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In quantum chemistry, Slater's rules provide numerical values for the effective nuclear charge concept. In a many-electron atom, each electron is said to experience less than the actual nuclear charge owing to shielding or screening by the other electrons. For each electron in an atom, Slater's rules provide a value for the screening constant, denoted by ''s'', ''S'', or ''σ'', which relates the effective and actual nuclear charges as : The rules were devised semi-empirically by John C. Slater and published in 1930. Revised values of screening constants based on computations of atomic structure by the Hartree–Fock method were obtained by Enrico Clementi ''et al'' in the 1960s. ==Rules== Firstly,〔 the electrons are arranged into a sequence of groups in order of increasing principal quantum number n, and for equal n in order of increasing ) () () () () () () (5p ) () etc. Each group is given a different shielding constant which depends upon the number and types of electrons in those groups preceding it. The shielding constant for each group is formed as the ''sum'' of the following contributions: #An amount of 0.35 from each ''other'' electron within the ''same'' group except for the () group, where the other electron contributes only 0.30. #If the group is of " TITLE="azimuthal quantum number l, except that s- and p- orbitals are kept together. :() () () () () () () (5p ) () etc. Each group is given a different shielding constant which depends upon the number and types of electrons in those groups preceding it. The shielding constant for each group is formed as the ''sum'' of the following contributions: #An amount of 0.35 from each ''other'' electron within the ''same'' group except for the () group, where the other electron contributes only 0.30. #If the group is of ">azimuthal quantum number l, except that s- and p- orbitals are kept together. :() () () () () () () (5p ) () etc. Each group is given a different shielding constant which depends upon the number and types of electrons in those groups preceding it. The shielding constant for each group is formed as the ''sum'' of the following contributions: #An amount of 0.35 from each ''other'' electron within the ''same'' group except for the () group, where the other electron contributes only 0.30. #If the group is of the (p ) type, an amount of 0.85 from each electron with principal quantum number ''n'' one less than that of the group, and an amount of 1.00 for each electron with principal quantum number two or more less. #If the group is of the () or (), type, an amount of 1.00 for each electron "closer" to the atom than the group. This includes i) electrons with a smaller principal quantum number ''n'' and ii) electrons with an equal principal quantum number and a smaller azimuthal quantum number ''l''. In tabular form, the rules are summarized as: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Slater's rules」の詳細全文を読む スポンサード リンク
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