Question
Wed July 18, 2012 By: Sivendu Sivendu

could you plz explain dipole moment in detail?

Expert Reply
Thu July 19, 2012

Dipole moment (µ) is the measure of net molecular polarity, which is the magnitude of the charge Q at either end of the molecular dipole times the distance r between the charges.

µ= Q X r

Dipole moments tell us about the charge separation in a molecule. The larger the difference in electronegativities of bonded atoms, the larger the dipole moment. For example, NaCl has the highest dipole moment because it has an ionic bond (i.e. highest charge separation).

For example, in CH3Cl molecule, chlorine is more electronegative than carbon, thus attracting the electrons in the C—Cl bond toward itself (Figure 1). As a result, chlorine is slightly negative and carbon is slightly positive in C—Cl bond. Since one end of C-Cl is positive and the other end is negative, it is described as a polar bond. To indicate the increased in electron density, the dipole is represented by an arrow with a cross at one end. The cross end of the arrow represents the positive end and the point of the arrow represents the negative end of the dipole.

The vector will point from plus to minus charge and run parallel with the bond between 2 atoms. The symbol ? indicates the partial charge of an individual atom.
Ask the Expert