Organic Chemistry Hybridization

Organic Chemistry Hybridization — What You Actually Need to Remember

1. Definition of an Orbital

  • Orbital: A region of space where an electron is most likely found; not a fixed path or orbit.

2. s Orbitals

  • Shape: Spherical.
  • Directionality: No inherent directionality.
  • Energy Level: Lower energy compared to p orbitals.
  • Quantity: One s orbital per energy level.

3. p Orbitals

  • Shape: Dumbbell-shaped.
  • Directionality: Directional; categorized as px, py, pz.
  • Energy Level: Higher energy than s orbitals.
  • Bonding Function: Used to form π (pi) bonds.

4. Definition of Hybridization

  • Hybridization: The process of mixing s and p orbitals to form new, equivalent orbitals which provide a better explanation of observed molecular shapes.

5. Essential Hybridization Table

  • Electron Groups and Hybridization:

    1. 2 Electron Groups:
    • Hybridization: sp
    • Molecular Shape: Linear
    • Bond Angles: 180°
    1. 3 Electron Groups:
    • Hybridization: sp²
    • Molecular Shape: Trigonal planar
    • Bond Angles: 120°
    1. 4 Electron Groups:
    • Hybridization: sp³
    • Molecular Shape: Tetrahedral
    • Bond Angles: 109.5°

  • Counting Electron Groups:

    • Single Bond: Counts as 1 group
    • Double Bond: Counts as 1 group
    • Triple Bond: Counts as 1 group
    • Lone Pair: Counts as 1 group

6. Sigma vs. Pi Bonds

  • σ (sigma) Bonds: Formed from hybrid orbitals through head-on overlap.
  • π (pi) Bonds: Formed from unhybridized p orbitals through side-by-side overlap.
  • Double Bonds: Comprise 1 σ bond + 1 π bond.
  • Triple Bonds: Comprise 1 σ bond + 2 π bonds.

7. Exam Method for Identifying Hybridization

  1. Draw the Lewis structure of the molecule.
  2. Select one atom of interest.
  3. Count the number of electron groups around the atom.
  4. Match the count to the appropriate hybridization type (sp / sp² / sp³).

Practice Problems

  1. Identify the hybridization of carbon in CO₂.
  2. Identify the hybridization of carbon in HCN.
  3. Identify the hybridization of each carbon in C₃H₈.
  4. Identify the hybridization of nitrogen in NH₃.
  5. Identify the hybridization of oxygen in H₂O.
  6. Identify the hybridization of each carbon in HC≡CH.
  7. Identify the hybridization of carbon and oxygen in CH₃OH.
  8. Identify the hybridization of the central atom in BF₃.

Answer Key for Practice Problems

  1. CO₂: sp
  2. HCN: sp
  3. C₃H₈: sp²
  4. NH₃: sp³
  5. H₂O: sp³
  6. HC≡CH: sp
  7. CH₃OH: C = sp³, O = sp³
  8. BF₃: sp²