Hybridization of Atomic Orbitals

Introduction to Hybridization

• Hybridization: Process of combining atomic orbitals to create hybrid orbitals.
• Examples:
  • sp3 hybrid orbital: Combination of 1 s orbital and 3 p orbitals.
  • sp2 hybrid orbital: Combination of 1 s orbital and 2 p orbitals.
  • sp hybrid orbital: Combination of 1 s orbital and 1 p orbital.
  • d2sp3 hybridization: Involves 2 d orbitals, 1 s orbital, and 3 p orbitals.

Characteristics of Orbitals

• s orbital: Spherical shape; indicates the probability location of an electron.
• p orbitals: Three types based on orientation:
  • px: Along x-axis
  • py: Along y-axis
  • pz: Along z-axis
• Heisenberg's Uncertainty Principle: Impossible to know the exact position of an electron.

Hybridization in Carbon

• Electron Configuration: 1s² 2s² 2p²
• Valence Electrons: Carbon has 4 valence electrons.
• sp3 Hybridization:
  • Mixes 1 s orbital and 3 p orbitals.
  • 25% s character and 75% p character.
  • Energy level closer to 2p than 2s.
  • Results in 4 degenerate orbitals (same energy).
  • Electrons added one at a time with parallel spins.

sp2 Hybridization

• Uses 1 s orbital and 2 p orbitals.
• Remaining one p orbital is unhybridized.
• s and p character: 33% s and 67% p.
• Energy level is closer to 2p than 2s but less than sp3.
• Results in 3 hybrid orbitals.

sp Hybridization

• Uses 1 s orbital and 1 p orbital; other two p orbitals remain unhybridized.
• s and p character: 50% s and 50% p.
• Energy level is between s and p orbitals.
• Results in 2 hybrid orbitals.

Sigma (σ) and Pi (π) Bonds

• Sigma Bonds:
  • Formed from the overlap of atomic/hybrid orbitals.
  • Stronger than pi bonds.
  • Present in every single bond.
• Pi Bonds:
  • Formed from unhybridized p orbitals.
  • Present in double and triple bonds.
• Bond Strength:
  • Triple bonds are stronger than single bonds due to the presence of two π bonds.
  • Triple bonds are shorter than single bonds.
  • Sigma bonds are stronger than pi bonds.

Example Structure Analysis

• Counting sigma and pi bonds:
  • Every bond contains 1 sigma bond.
  • Every double bond contains 1 pi bond.
  • Example: In a structure with 7 bonds and 2 double bonds:
    • Sigma bonds: 7
    • Pi bonds: 2