Atomic Absorption Spectroscopy (AAS) and Energy Levels
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Questions and Answers

What is the most important step in atomic spectroscopic procedures?

  • Absorption
  • Detection
  • Spectroscopy
  • Atomization (correct)
  • What happens to the molecule during atomization?

  • It is volatilized and decomposed (correct)
  • It is diluted
  • It is ionized
  • It is condensed
  • What is the purpose of the radiation source in AAS?

  • To ionize the atoms
  • To heat the flame
  • To produce a beam of monochromatic light (correct)
  • To detect the atoms
  • What is the result of the atoms absorbing radiation in AAS?

    <p>A decrease in the intensity of the radiation</p> Signup and view all the answers

    What is the relationship between the intensity of the absorbed light and the concentration of the atoms?

    <p>The intensity of the absorbed light is directly proportional to the concentration of the atoms</p> Signup and view all the answers

    What is the equation that describes the relationship between the intensity of the radiation and the concentration of the atoms?

    <p>Log (I0/I) = a x b x c</p> Signup and view all the answers

    What is the purpose of the chopper in an atomic absorption spectrometer?

    <p>To chop the light beam</p> Signup and view all the answers

    What is the function of the monochromator in an atomic absorption spectrometer?

    <p>To separate the different wavelengths of light</p> Signup and view all the answers

    What is the function of the detector in an atomic absorption spectrometer?

    <p>To detect the absorbed radiation</p> Signup and view all the answers

    What is the read-out device in an atomic absorption spectrometer used for?

    <p>To display the results of the analysis</p> Signup and view all the answers

    Study Notes

    Atomic Absorption Spectroscopy (AAS) and Atomic Emission Spectroscopy (AES)

    • AAS is a method that uses the absorption of light to determine elements (atoms) in a sample, requiring atomization of the sample.
    • AES is a method that uses the emission of light to determine elements in a sample, also requiring atomization.

    Energy Level Diagram

    • Different atoms have different energy transition levels.
    • Energy level diagram shows valence electron transitions.
    • Atomic absorption and emission of light are associated with transitions of electrons between different energy levels.

    Absorption and Emission Spectra

    • Absorption spectra: atom absorbs light of a particular wavelength, consuming energy.
    • Emission spectra: atom emits light of a particular wavelength, releasing energy.
    • Atomic spectra: line spectra provide specificity, as each element has its own pattern due to its unique electronic configuration.

    Atomic vs. Molecular Spectra

    • Atoms: only electronic transition states, resulting in line spectra.
    • Molecules: undergo rotational, vibrational, and electronic transitions, resulting in band spectra.

    Instrument Components

    • UV-Vis Spectrometer: light source, monochromator, sample, detector, and read-out system.
    • AAS Spectrometer: light source, monochromator, atomizer, detector, and read-out system.
    • AES Spectrometer: light source, monochromator, atomizer, detector, and read-out system.

    Flame Spectroscopy

    • Flame Spectroscopy is the study of absorption/emission of electromagnetic radiation by monatomic particles in the gaseous state present in the flame.
    • Flame is used as a source of radiation in qualitative methods like flame tests.

    Flame Test

    • Observation of different colored flames can be used to identify elements:
      • Sodium: golden-yellow
      • Potassium, cesium: violet (lilac)
      • Lithium: carmine-red
      • Calcium: brick-red
      • Strontium: crimson
      • Barium, molybdenum: yellowish-green
      • Borates, copper, thallium: green
      • Lead, arsenic, antimony, bismuth, copper: blue

    Theory of Atomic Absorption

    • Atomization: a process that produces atoms in the gaseous state.
    • Atoms in the vapor state absorb radiation of a specific wavelength, promoting outermost electrons to higher energy levels.
    • The intensity of absorbed light is proportional to the concentration of atoms in the flame.

    Beer-Lambert's Law

    • Log (I0/I) = a x b x c, where:
      • a is the absorption coefficient of the element at the appropriate wavelength
      • b is the path length through the flame (standard and constant for each instrument)
      • c is the total concentration of the atom in the test solution

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    Description

    This quiz covers the principles of Atomic Absorption Spectroscopy (AAS) and energy level transitions in atoms.

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