Chemistry: Hybridization and Bonding Concepts

Hybridization of Orbitals and Bonding

• Bond angles of 109.5º do not align with traditional orbital theories; hybridization explains this discrepancy.

Types of Bonds

• Sigma (σ) Bonds:

  • Form through end-to-end orbital overlap.
  • Present in all types of bonds.

• Pi (π) Bonds:

  • Form from side-to-side overlap of unhybridized p-orbitals.
  • There is no overlap in pi bonds.
  • In a double bond, there is one pi bond; in a triple bond, there are two pi bonds.

Bond Structure

• Single Bonds: Consist solely of sigma (σ) bonds.
• Double Bonds: Comprised of one sigma bond and one pi bond.
• Triple Bonds: Comprised of one sigma bond and two pi bonds.

Hybridization Concept

• Hybridization modifies molecular models to represent observed molecular structures accurately.
• It involves mixing native atomic orbitals to create hybrid orbitals designed for bonding.
• Hybrid orbitals arrange themselves to maximize distance from one another.

Types of Hybridization

• sp³: Involves four effective pairs; bond angles of 109.5° (tetrahedral), 107.3° (pyramidal), or 104.5° (bent).
• sp²: Involves three effective pairs with a bond angle of 120° (trigonal planar).
• sp: Involves two effective pairs (linear geometry).
• dsp³: Involves five effective pairs (trigonal bipyramidal geometry).
• d²sp³: Involves six effective pairs (octahedral geometry).

sp³ Hybridization

• Characterizes molecules such as CH₄, NH₃, H₂O, SO₄²⁻, and ClO₃⁻.
• The hybridized sp³ orbitals overlap with hydrogen 1s orbitals in methane (CH₄) to form four sigma bonds.

sp² Hybridization

• Presents a trigonal planar configuration with bond angles of 120°.
• Characterizes molecules like SO₃, C₂H₄, and CO₃²⁻.
• In ethylene (C₂H₄), it features five sigma bonds and one pi bond, formed through the overlap of hybridized and unhybridized orbitals.

Bonding Mechanism

• Hybridized orbitals are responsible for sigma bonds.
• Unhybridized orbitals contribute to pi bonds.