Lecture on Bonding, Hybridization, and Molecular Geometry

BH3 and Hybridization

• BH3 Lewis Structure
  • Non-octet molecule.
  • Predicted 120° bond angle based on VSEPR theory.
• Hybridization of BH3
  • Three electron domains on boron.
  • Hybridization involves 2s and two 2p orbitals.
  • Forms degenerate sp2 hybrid orbitals.
  • One 2p orbital remains unhybridized.
  • Results in three sp2 hybrid orbitals at 120° angles.
• Valence Bond Theory
  • Use sp2 hybrid orbitals to form sigma bonds with hydrogen.

Methane (CH4) and Water (H2O) Hybridization

• Methane Hybridization
  • Four electron domains.
  • Hybridization of orbitals: sp3.
  • Forms a tetrahedral configuration.
  • Tetrahedral bond angle is 109.5°.
• Water Hybridization
  • Also sp3 hybridized.
  • Starting bond angle 109.5°, but electron pairs reduce it to 104.5° due to repulsion.

Expanded Octets and Complex Molecules

• Five Electron Domains
  • Consideration of 3d electrons for hybridization.
  • Formation of sp3d hybrid orbitals.
  • Trigonal bipyramidal geometry.
• Six Electron Domains
  • Leads to sp3d2 hybridization.
  • Results in an octahedral configuration.