HYDROGEN BONDING

• WHAT IS HYDROGEN BONDING?

  special case of permanent dipole-dipole attractions (H atom bonded to very electronegative atom)
• EXAMPLES OF MOLECULES WITH HYDROGEN BONDING?

  HF, H2O, NH3, alcohols, carboxylic acids, amines, amino acids
• WHAT CAUSES HYDROGEN BONDING?

  • polar bond between H and N/O/F
  • leaves H nucleus exposed (H only has one electron)
  • strong attraction from lone pair on N/O/F of one molecule to exposed H nucleus on another
• WHAT IS HYDROGEN BONDING NOT?

  a bond (it is a strong intermolecular force)
• WHAT SHOULD ALWAYS BE SHOWN WHEN DRAWING HYDROGEN BONDS?

  • all lone pairs
  • slightly positive/ negative charges
  • dotted line (between lone pair on one molecule and slightly positive H on another)
• IS THE HYDROGEN ION SLIGHTLY POSITIVE OR SLIGHTLY NEGATIVE IN HYDROGEN BONDING?

  slightly positive
• WHAT ARE THE THREE MOST ELECTRONEGATIVE ATOMS?

  N, O, F
• HOW TO REMEMBER THREE MOST ELECTRONEGATIVE ATOMS?

  Daddy NOF
• WHAT TYPE OF INTERMOLECULAR FORCE IS THE STRONGEST?

  hydrogen bonding (Daddy NOF)
• WHEN IS THE ONLY OCCASION HYDROGEN BONDING OCCURS?

  when directly bonded
• STRONGEST TO WEAKEST INTERMOLECULAR FORCES?

  hydrogen bonding > permanent dipole-dipole > van der Waals'