THE ATOM (DOC)

							                               THE ATOM
                 PHYSICS IS PHUN - January 2008
S   Please take a grating
S   Please be Seated
S   Program tonight is THE ATOM
          Tonight we will discuss concepts in sub-microscopic physics.
          To do this we must use indirect experiments and models.
          Make sure you have a grating
S   The Elements, by Tom Lehrer


    ELECTROMAGNETIC SPECTRUM
D   K8-01 ELECTROMAGNETIC WAVE - MODEL
    Comment: Variety of EM waves - all obey the equation
S   c=f
S   EM Spectrum by frequency, wavelength, and photon energy (neglect now)
D   N1-05 SPECTRA - VISIBLE AND INVISIBLE
    Comment: UV using fluorescein dye, IR using thermocouple
S   Duality of Light
    Comment: photon behavior of light/EM waves - great paradox of physics
S   E=hf (NOTE: Einstein Nobel Prize for this)
S   Boiling Water and the Photoelectric Effect
D   P2-02 PHOTOELECTRIC EFFECT IN ZINC - ARC LAMP
S   EM Spectrum by frequency, wavelength, and photon energy
D   P2-05 PHOTO-RESISTOR RELAY
    Comment: operates street lamps using photoelectric effect
          Examples: photoelectric calculators, experimental car (UM)
                                                (page 2)


    ATOMIC STRUCTURE AND TRANSITIONS


S   Atomic Structure
    Review:       Atom = nucleus with electrons in orbit around nucleus
                        simple model - like planets revolving around sun
                        typical size ~ 10-10 meters
            Nucleus = protons and neutrons
                        typical size ~ 10-15 meters
                        most mass in nucleus; electrons ~ 1 part in 4000
D   P3-53 ATOMIC ENERGY LEVEL MODEL
    Comment: Higher level is less strongly bound, larger electron radius
S   Periodic Table
    Comment: Energy level structure leads to periodic table and line spectra
                  Alternatively: these are evidence of atomic energy levels
            Stable inert gases: He, Ne, Ar
            Extra electron share it: H, Li
            Lacking electron grab it: Fl, Cl
    Comment on Periodic Table of the Elements
S   Atomic Spectra – list ones to be seen here
S   Black
D   Diffraction spectrum of white light with gratings
D   P3-51 BALMER SERIES with TV
S   Hydrogen atomic transitions
    Comments:           n=1 series UV (Lyman)
                        N=2 series (Balmer) visible
                        N=3 series IR (Paschen)
S   Black
                                                 (page 3)


D   N2-02 DIFFRACTION SPECTRA - THREE SOURCES - EXPENDABLE GRATINGS
    White light, Mercury, Cadmium
    Comments: Heat creates continuous spectrum
            Atomic electron transitions create line spectra
            Discrete energy levels create discrete spectra
            All atoms and/or molecules have different spectra (structure)
    Comment: ID materials, drugs, etc.


D   N2-03 DIFFRACTION SPECTRUM OF SODIUM - EXPENDABLE GRATINGS
    Comments: mercury as “starter” - heats up sodium vapor
            Continuous spectrum due to atomic collisions
            Absorption spectrum from cooler outer vapor
S   Sodium Spectrum
    Comment: Analog to Fraunhofer spectrum of sun - helium discovery
S   Fraunhofer Absorption Spectrum
S   BLACK
D   Molecular Spectrum of I2

    Comment on spectrum of H20 and CO2 and the Greenhouse Effect



    ATOMIC PHYSICS PHENOMENA
S   ATOMIC PHENOMENA LIST
    FLUORESCENCE
S   Black
D   Fluorescein UV screen (using black light)
    Comment: UV causes photoelectric effect
            Electrons fall back to ground state emitting characteristic radiation
                                            (page 4)
D   P3-62 FLUORESCENT CHALK
    Comment: Non-fluorescent
            Colored in white light
            White in white light
D   P3-66 FLUORESCENT SOAP
    Comment: Trick used to make clothes "whiter and brighter"


    PHOSPHORESCENCE
    Comment: Phosphorescence is "delayed" fluorescence
D   P3-64 PHOSPHORESCENCE - BLACK LIGHT AND OSCILLOSCOPE
    Comment: Useful in TV and computer monitors


    APPLICATIONS
S   Applications
S   Black
    LASERS
D   P3-71 VISIBLE LASER
S   HeNe Laser Drawing
S   HeNe and LED Spectra
S   Black
    NEON SIGNS
    Comment: color depends on gas and pressure
            All "neon" signs aren't neon.
    FLUORESCENT LIGHTS
S   Cyclotron RF glow with inadequate vacuum
S   Cyclotron Ion Source glow
S   See you next time!
                            Pre-Show Demonstrations


P2-04 PHOTOELECTRIC PROPELLER
P2-06 PHOTOELECTRIC TRUCK


P3-61 FLUORESCENT LIQUIDS
P3-63 WAVELENGTH SHIFTER BAR
P3-64 PHOSPHORESCENCE - BLACK LIGHT AND OSCILLOSCOPE
P3-23 CATHODE-RAY TUBE - FLUORESCENCE EFFECT


DISCHARGE TUBES with Hand-Held Gratings
    Hydrogen, Helium, Neon, Iodine


P3-71 VISIBLE LASER
    Spectra of Light-Emitting Diodes


P3-01 PERIODIC CHART


P3-52 RESONANCE RADIATION


P2-11 INTERFERENCE OF PHOTONS
M1-11 LASER DIFFRACTION - FIXED DOUBLE SLITS


ELECTRON ORBITAL MODELS