Atomic Spectroscopy Laboratory

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Atomic Spectroscopy Laboratory

• Science Engineering Magnet High
• Mr. Puckett

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Atomic Emission Spectroscopy Laboratory

• Problem How much energy is contained in the
  quanta between the different levels of excited
  electron energy orbitals? And what are the
  frequencies and wavelengths of the energy?
• Hypothesis The amount of energy given off is
  calculated by the colors of the quanta of light
  given off when the electrons cascade from upper
  energy levels to the natural ground state.

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Introduction and theory

• Atomic Spectroscopy is the analytical measurement
  of the quantum energy level jumps of different
  electron energy states.
• It is a spectral analysis of the colors
  (frequencies or wavelengths) that an atom gives
  off when it changes energy levels.
• Formulas c ?f and 1/ ? R(1/nf2 1/ni2)
  where R 1.097 x107 m-1 and n is the orbital
  of the energy state.
• The shortcut formula is ?E Ef Ei E2 E1
  where E -13.6 eV / n2 , then E hf.

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Atomic Emission Spectroscopy

• In this technique, the atoms are heated up to the
  point that the thermal energy promotes the
  electron up to an excited energy level and then
  measures the color (wavelength) of light that is
  given off when the electron collapses back into
  the ground state. You are looking into the atom

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Einstein proposes Quanta Energy Levels of
Electrons

• Einstein also proposed that electrons, besides
  emitting electromagnetic radiation in quanta,
  also absorb it in quanta.
• Einstein's work demonstrated that electromagnetic
  radiation has the characteristics of both a
  wave--because the fields of which it is composed
  rise and fall in strength--and a
  particle--because the energy is contained in
  separate "packets." These packets were later
  called PHOTONS.

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Energy Orbitals of the Electrons

• Electron energy orbitals are the regions where
  there is the greatest chance to find them as
  clouds

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Photon Energy Emitted out of the Excited Level
Electrons

• When the electron absorbs the energy, it is
  promoted to the higher energy orbital.
• Nature wants the electron to go back to the
  ground state level (stability and entropy
  reasons) and give the energy back off at
  frequencies that are unique for that atom at that
  level of energy.

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Materials and Procedures

• Materials
• 1. A hand held spectrometer.
• 2. A Fluorescence gas element tube with
  Hydrogen.
• Procedures
• 1. Turn the tube on to glow with lights reduced
• 2. View the light through the spectrometer
• 3. Record the emission lines as 102 nm.

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Emission Spectroscopy Examples
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Energy Level Transitions of Electrons
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Energy Levels Chart Example

• Notice the many different pathways photon energy
  release can take back to ground state.

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Results

• The results are a combination of measured visual
  colored spectral lines and the calculated energy
  levels for the electrons.

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Orbital Energy for the Atomic Hydrogen
Spectroscopy
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Frequency and Wavelength of Emitted Photons
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Error Analysis

• The main source of error in this experiment is
  the angle of the spectrometer in relation to the
  light tube. This angle can produce numerical
  results that vary as much as 100 nm. Over a
  hydrogen spectrum at 410 nm this would be 100/410
  x 100 24.4 error down to 16 at 656nm.
• To correct the error a computerized spectrometer
  could be used to obtain more accuracy.

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What YOU Learned in this lab

• Students will supply the answer to this.
• Should be at least half a page and be a synopsis
  of the experimental theory and results with
  quantification.