polarizabiliteetti

Polarizabiliteetti, often translated as polarizability, is a measure of how easily the electron cloud of an atom or molecule can be distorted by an external electric field. When an electric field is applied, the positive nuclei and the negative electron clouds within the atom or molecule shift slightly in opposite directions. This displacement creates an induced dipole moment, which is a separation of positive and negative charges. The polarizability quantifies the magnitude of this induced dipole moment in response to a given electric field strength.

A higher polarizability means that the electron cloud is more diffuse and less tightly bound to the atomic nuclei, making it easier to distort. Conversely, a lower polarizability indicates a more compact and tightly held electron cloud. Polarizability is a crucial property in understanding various chemical and physical phenomena, including intermolecular forces (like London dispersion forces), the refractive index of materials, and the dielectric properties of substances. It is typically represented by the Greek letter alpha (α). The SI unit for polarizability is C m²/V, although atomic units are also frequently used. Molecular polarizability can be anisotropic, meaning it depends on the direction of the applied electric field relative to the molecule's structure.