior of e-, you need to know their:
        – Velocity
        – Location
• Werner Heisenberg (highs-en-berg), German, showed that it is
  impossible to know both the exact position and the exact
  momentum of an object (e-) at the same time (Heisenberg’s
  Uncertainity Principle)
        – Can not measure where the e- is since the “nature” of measuring is
          to “move” something
        – To know location you would have to “measure” it –but when you
          measure it would effect (change) the velocity
        – Smaller something is the more uncertain the position will be after
          measuring it
        – (Δx) (Δmv)  h/4                     Need more coffee?
                 • (Δx) = change in position
                 • (Δmv) = momentum = mass x velocity (related to KE)
        – h/4 = some constant (Planck‟s constant/4)
AAAS/DCPS CIPS Workshop             8/2-8/13                                   8
                The de Broglie Hypothesis
                                       • This enabled de
• 1923, de Broglie
  (French)
                                         Broglie to predict the
• Used Planck‟s/(and
                                         wavelength of a
  Einstein) idea…that                    particle when given
  radiation is made up of                mass (m) and
  packets of energy (this                velocity.
  gave waves properties                • General Trend
  of particles)
                                          – as mass (e-)
• He wanted to prove that
                                            increases,  decreases
  particles could have
                                          – e- mass ↑  ↓
  properties like waves

AAAS/DCPS CIPS Workshop     8/2-8/13                                 9
              The de Broglie Hypothesis cont.

     • Using E = mc2 (Einstein) and E = h  (Planck)
     • Derived: mc2 = h 
     • Substituted v (general velocity) for c
     • Substituted v/  for , because the frequency of a
       wave is equal to its velocity/by its wavelength
     • mv2 = h/
     • or  = h /mv2 = h/mv


See: http://cougar.slvhs.slv.k12.ca.us/~pboomer/chemtextbook/cch9.html



   AAAS/DCPS CIPS Workshop        8/2-8/13                               10
           The de Broglie Hypothesis cont.
• From this, shown that e- stream acts in the same way
  as a ray of light

• Given credit for indicating how to predict the
  wavelength of particular electrons

• Also showed that e- have properties of both waves
  and particles = wave-particle duality of nature

• This is why you can not measure the velocity &
  location of e- at the same time

AAAS/DCPS CIPS Workshop    8/2-8/13                      11
                          Two Formulas
•  (m) X  (s-1) = c (where c =speed of light or 3.00 x 108 m/s)

• Louis de Broglie suggested that the e- in its circular path about
  the nucleus has associated with it particular wavelengths, and
  also that the wavelength of the e- depends on its mass and
  velocity

• He called this matter waves, and used it to describe the wave
  characteristics of material particles

•  = h/mv
       – mv also called momentum
       – h= Planck‟s constant 6.63 x 10-34 J.s (1 J = 1 kg m2/s2)

      Show Subscripts and Symbols                 See handout (5.2)
AAAS/DCPS CIPS Workshop              8/2-8/13                         12
                    Making the Connection

• De Broglie = e- act as
                                        • The link between
  waves (properties of 
                                          these two concepts
  and  )
                                          = h = Planck‟s
• Schrodinger = e- act                    constant
  as particles --
                                        • Wave-particle
  different  (energy
                                          duality of nature
  property) &  (mass)



 AAAS/DCPS CIPS Workshop     8/2-8/13                          13
               Wave-particle Duality of Nature


• Shows or proves that a
  beam of e- will produce                          1s _
  a diffraction pattern like                       2s_
  light patterns                                 2p _ _ _
• Bohr and Schodinger                 •   1 & 2 = shells
  called this : wave or               •   S,p,d,f = subshells
  quantum mechanics                   •   _ = orbitals
• i.e., where are we more             •   Distance between the rings =
                                          “nodes”, places where you
  likely to “find” e- at a                will not find e-
  given moment in time



AAAS/DCPS CIPS Workshop        8/2-8/13                                  14
                          Summary
 • Planck‟s hypothesis stated that energy
   is given off on quanta (photon)
   continuously
 • Bohr showed that absorption of light at
   set  correspond to definite changes in
   energy of the e-
 • Reasoned that orbits (rings) around
   nucleus must have a definite diameter
   and that e- could occupy only certain
   orbits
AAAS/DCPS CIPS Workshop     8/2-8/13         15
                          Summary cont.

• The energy absorbed when the atom was excited =
  the energy difference between orbits
• Because these orbits represent definite energy
  levels, a definite amount of energy is radiated
• The size of the smallest orbit an e- can occupy (one
  closest to nucleus), the ground state, can be
  calculated
• Energy is determined by the movement of e- between
  energy levels that are specific for each element
• The same set of energy levels will always produce
  the same spectrum

AAAS/DCPS CIPS Workshop        8/2-8/13                  16
                          To Learn More



                                           • CEA Light Tour
                                             [Local]


                                                      See Handout

                                                           From:
                                      http://cse.ssl.berkeley.edu/light/light_tour.html



AAAS/DCPS CIPS Workshop        8/2-8/13                                              17
                          Other Resources
    • Waves –Virtual Lab [Local]

    • Exploring Earth [Local] Observe the change in a
      star's spectrum as its motion changes

    • Electromagnetic spectrum - Wikipedia

    • Discovery-The Color Spectrum How does it work?
      [Local]



AAAS/DCPS CIPS Workshop         8/2-8/13                18
     But I can not see e-, so how do we know?




AAAS/DCPS CIPS Workshop   8/2-8/13              19
                          States of Matter

         • Matter- has mass, occupies space
         • Physical states of matter
                 – Solid
                 – Liquid
                 – Gas
                 – Plasma
 One of the four states of matter. (The other three are solid, liquid and gas.) Consists of
 a gas of positively charged and negatively charged particles with approximately equal
 concentrations of both so that the total gas is approximately charge neutral. A plasma
 can be produced from a gas if enough energy is added to cause the electrically neutral
 atoms of the gas to split into positively and negatively charged atoms and electrons.
 See also: The Plasma State of Matter.
 www.spacescience.org/ExploringSpace/Glossary/1.html
AAAS/DCPS CIPS Workshop                     8/2-8/13                                          20
                 Kinetic Molecular Theory of Matter

                                                Solid        Liquid                Gas
 • States:                           Own definite       Indefinite            Indefinite
         – All matter is in constant shape              shape                 shape
           motion                    Own definite       Definite              Indefinite
         – An increase in            volume             volume                volume
           temperature increases Independent            Takes shape           Takes
           motion and decreases of container            of container          shapes of
           attraction forces holding shape              (until it fills it)   container
           the matter together                                                and fills it
         – SLGP




AAAS/DCPS CIPS Workshop              8/2-8/13                                           21
            Physical vs. Chemical Properties

             Physical Properties                    Chemical Properties
    • Can be observed without                     • Undergoes changes in
      changing form                                 chemical composition
            –     Color
                                                     – Flammability or not
            –     Odor
                                                       flammable
            –     Taste
            –     Size                               – Reacts/failure to react
            –     BPo                                  with another
            –     MPo                                – Decomposes
            –     Density                            – Rusting
            –     Specific heat (Cp)
                                                     – Combustion
            –     Hardness
            –     Solubility
            –     Mass
            –     Temperature
            –     Heat capacity
AAAS/DCPS CIPS Workshop                8/2-8/13                                  22
              Properties can also be classified as:


           Intensive                             Extensive
    • Values do not                       • Depend on sample
      depend on size of                     size
      portion                               – Mass
            –    Temperature                – Volume
            –    MPo                        – Length
            –    BPo
            –    FPo



AAAS/DCPS CIPS Workshop        8/2-8/13                        23
                          Properties
 • Molecules vibrate faster when they are
   stirred-therefore, this helps them dissolve
   faster
 • When heated dissolves faster
 • At certain temperature (w/ a solid) when heat
   added, the heat breaks the bonds. Solid
   matter changes to liquid (Melting Point MPo)
 • With a solid when freezes, attractive forces
   cause molecules to lock together into solid
   state (Freezing Point FPo)

AAAS/DCPS CIPS Workshop       8/2-8/13             24
                              Liquid Changes


•     Change of liquid into vapor  evaporation
•     Change of vapor into a liquid  condensation
•     Opposite of condensation  evaporation
•     Opposite of evaporation  condensation




    AAAS/DCPS CIPS Workshop         8/2-8/13         25
                                  Changes cont.
 • As temperature falls, and the gaseous molecules slow down,
   their weak attractive forces get an opportunity to bind the
   molecules together and change the gas (vapor) into a liquid.
   When water vapor touches cool dust particles in the air,
   condensation takes place. The droplets of water, suspended in
   the air, form clouds and rain
         – Gas  Condensation  Liquid
 • The changing of a solid into a gas without becoming liquid 
   sublimation. A lot of heat is added to the solid. This added heat
   causes the molecular vibrations to become so violent that the
   molecules of the solid completely break away from each other
   and enter into a gaseous state
         – Solid  Sublimation  Gas
                  •       Ex. Mothballs, vaporization (nuclear fallout)


AAAS/DCPS CIPS Workshop                           8/2-8/13                26
                          Changes cont.
• We know that water vapor will condense on a cool
  speck of dust. If the water vapor touches a very cold
  speck of dust in the air, the gaseous water may
  crystallize without condensing first. The ice crystals,
  suspended in the air, form clouds. If conditions are
  right, these crystals may fall to the ground as snow.
        – The changing of a gas into a solid = sublimation
• By definition, sublimation can indicate going from gas
  to solid or from solid to gas…although in “chemistry”
  usually implies going from the solid state to a gas
  state.


AAAS/DCPS CIPS Workshop            8/2-8/13                  27
                      Putting It All Together

                               GAS




            SOLID           Melts                LIQUID
                            Freezes




AAAS/DCPS CIPS Workshop               8/2-8/13            28
                          Property Changes
        Physical Change                         Chemical Change
    • No new substance is                   • Involves a change in
      ever formed                             basic nature (chemical
                                              composition)
       – Tearing paper
                                            • Change in at least one
       – Sulfur & iron
                                              new substance
       – Sharpening
                                               – Sulfur & iron heated
       – Bite
                                               – Burning paper
       – Chew
                                               – Digesting
       – Breaking glass
                                               – Sour milk
                                               – Detonation

AAAS/DCPS CIPS Workshop          8/2-8/13                               29
                                  Quiz
               •     Rust                     •   C
               •     Melts                    •   P
               •     Sharpening               •   P
               •     Digesting                •   C
               •     Biting                   •   P
               •     Burning                  •   C
               •     Slicing                  •   P
               •     Detonation               •   C
               •     Souring                  •   C
               •     Breaking                 •   P


AAAS/DCPS CIPS Workshop            8/2-8/13           30
                          Break?




AAAS/DCPS CIPS Workshop     8/2-8/13   31
                                CIPS



                          • Unit 4
                            – Cycle 1
                            – Activity 1,2 & 3




AAAS/DCPS CIPS Workshop           8/2-8/13       32
                            Energy & Heat
• Physical and chemical                         Ex.
  changes are always                               Object A = 25°C
  accomplished by energy                           Object B = 20°C
  transfer                                      What happens when they are
                                                  mixed?
• The most common form of
                                                Energy will continue to transfer
  energy transform or
                                                  until the temperature of the
  change is heat                                  objects are equal.
   – Heat is a form of energy that              The energy transfer as a result
     flows between a system and                   of a temperature difference
     its surroundings                             is called heat and is
   – Heat flows from a warmer                     represented by the letter (q).
     object to a cooler one


  AAAS/DCPS CIPS Workshop            8/2-8/13                                      33
                              Energy (continued)
• If energy is absorbed = endothermic reaction
• If energy is given off = exothermic reaction
    – Match = exothermic
    – Cold pack = endothermic
• Both forms require a certain amount of energy to get started – activation
  energy
• Quantitative measurements of energy changes are expressed in joules
  (J). This is a derived SI unit
    –    Older unit = calorie
    –    One calorie (c) = 4.184 J
    –    (C) dietary unit  calorie (c)
    –    The heat needed to raise 1 g of a substance by 1°C is called specific heat
         (Cp) of the substance
 Examples: Sand and water – different Cp values
                Which gets hotter at the beach?
                Which cools down faster?
    AAAS/DCPS CIPS Workshop                       8/2-8/13                        34
                               Dietary Calories
• The heat required to increase the temperature of 1g of water 1°C =
  4.184J
• Dietary Calories (C) are 1000 times as large as a calorie (c)
• Caloric values are the amount of energy the human body can
  obtain by chemically breaking down food
• The Law of Conservation of Energy shows that in an insulated
  system, any heat loss by 1 quantity of matter must be gained by
  another. The transfer of energy takes place between 2 quantities of
  matter that are at different temperatures until they both reach an
  equal temperature

Example: An average size backed potato (200g) has an energy value of 686,000 J. How many
calories is this?
             4.184J = 1 c, 1000 c = 1 C
             686000J/4.184 J = 164,000 c
             164,000 c/ 1000 C=164C
    AAAS/DCPS CIPS Workshop                  8/2-8/13                                      35
                              Energy Transfer


         • The amount of heat energy transferred can be
           calculated by:
                 – (heat gained) = (mass in grams)(change in T)(specific heat)
                 – q = (m)(T)(Cp)
                 – T = Tf - Ti

Example: How much heat is lost when a solid aluminum block with a mass
of 4100g cools from 660.0°C to 25°C? (Cp = 0.902 J/g°C)
            q = (m)(T)(Cp)
            T = 660.0°C - 25°C = 635°C

therefore: q = (4110g)(635°C)(0.902 J/g. °C) = 2,350,000 J

   AAAS/DCPS CIPS Workshop                  8/2-8/13                             36
                          Matter

Mixture                                Pure Substance
• Most Natural Samples                 • Few naturally pure gold
• Physical combination of                & diamond
  2 or more substances                 • Only 1 substance
• Variable composition                 • Definite and constant
• Properties vary as                     composition
  composition varies                   • Properties under a
• Can separate by                        given set of conditions
  physical means



AAAS/DCPS CIPS Workshop     8/2-8/13                               37
                                 Mixture
 Heterogeneous                                Homogeneous
 • Visible difference in                      • Only 1 visible phase
   parts and phases                             – Homogenized milk
          –    Oil and vinegar                  – Air (pure)
          –    Cookie                           – Metal Alloy (14K
          –    Pizza                              gold)
          –    Dirt                             – Sugar and Water
          –    Marble                           – Gasoline
          –    Raw Milk


AAAS/DCPS CIPS Workshop            8/2-8/13                            38
                             Pure Substance
Compound
                                                Element
  aspirin, H2O, CO2
                                                  Au, Ag, Cu, H+
• Can be broken down into 2 or
                                     • Pure and cannot be divided into
  more simpler substances by
                                        simpler substances by physical
  chemical means
                                        or chemical means
• Over six million known chemical
                                     • 90 naturally occurring
  combinations of 2 or more
  elements                           • 22 synthetic
• 7000 more discovered per week
  with chemical abstracts service
• Definite-constant element                           Element
  composition            Simpler Compound
   Compound
                                                             Element
                                Element
   AAAS/DCPS CIPS Workshop           8/2-8/13                          39
                           Matter




Heterogeneous materials               Homogeneous materials




                    Solutions              Pure substances




  Mixtures                Compounds              Elements
                          CIPS




                          Unit 5




AAAS/DCPS CIPS Workshop     8/2-8/13   41
                               Subatomic Particles
                             Building Blocks of Atoms
• Proton: (+)                                                • Electron: (-)
      – 1.673 x 10-28 g                                         – Outside „e‟ cloud
      – Discovered by Goldstein                                 – 9.109 x 10-28 g (1/1839 of a
        (1886)                                                    proton)
      – Inside the nucleus                                      – Discovered by Joseph John
(credit given to Rutherford – beam of alpha particles             Thomson (1897)
    on thin metal foil experiment. Explained nucleus
    in core, made up of neutrons and protons)                       • It‟s charge to mass ration
                                                                      (e/m) = 1.758819 x 108 c/g
• Neutron: (no charge)
                                                                – c = charge of electron in
      – 1.675 x      g       10-24                                Coulombs
      – Discovered by James                                     – Millikan determined mass
        Chadwick (1932)                                           itself
      – Inside nucleus


   AAAS/DCPS CIPS Workshop                        8/2-8/13                                    42
                                           Atoms

•    Atom – smallest particle of an element that can exist and still hold properties
•    “Atomos” – Greek – uncut/indivisible. Democritus proposed that elements are
     composed of tiny particles
•    John Dalton (1808) published The Atomic Theory of Matter
    1.      All matter is made of atoms
    2.      All atoms of a given type are similar to one another and different from all other types
    3.      The relative number and arrangement of different types of atoms contained in a pure
            substance determines its identity (Law of Multiple Proportions)
    4.      Chemical change = a union, separation , or rearrangement of atoms to give a new
            substance
    5.      Only whole atoms can participate in or result from any chemical change, since atoms
            are considered indestructible during such changes (Law of Conservation of Mass)
•    Antonine Lavoier demonstrated via careful measurements that when combustion
     is carried out in a closed container – the mass of the products = the mass of the
     reactants

     AAAS/DCPS CIPS Workshop                    8/2-8/13                                       43
                          Formula Mass
            H=1                            Billy = 150
            O = 16                         Susie = 100
            H 2O                           Billy4Susie = 800
               2x1=2
               1 x 16 = 16
            Total = 18 


         H2SO4                            2CaCl2
            H = 2x1 = 2                      Ca = 2x40 = 80
            S = 1 x 32 = 32                  S = 4 x 36 = 144
            O = 4 x 16 = 64               Total 224
         Total 98

AAAS/DCPS CIPS Workshop        8/2-8/13                         44
                     Abundance of Elements in
                             Matter
  Universe                  Atmosphere     Earth’s Crust
  • H 75-91%                • N2 78.3%     • O2 60%
  • He 9%                   • O2 21%       • Si 20%
                                           • Al 6%
  Earth                     Human Body     • H2 3%
  • O2 49.3%                • H2 63%       • Ca 2.5%
  • Fe 16.5%                • O2 25.5%     • Mg 2.4%
  • Si 14.5%                • C 9.5%       • Fe 2.2%
  • Mg 14.2%                • N2 1.4%      • Na 2.1%


AAAS/DCPS CIPS Workshop         8/2-8/13                   45
             Element Names – based on
   • Geographical
     Names                              • Gods
           – Germanium                      – He (helios – sun‟s
             (German)                         corona)
           – Francium (France)          • Properties (color)
           – Polonium (Poland)              – Chlorine - chloros –
   • Planets                                  greenish/yellow
           –    Mercury                     – Iridium –iris – various
                                              colors
           –    Uranium
           –    Neptunium
           –    Plutonium
AAAS/DCPS CIPS Workshop          8/2-8/13                               46
                           Chemical Symbols
• 1814 – Swedish – Jons Jakob Berzelius
     – Symbols = shorthand for name
             • N = nitrogen
             • Ca = Calcium                     – Latin
                                                  Iron       Fe   Ferrum
     – Latin or other name                        Gold       Au   Aurum
                                                  Antimony Sb     Stibium
                                                  Copper     Cu   Cuprum
                                                  Lead       Pb   Plumbrum
                                                  Mercury    Hg
                                                    Hydrargyrum
               – German
                                                  Potassium K     Kalium
                 Tungsten   W   Wolfram
                                                  Silver     Ag   Argentum
                                                  Sodium     Na   Natrium
                                                  Tin        Sn   Stannum
 AAAS/DCPS CIPS Workshop             8/2-8/13                           47
                            Generic Nomenclature:
                             Provisional Names
• International Union of Pure and Applied Chemistry
  (IUPAC)
• Latin – Greek Names
    – 0 =nil, 1=un, 2=bi, 3=tri, 4=quad, 5=pent, 6=hex, 7=sept,
      8=oct, 9=enn
    – + ium
    – i.e.
            •   104 un nil quad ium   Unq
            •   105 un nil pentium                Unp
            •   106 un nil hex ium                Unh
            •   110 un un nil ium                 Uun
    – Most nave been given names anyway
  AAAS/DCPS CIPS Workshop              8/2-8/13             48

								
To top