Dipole
Definition
A separation of electric charge: one end of a bond or molecule slightly positive, the other slightly negative.
Symbol: · Unit: debye (D)
Technical definition
A dipole is a separation of positive and negative charge characterized by a dipole moment, the product of charge magnitude and separation distance. Bond dipoles arise from polar bonds, and the molecular dipole depends on both bond polarity and geometry.
Example
Water has a molecular dipole moment of 1.85 D, with the oxygen end negative and the hydrogen end positive, which is why water dissolves salts so well.
Common confusion
Bond dipoles and molecular dipoles are not the same. Vector addition of bond dipoles determines the molecular dipole, and symmetrical molecules like CO2 have zero net dipole despite polar bonds.