Atomic Physics II

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Atomic Physics II

• Hydrogen Atom Model

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Thomson Model
Plumb Pudding Model (1897)-  Joseph John Thomson
proposed that the atom was a sphere of positive
electricity (which was diffuse) with negative
particles imbedded throughout after discovering
the electron, a discovery for which he was
awarded the Nobel Prize in physics in 1906.
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http//galileo.phys.virginia.edu/classes/109N/more
_stuff/Applets/rutherford/rutherford2.html
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Geiger-Marsden Scattering Experiment
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Rutherford Model
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http//galileo.phys.virginia.edu/classes/252/Ruthe
rford_Scattering/Rutherford_Scattering.html
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http//galileo.phys.virginia.edu/classes/109N/more
_stuff/Applets/rutherford/rutherford.html
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Rutherford Scattering experiment
http//chemweb.chem.pitt.edu/pictures/vd02_004.htm
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http//www.chem.rochester.edu/chem131/wkshp/ruthe
rford.mov
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Bohr Atom
http//galileo.phys.virginia.edu/classes/252/Bohr_
Atom/Bohr_Atom.html
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Total Energy of the electron in the hydrogen atom
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Radius of orbital electron in the hydrogen atom
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Energy Levels on hydrogen atom
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Rydberg constant and Atomic spectrum The
frequency of the radiant energy is
where h is the Plank constant.

and
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In particular if n1 2 n2 3, 4, 5,
....... this series is known as Balmer series.
Other series n1 1 n2 2, 3, 4,
....... Lyman
n1 2 n2 3, 4, 5, .......
Balmer n1 3 n2 4, 5, 6,
....... Paaschen n1 4 n2 5, 6, 7,
....... Brackett n1 5 n2 6, 7,
8, ....... Pfund
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Example 4.1 Calculate the limiting value
(n2 ) of Paschen series with n2 gt 3 and
n1 3 and the corresponding energy.
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4.31 Emission spectra Line spectra - separate
bright lines with definite wavelength - produced
by luminous gases at low pressure in the
discharge tube - the atoms are far apart not to
interact with each other - no 2 elements give the
same spectrum
Band spectra

• Spectrum produced by molecules or molecular
  vapour
• - several well defined groups / bands of lines
• - closed together
• obtained from molecules of glowing gases heated
  / excited at low
• pressure
• - arise from the interaction atoms in each
  molecules
• e.g. blue inner cone of a Bunsen burner flame

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• Continuous spectra
• emitted by hot solid and liquid also by hot gases
  at high pressure
• atoms are so closed that interaction is
  inevitable
• - all wavelengths are emitted

• The Absorption Spectra
• line, band, continuous spectra are again obtained
• when white light passes through a cooler gas or
  vapour, the atom
• absorb the light of the wavelengths which they
  can emit and then
• re- radiate the same wavelengths almost at once
  but in all directions
• - dark lines occur against the continuous
  spectrum of white light
• exactly at those wavelengths which are present
  in the line
• emission
• spectrum of the gas or vapour
• e.g. absorption spectrum of iodine vapour

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Suns spectrum the Fraunhofer dark
lines prescence of a layer of cooler gas round
the sun absorption spectrum
http//tycho.bgsu.edu/laird/phys655/class/IC.html
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END
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http//micro.magnet.fsu.edu/electromag/java/ruther
ford/