Hybridization and Valence Bond Theory

Introduction

• Instructor: Chad from Chad's Prep
• Objective: To explain the concept of hybridization in chemistry and valence bond theory.
• Purpose: Provide stress-free learning for various science preps including MCAT, DAT, and OAT.

Valence Bond Theory

• Core Idea: Atomic orbitals overlap during bond creation.
• Unpaired Electrons: Atoms use them to form bonds.
  • Example: H2 molecule
    • Hydrogen: 1s1 orbital overlaps to form the bond.
  • Example: HF molecule
    • Hydrogen: 1s1 orbital, Fluorine: 2p5 orbital
    • Overlap of Hydrogen's 1s orbital and Fluorine's 2p orbital.
  • Example: F2 molecule
    • Both Fluorine atoms: 2p orbitals overlap.
• Conclusion: Overlapping atomic orbitals share electrons to create bonds.
• Future Topic: Molecular Orbital Theory (introduced later).

Introduction to Hybridization

• Limitation in Valence Bond Theory: Atomic orbitals (s and p) are insufficient to explain bond angles in molecules like methane (CH4).
• Hybrid Orbitals: Combination of atomic orbitals (s, p, and sometimes d) to explain bond angles.
• Example: Methane (CH4)
  • Carbon: 1s2, 2s2, 2p2 (originally).
  • Promotion: Electron promoted to a higher energy orbital.
  • Formation: Carbon has four unpaired electrons ready to form four bonds.
• Problem with p orbitals: Original p orbitals arranged 90 degrees apart are insufficient to explain 109.5-degree bond angles.
• Solution: Hybridization (mixing and combining orbitals).
  • sp3 Hybridization: Combination of one s and three p orbitals to form four sp3 hybrid orbitals.
  • Result: Bond angles are adjusted to 109.5 degrees, fitting tetrahedral geometry.

Different Types of Hybridization

• Based on Electron Domains: Key to Identifying Hybridization
  • Four domains: sp3 hybridization
  • Three domains: sp2 hybridization
  • Two domains: sp hybridization
  • Five domains: sp3d hybridization (expanded octet)
  • Six domains: sp3d2 hybridization (expanded octet)

Detailed Examples

• sp2 Hybridization:
  • Example: Formaldehyde (CH2O)
  • Carbon: Three electron domains, trigonal planar geometry.
  • Hybrid Orbitals: Three sp2, one unhybridized p orbital.
  • Bond Angles: 120 degrees.
• sp Hybridization:
  • Example: Carbon Monoxide (CO)
  • Carbon: Two electron domains, linear geometry.
  • Hybrid Orbitals: Two sp, two unhybridized p orbitals.

Expanded Octets

• Explanation: Use of d orbitals for atoms with more than four electron domains.
• Hybridization: Five and Six Domains
  • Five domains: sp3d
  • Six domains: sp3d2
• Note: Some courses might not cover expanded octets.

Final Remarks

• Understanding Hybridization: Use electron domains to identify hybridization.
• Practice Resources: General Chemistry Master Course by Chad's Prep.
• Call to Action: Subscribe for more lessons, consider practice problems for mastering topics.

Additional Resources

• Chad's Prep Website: Various science preparatory courses.
• Study Guide: Diagrams and further reading on hybridization and valence bond theory.

Next Lesson Preview: Multiple bonds and sigma/pi bonds analysis.