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) - 1s² 2s² 2p³.
• 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.