Skip to main content

Molecular Structure of Acids and Bases

The molecular structure of acids and bases determines their strength, reactivity, and behavior in aqueous solutions.

Acids​

Key Features​

  • Acids donate protons (H⁺)
  • Common structural traits:
    • Polar H–X bond (H bonded to a highly electronegative atom)
    • Examples: HCl, HNO₃, H₂SO₄
  • Oxoacids: Acids containing oxygen and hydrogen attached to another atom (like HNO₃)
  • Carboxylic acids: Contain –COOH group (e.g., CH₃COOH)

Factors Affecting Acid Strength​

  • Bond polarity: More polar H–X bonds → stronger acid
  • Bond strength: Weaker H–X bonds → easier proton release
  • Resonance: Conjugate base stability increases acid strength

Bases​

Key Features​

  • Bases accept protons or donate electron pairs
  • Structural traits:
    • Lone pair on N, O, or other electronegative atom (e.g., NH₃, H₂O, OH⁻)
  • Amine bases: Contain –NH₂ group

Factors Affecting Base Strength​

  • Availability of lone pair: More accessible lone pair → stronger base
  • Electronegativity: Highly electronegative atom holding lone pair tightly → weaker base
  • Resonance and inductive effects: Stabilize conjugate acids → stronger base

Importance​

  • Molecular structure explains why some acids/bases are strong or weak
  • Guides reaction prediction, buffer design, and titration calculations

Have Questions?​

If you have any questions, or are looking for more resources, you can join our Discord Server