Definition

1. Noun:
   • A measure of the separation of positive and negative electrical charges in a system: A dipole moment quantifies the polarity of a molecule or a pair of charges. It is a vector quantity, possessing both magnitude and direction, pointing from the negative charge towards the positive charge.
   • The product of the charge magnitude and the distance separating the charges: For a simple system of two equal and opposite charges, the dipole moment (μ) is calculated as the charge (q) multiplied by the displacement vector (d) separating them (μ = q * d).

Usage Examples

• Noun:
  • Water has a large dipole moment because of its bent molecular shape and the difference in electronegativity between oxygen and hydrogen.
  • The dipole moment of the molecule determines how it interacts with an external electric field.
  • Scientists measured the dipole moment to confirm the polarity of the new compound.

Advanced Usage

• "To have a dipole moment": Describes a molecule or system that is polar.
  • Carbon dioxide is linear and symmetrical, so it does not have a dipole moment.
• "Net dipole moment": The overall dipole moment of a molecule resulting from the vector sum of individual bond dipole moments.
  • Although each C-Cl bond is polar, carbon tetrachloride has no net dipole moment due to its tetrahedral symmetry.

Variants and Related Words

• Dipole (n): A pair of equal and opposite electric charges or magnetic poles separated by a small distance.
  • A permanent magnet is a magnetic dipole.
• Bond dipole moment (n): The dipole moment of a single chemical bond, due to a difference in electronegativity between the bonded atoms.
  • The bond dipole moment in a hydrogen-chlorine bond is significant.
• Electric dipole moment (n): A specific type of dipole moment related to electric charge distribution.

Synonyms

• Polar moment (in specific contexts, though less common).
• Electric moment (in a general sense).

Related Phrases

• Dipole moment vector: Emphasizes the directional nature of the quantity.
  • The dipole moment vector points towards the more electronegative atom.
• To calculate/measure the dipole moment: Common collocations describing actions performed on this property.
  • We can calculate the dipole moment from the molecular geometry and bond polarities.

Noun

1. the moment of a dipole