Atomic Theory and Its Applications

Sep 10, 2024

Lecture Notes on Atomic Theory and Related Topics

Topics Covered

  • Atomic Theory
  • Mass Spectroscopy
  • Mole Conversions
  • Electron Configuration
  • Photoelectron Spectroscopy
  • Periodic Trends

Atomic Theory

  • Focus on tungsten (W), atomic number 74.
    • Atomic mass: 183.84 amu.
    • Molar mass: 183.84 g/mol.
  • Atomic Number: Number of protons; does not change.
    • Tungsten has 74 protons.
  • Average Atomic Mass vs. Molar Mass:
    • AMU measures mass of a single atom.
    • Molar mass measures mass of one mole.
    • 1 mole = Avogadro's number (6.02 x 10^23 atoms).
  • Isotopes:
    • Stable isotopes of tungsten: 182, 183, 184, 186.
    • Example problem: Finding protons, neutrons, and electrons in W-183.
      • Protons = 74, Electrons = 74, Neutrons = 109 (since 183 - 74 = 109).

Mass Spectroscopy

  • Analyzes the atomic structure by looking at protons, neutrons, and electrons.
  • Example using tungsten isotopes.
    • Remainder percentage calculation for isotopes.
    • Graphing mass-to-charge ratio vs. abundance.

Mole Conversions

  • Discussion on determining which compound has more tungsten atoms.
    • Compare WO3 vs. WO2.
    • Molar mass is key to determining the number of moles (atoms).

Empirical Formula

  • Example: Combustion of tungsten with oxygen.
    • Determine formula from mass data: W + O2 -> WO2.
    • Empirical formula calculation based on mole ratios.

Electron Configuration

  • Key Vocabulary:
    • Orbital: Region in space with up to two electrons.
    • Energy Level: Distance of electron from nucleus.
    • Sublevel: Shape of the orbital (s, p, d, f).
    • Electron Spin: Opposite spins in same orbital.
  • Sublevel Shapes:
    • s: Sphere
    • p: Dumbbell
    • d: Four-leaf clover
    • f: Complex (flower-like)
  • Block Method: Using periodic table blocks to determine electron configuration.
    • Example: Nitrogen (N) - 1sĀ² 2sĀ² 2pĀ³.
  • Photoelectron Spectroscopy:
    • Graphs showing electron configurations.
    • Peaks represent electron amounts in sublevels.
    • Closer peaks have higher ionization energy.

Periodic Trends

  • Atomic Radius: Half the distance between two identical nuclei.
  • Ionization Energy: Energy to remove an electron.
    • Higher energy means harder to remove.
  • Electron Affinity: Energy released when atom gains electron.
    • Smaller atoms release more energy.
  • Electronegativity: Atom's ability to attract electrons in a bond.
    • Critical for understanding bond types.

Trends Summary

  • Atomic Radius increases down and to the left.
  • Ionization Energy, Electron Affinity, Electronegativity increase up and to the right.
    • Trends depend on electron distance and nuclear charge.

Q&A Highlights

  • Discussion on reading and interpreting photoelectron spectroscopy graphs.
    • Isoelectronic elements and their spectral similarities.

Conclusion

  • Overview of unit structure on these topics and transition into quantum mechanics and electron behavior.