Frequently Asked Question

Slater's rules are a set of empirical rules used to estimate the effective nuclear charge (Zeff) experienced by an electron in a polyelectronic atom. Here's a concise list of the key rules:
1. Electron Shielding: Electrons in inner shells shield outer electrons from the full nuclear charge. Electrons in the same shell provide some shielding. Shielding constants are assigned to each group of electrons based on their principal quantum number (n) and their orbital type (s, p, d, f).
2. Shielding Constants:

(n-1) and lower shells: Electrons in these shells contribute 1.00 to the shielding constant.

Electrons in the same shell: Electrons in s and p orbitals contribute 0.35 to the shielding constant. Electrons in d and f orbitals contribute 0.35 to the shielding constant.

Electrons in the same shell but higher in energy: Electrons in higher-energy orbitals contribute 0.85 to the shielding constant.
3. Effective Nuclear Charge: The effective nuclear charge is calculated as Zeff = Z - S, where Z is the atomic number and S is the shielding constant.
4. Example: For oxygen (O, atomic number 8), the electronic configuration is 1s²2s²2p⁴.

The 1s electrons shield the 2s and 2p electrons with a shielding constant of 2.00 (1.00 each from the 1s electrons).

The 2s electrons shield each other with a shielding constant of 0.35.

The 2p electrons shield each other with a shielding constant of 0.35.

The total shielding constant (S) for oxygen is 2.00 + 0.35 + 0.35 = 2.70.

The effective nuclear charge (Zeff) for the 2s and 2p electrons in oxygen is 8 - 2.70 = 5.30.
Slater's rules provide a good approximation for Zeff, which is important for understanding the behavior and properties of atoms and molecules.