A Simple Note on Dipole Moment

The dipole moment is created when atoms in a molecule share electrons unequally. This happens when the one atom is more electronegative than another, causing that atom to pull harder on the shared pair of electrons. A polar bond is a covalent bond established mutually between two atoms with unequally distributed electrons. As a result, the molecule develops a tiny electrical dipole moment, with one end slightly positive and the other slightly negative. Electric dipoles have a charge that is less than a full unit charge, and are symbolized by delta plus (+) and delta negative (-). Because polar covalent links segregate positive and negative charges, molecules with polar covalent bonds interact with dipoles in other compounds. This dipole-dipole interaction causes intermolecular forces to form between the molecules.

The electric dipole is formed when the two electrical charges of opposing sign and equal magnitude are separated by a distance. The dipole moment (μ) is used to find the size of a dipole.

Dipole Moment Characteristics 

1. Dipole moment is a vector quantity.
2. Non-polar molecules have no dipole moment.
3. The molecular dipole moment is equal to 0 for symmetrically applied molecular dipole moments.

For example, because carbon dioxide is linear, the net bond moment is 0 because the individual bond moments cancel out.

For example, carbon tetrachloride, for example, has zero dipole moment due to its highly symmetrical tetrahydro structure.

4. The percentage ionic nature of a covalent bond is calculated using the dipole moment.

Bond Dipole Moment

In polyatomic molecules, the bond dipole moment differs from the total dipole moment.

Bond dipole moment is the dipole moment between a diatomic molecule’s single bond, whereas total dipole moment is the vector sum of all bond dipoles in a polyatomic molecule

Thus, differences in the sizes of the two atoms, hybridization of the orbitals, and the direction of lone pair electrons all affect the total molecule dipole moment.

The Product of Charge And Distance Of Charge

When two electrical charges of identical magnitude but opposite signs are separated by a distance, the dipole moment is formed. The dipole moment (μ) is also used to calculate the dipole’s size. The dipole moment, which is equal to the distance between the charge X, is measured in Debye units, with 1 Debye equaling 3.34*10^-30cm. 

The product of the molecule’s electric charge magnitude and the internuclear distance between its atoms can be used to define the dipole moment. It is calculated by using the following standard formula:

Dipole Moment (µ) = Charge (Q) × Distance of Separation (d)

(µ) = (Q) × (d)

Where, Q is the magnitude of the partial charges 𝛿+ and 𝛿–, and d is the distance between 𝛿+ and 𝛿–, and is the bond dipole moment.

Unit of Dipole Moment

It’s measured in Debye units, which are denoted by the letter D.

D = 3.33564 ×10-30 Cm;

C = Coulomb,

m = meter.

Another main Equation that is provided below can be used to compute a molecule’s dipole moment:

μ =∑q_ir_i

Where,

μ = the vector of the dipole moment

The size of the i^th charge is given by qi, and

The vector R_i denotes the position of the i^th charge.

Uses Of Dipole Moment

• In order to determine the structure (shape) of the molecules, follow these steps: Molecules having specified dipole moment values will be bent or angular in shape, and their structures will not be symmetrical. Molecules having zero dipole moment, on the other hand, will have an asymmetrical form.
• When looking for symmetry in molecules, keep in mind that molecules with two or more polar connections will not be symmetrical and will have some dipole moment. H2O is 1.84 D, and CH3Cl (methyl chloride) is 1.86 D. Such molecules will have symmetrical configurations if similar atoms in the molecule are connected to the central atom with the resultant dipole moment zero. CO2, CH4 are two examples.
• When distinguishing between cis- and trans-isomers, keep the following in mind: Isomer with a larger dipole moment is trans-isomer, while isomer with a lower dipole moment is cis-isomer.
• When distinguishing between ortho, meta, and para-isomers, the dipole moment of the para-isomer will be zero, whereas the dipole moment of the ortho-isomers will be greater than that of the meta-isomer.

Conclusion

A dipole moment is a measurement of the distance between two electrical charges that are opposite each other. The fact that the water molecule is polar (has a dipole moment) affects its properties significantly. Water molecules can surround and attract both positive and negative ions due to their polarity. Ionic materials can dissolve in water because of these attractions. The charge separation in a molecule is done by dipole moments. The dipole moment is known to be proportional to the differences in electronegativities of linked atoms. Because it possesses an ionic bond.