![]() The SI unit for dipole moment is the coulomb-meter ( ) however, it is most commonly measured in debyes ( ). To calculate the dipole moment of a chemical bond, the following formula is used: (where is the bond dipole moment, is the magnitude of the separated charge, and is the distance of separation between the charges). In addition, the net dipole moment is affected by the geometry of the molecule, which can be predicted using VSEPR theory. Therefore, in polyatomic molecules (i.e., molecules made up of three or more atoms), the net dipole moment is the vector sum of all bond dipole moments present in the molecule. On the other hand, the molecular dipole moment (also referred to as the net dipole moment) is a measure of the polarity of the molecule as a whole. A bond dipole moment is a measure of the polarity of a chemical bond between two atoms in a molecule. It is important to note the distinction between bond dipole moments and molecular dipole moments. The arrow represents the shift of electron density in the molecule it points away from the less electronegative (and more positively-charged) hydrogen atom and towards the more electronegative (and more negatively-charged) fluorine atom. Shown below is an illustration of the dipole moment present in a molecule of hydrofluoric acid. Since they have both a magnitude and direction, dipole moments are considered to be a vector quantity. Greater differences in electronegativity will consequently lead to larger dipole moments. A dipole moment is a result of unequal electron distribution, which occurs due to differences in electronegativity between chemically-bonded atoms (since electrons tend to move towards more electronegative atoms). Topics Covered in Other ArticlesÄipole moments occur in any system in which there is a separation of positive and negative electrical charges therefore, they can be found in both ionic and covalent bonds. Lastly, we provide several examples that demonstrate the importance of molecular geometry in determining net dipole moments. Then, we discuss the formula used to calculate dipole moments and explain their classification as a vector (rather than scalar) quantity. First, we begin with a basic introduction to the presence of dipole moments in chemical bonds and molecules. In this tutorial, you will learn all about dipole moments.
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