Chemistry Chapter 9: Atomic Absorption Spectrometry Quiz

Atomic Absorption Spectrometry

• The equation for absorbance (A) is: A = -logT = -log(0.65) = 0.187
• The concentration of unknown solution can be calculated using Beer's Law: A = εbc = -logT

Processes Occurring During Atomization

• Five types of processes occur during atomization: atomization, dissociation, volatilization, desolvation, and nebulization
• Examples of these processes include:
  • Na(g) formation from NaCl(g) through dissociation
  • Volatilization of solid NaCl to form NaCl(g)
  • Desolvation of NaCl solution to form Na+ and Cl- ions
  • Nebulization of solution to create aerosol

Types of Chemical Species in the Flame

• Four types of chemical species exist in the flame: atoms, excited atoms, ions, and molecules
• Examples of these species include:
  • Na(g) (atoms)
  • Na*(g) (excited atoms)
  • Na+(g) (ions)
  • NaCl(g) and metal oxides (molecules)

Selection of Flame Type

• The type of flame used depends on the volatilization temperature of the atom of interest
• Regions of the flame include: primary combustion zone, secondary combustion zone, and interzonal region

Atomic Line Spectrum

• Spectral lines are due to electronic transitions of an outer shell electron to an excited state
• The energy level diagram for atoms shows electronic energy levels
• Examples of atomic line spectra include:
  • Emission spectrum at 589 nm
  • Absorption spectrum at 330 nm

Molecular Spectra

• Molecular spectra can be obtained due to molecular rotations, molecular vibrations, and electronic states
• Energy level diagrams for molecules show electronic energy levels, vibrational energy levels, and rotational energy levels
• Examples of molecular spectra include:
  • Emission spectra
  • Absorption spectra

Beer's Law

• The equation for Beer's Law is: A = εbc = -logT
• Where A is absorbance, ε is molar absorptivity, b is path length, and c is concentration

Spectroscopy and Spectrometry

• Spectroscopy is the study of the interaction between matter and radiation
• Spectrometry is the measurement of radiation intensity as a function of wavelength
• Electromagnetic radiation (EMR) is a self-propagating wave with electric and magnetic components

Common Spectroscopic Methods

• Common spectroscopic methods include:
  • UV-VIS Spectroscopy
  • Fluorescence Spectroscopy
  • Atomic Absorption Spectroscopy (AAS)
  • Atomic Emission Spectroscopy (AES)
  • Atomic Fluorescence Spectroscopy (AFS)

Types of Atomic Spectroscopy

• There are three types of atomic spectroscopy:
  • Atomic Absorption Spectroscopy (AAS)
  • Atomic Emission Spectroscopy (AES)
  • Atomic Fluorescence Spectroscopy (AFS)