Valence Bond Theory and Hybridization

Key Concepts

• Valence Bond Theory: Used to predict bond angles and shapes of molecules.
• Hybridization: Process of mixing atomic orbitals to form new hybrid orbitals suitable for the pairing of electrons.
• VSEPR Theory: Often matches predictions made by Valence Bond Theory. Used to predict the shape of molecules.

Example of Molecule Analysis

Hydrogen Atoms

• Use s orbitals.
• Do not undergo hybridization due to lack of other available orbitals.

Carbon Atoms

• Carbon with 4 Electron Domains:
  • Hybridization: sp³
  • Predicted Bond Angle: ~109.5°
• Carbon with 3 Electron Domains:
  • Hybridization: sp²
  • Predicted Bond Angle: 120°

Oxygen Atoms

• Oxygen with 3 Electron Domains:
  • Hybridization: sp²
• Oxygen with 4 Electron Domains:
  • Hybridization: sp³

Molecules with Expanded Octet

Example with Sulfur

• Sulfur with 5 Electron Domains:
  • Hybridization: sp³d
  • Shape: Seesaw
  • Bond Angles:
    • Trigonal Planar Section: ~120°
    • Axial Positions: ~90° (less due to electron pair repulsion)

General Predictions

• Electron Pair Repulsion: Causes bond angles to be slightly less than ideal angles due to additional push from lone pairs.
• For atomic orbitals being hybridized, they are mixed to create new orbitals that define the geometry of molecules.