Ranking Dipole Strength

There are 4 important trends to consider to rank the strength of a dipole

1. The relative strength of attractive force of a dipole is directly related to the strength of the charges formed on the molecules.

   Full charges > Permanent Partial Charges > Momentary Partial Charges

   • Can use Coulombs Law

     

2. The bigger the difference in electronegativity across a bond, the stronger the partial charges.

3. The strength of dipole attraction increases with the size of the molecule.

   Bigger molecule = more e- = greater random uneven distribution

4. Branching decreases dipole force.

   Charges become shielded by the structure (steric hindrance), when they are blocked by branching or are imbedded in the back bone of the structure