Answer to Question #158302 in General Chemistry for Christian

Question

 What is the relationship between the dipole moment and bond moment? Explain it with  examples, how is it possible for a molecule to have bond moments and yet be nonpolar? 

Answer 1

The terms coupling moment and dipole moment are based on similar principles, but differ depending on the application. The coupling moment is also known as the dipole coupling moment. This is the polarity of a chemical bond that is located inside a particular molecule. The main difference between the bond moment and the dipole moment is that the bond moment occurs in a covalent chemical bond, whereas the dipole moment occurs between two ions in an ionic bond or between two atoms in a covalent bond.

In the HCl molecule, the electron density distribution along the H-Cl bond is such that the electric “center of gravity” of the negative charge is shifted to the Cl atom, and the “center of gravity” of the positive charge is shifted to the H atom. As a result, effective H $\delta$ ⁺ - Cl $\delta$^- charges arise on the chlorine and hydrogen atoms .

The polarity of the molecules is affected not only by the polarity of the bonds, but also by the geometry of the molecules, so if there is a polar bond in the molecule, it can be non-polar.

SO₂(O=S=O)