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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Dipole moment

A measure of charge separation, μ=Q×r\mu = Q \times r (charge times distance), usually given in debye (1 D ≈ 3.34⋅10−30 C m\pu{3.34e-30 C m}). A molecule's dipole moment is the vector sum of its bond dipoles, so it depends on both bond polarity and shape.

Central O atom bonded to 2 H atoms, with 2 lone pairs.HOH109.5°Ideal bond angle: 109.5°
In HX2O\ce{H2O} the two O–H bond dipoles add along the bisector of the H–O–H angle.

Example

HX2O\ce{H2O} has μ≈1.85\mu \approx 1.85 D and NHX3\ce{NH3} about 1.47 D, while COX2\ce{CO2} and CClX4\ce{CCl4} have μ=0\mu = 0.