“ionic radius”的概念、定义、翻译、参考文献-科学参考

ionic radius

Physics

A value assigned to the radius of an ion in a crystalline solid, based on the assumption that the ions are spherical with a definite size. X-ray diffraction can be used to measure the internuclear distance in crystalline solids. For example, in NaF the Na—F distance is 23.1 nm, and this is assumed to be the sum of the Na⁺ and F⁻ radii. By making certain assumptions about the shielding effect that the inner electrons have on the outer electrons, it is possible to assign individual values to the ionic radii—Na⁺ 9.6 nm; F⁻ 13.5 nm. In general, negative ions have larger ionic radii than positive ions. The larger the negative charge, the larger the ion; the larger the positive charge, the smaller the ion. The idea that an ion has a definite fixed size is only approximate, since its size depends on its environment to a certain extent.

Chemistry

A value assigned to the radius of an ion in a crystalline solid, based on the assumption that the ions are spherical with a definite size. X-ray diffraction can be used to measure the internuclear distance in crystalline solids. For example, in NaF the Na – F distance is 0.231 nm, and this is assumed to be the sum of the Na⁺ and F⁻ radii. By making certain assumptions about the shielding effect that the inner electrons have on the outer electrons, it is possible to assign individual values to the ionic radii – Na⁺ 0.096 nm; F⁻ 0.135 nm. In general, negative ions have larger ionic radii than positive ions. The larger the negative charge, the larger the ion; the larger the positive charge, the smaller the ion. See also hydrodynamic radius.

Geology and Earth Sciences

The distance between the nucleus of an ion and the electron in its outermost shell, usually reported in ångstroms or picometres (pm). Although no precise measurement can be made of the size of individual ions, in practice various techniques (e.g. X-ray diffraction) can be used to estimate ionic radii in particular crystal structures. Generally, it is found that: (a) within the same group of the periodic table ionic radius increases with increasing atomic number; (b) for elements of the same period (i.e. same horizontal row) that form positive ions, ionic radius decreases with increasing positive charge (reflecting the greater nuclear attraction on the same number of extranuclear electrons), for example, Na⁺ = 1.02Å, Mg²⁺ = 0.72Å, Al³⁺ = 0.53Å, Si⁴⁺ = 0.40Å; (c) for the same reasons, if an element can exist in different valence states, the higher the positive charge the smaller the ion, for example, Mn²⁺ = 0.82Å, Mn³⁺ = 0.65Å; (d) for elements of the same period forming negative ions, the ionic radius increases with increasing negative charge (due to electronic repulsion).

单词	ionic radius
释义	ionic radius Physics A value assigned to the radius of an ion in a crystalline solid, based on the assumption that the ions are spherical with a definite size. X-ray diffraction can be used to measure the internuclear distance in crystalline solids. For example, in NaF the Na—F distance is 23.1 nm, and this is assumed to be the sum of the Na⁺ and F⁻ radii. By making certain assumptions about the shielding effect that the inner electrons have on the outer electrons, it is possible to assign individual values to the ionic radii—Na⁺ 9.6 nm; F⁻ 13.5 nm. In general, negative ions have larger ionic radii than positive ions. The larger the negative charge, the larger the ion; the larger the positive charge, the smaller the ion. The idea that an ion has a definite fixed size is only approximate, since its size depends on its environment to a certain extent. Chemistry A value assigned to the radius of an ion in a crystalline solid, based on the assumption that the ions are spherical with a definite size. X-ray diffraction can be used to measure the internuclear distance in crystalline solids. For example, in NaF the Na – F distance is 0.231 nm, and this is assumed to be the sum of the Na⁺ and F⁻ radii. By making certain assumptions about the shielding effect that the inner electrons have on the outer electrons, it is possible to assign individual values to the ionic radii – Na⁺ 0.096 nm; F⁻ 0.135 nm. In general, negative ions have larger ionic radii than positive ions. The larger the negative charge, the larger the ion; the larger the positive charge, the smaller the ion. See also hydrodynamic radius. Geology and Earth Sciences The distance between the nucleus of an ion and the electron in its outermost shell, usually reported in ångstroms or picometres (pm). Although no precise measurement can be made of the size of individual ions, in practice various techniques (e.g. X-ray diffraction) can be used to estimate ionic radii in particular crystal structures. Generally, it is found that: (a) within the same group of the periodic table ionic radius increases with increasing atomic number; (b) for elements of the same period (i.e. same horizontal row) that form positive ions, ionic radius decreases with increasing positive charge (reflecting the greater nuclear attraction on the same number of extranuclear electrons), for example, Na⁺ = 1.02Å, Mg²⁺ = 0.72Å, Al³⁺ = 0.53Å, Si⁴⁺ = 0.40Å; (c) for the same reasons, if an element can exist in different valence states, the higher the positive charge the smaller the ion, for example, Mn²⁺ = 0.82Å, Mn³⁺ = 0.65Å; (d) for elements of the same period forming negative ions, the ionic radius increases with increasing negative charge (due to electronic repulsion).
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