Rules
Firstly, the electrons are arranged in to a sequence of groups in order of increasing principal quantum number n, and for equal n in order of increasing azimuthal quantum number l, except that s- and p- orbitals are kept together.
- 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 type, an amount of 0.85 from each electron with principal quantum number (n) one less and an amount of 1.00 for each electron with an even smaller principal quantum number
- If the group is of the or, type, an amount of 1.00 for each electron inside it. This includes i) electrons with a smaller principal quantum number and ii) electrons with an equal principal quantum number and a smaller azimuthal quantum number (l)
In tabular form, the rules are summarized as:
| Group | Other electrons in the same group | Electrons in group(s) with principal quantum number n and azimuthal quantum number < l | Electrons in group(s) with principal quantum number n-1 | Electrons in all group(s) with principal quantum number < n-1 |
|---|---|---|---|---|
| 0.30 | N/A | N/A | N/A | |
| 0.35 | N/A | 0.85 | 1 | |
| or | 0.35 | 1 | 1 | 1 |
Read more about this topic: Slater's Rules
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