Atomic Structure (Lecture Outline)

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Fred J. Grieman
Atomic Structure (Lecture Outline) Classical
world of particles and waves Classical failures
blackbody radiation and
photoelectric effect Particle/wave
duality interference Setting up atomic physics
wavefunctions
probabilities
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Rutherford Planetary atom nucleus (p,n)
charge Z, most of mass electrons surrounding
nucleus Classical View Matter particles
(lumps) of mass m (we will often idealize
as localized points) E EK EP ½mv2 EP
p2/2m EP p mv momentum
Light waves (delocalized)
Electromagnetic oscillating
electric magnetic fields.
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A f(r,t) Instant in time A f(r) A0cos
(2p r/?) mathematical function for wave
?(distance) wavelength Fixed position A
f(t) A0cos (2p t?) ?(time-1)
frequency Speed of wave (distance/time) ?(distan
ce) ?(time-1) speed of light
c c0 (vacuum)
t
r
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2) Two Slit Experiment
http//vsg.quasihome.com/interfer.htm
Determining wavelength (?) from diffraction
pattern
From spacing of peaks, D h can
determine wavelength (?) of monochroma- tic light
source
Interference of light waves
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Blackbody Radiation Planck
emit
Model Vibrating oscillators that
absorb and emit energy
Perfect body only absorb At some Temp. T
Classical Large energy (short ?) oscillators
Lots of them, can continually
absorb low energy and then emit
Continually absorb energy and then emit
E
Leads to infinite energy Impossible!!!
Planck Quantum Hypothesis Oscillators cant
absorb continuously Rather absorb in chunks of
energy called quanta h? Where h is Plancks
constant h 6.626 x 10-34 Joule seconds
Important result matter absorbs emits energy
in quanta
Gives experimental result
E
?Eh?
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Photoelectric Effect Einstein
Metals absorb light energy. If enough energy,
emits an electron with Ek Classical Light of
any E(?) metal continuously
absorbs until enough to emit electron
? of electrons and their energy only
depends on intensity of light
e-
E
? work function
Doesnt happen this way! E(light) ? ? for e- to
be emitted Einstein Light as a particle comes
as a quantum Use Planck E(light) h? (depends
on frequency)
Light energy comes in quanta E h?
E
h?o ? e-s, Ek 0
h? gt ? e-s, Ek (h? - ?)
h? lt ? no e-s
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Thought experiment
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X-ray
Electrons!!!
Particles behave as Waves with de
Broglie Wavelength
Neutrons!!!