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The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system: that is, a measure of the system's overall polarity. The SI unit for electric dipole moment is the coulomb-metre (C⋅m). The debye (D) is another unit of measurement used in atomic physics and chemistry.
The electron's electric dipole moment (EDM) must be collinear with the direction of the electron's magnetic moment (spin). [1] Within the Standard Model, such a dipole is predicted to be non-zero but very small, at most 10 −38 e⋅cm, [2] where e stands for the elementary charge.
The polarizability of an atom or molecule is defined as the ratio of its induced dipole moment to the local electric field; in a crystalline solid, one considers the dipole moment per unit cell. [1] Note that the local electric field seen by a molecule is generally different from the macroscopic electric field that would be measured externally.
The dipole moment per unit volume is defined as the dielectric polarization. If this dipole moment changes with the effect of applied temperature changes, applied electric field, or applied pressure, the material is pyroelectric, ferroelectric, or piezoelectric, respectively. The ferroelectric effect is exhibited by materials which possess an ...
The size of the induced dipole moment is equal to the product of the strength of the external field and the dipole polarizability of ρ. Dipole moment values can be obtained from measurement of the dielectric constant. Some typical gas phase values given with the unit debye are: [7] carbon dioxide: 0; carbon monoxide: 0.112 D; ozone: 0.53 D
Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Molecules with symmetry point groups or containing inversion symmetry will not have a permanent dipole moment, while highly ionic molecular species have a very large dipole moment, e.g. gas-phase potassium bromide, KBr, with a dipole moment of 10.41 D. [3] A proton and an electron 1 Å apart have a dipole ...
Note that the dipole moments drawn in this diagram represent the shift of the valence electrons as the origin of the charge, which is opposite the direction of the actual electric dipole moment. The bond dipole moment [5] uses the idea of electric dipole moment to measure the polarity of a chemical bond within a molecule. It occurs whenever ...
[3] [7] It can also be prepared by heating cobalt metal to above 250 °C in a stream of carbon monoxide gas at about 200 to 300 atm: [3] 2 Co + 8 CO → Co 2 (CO) 8. It exist as a mixture of rapidly interconverting isomers. [2] [3] In solution, there are two isomers known that rapidly interconvert: [5]