Frequently Asked Question

The effective nuclear charge (Zeff) for a valence electron in Co2+ can be calculated using Slater's rules. Here's how:
1. Electron Configuration: Co (atomic number 27) has the electron configuration [Ar] 3d7 4s2. In Co2+, two electrons are removed, leaving the configuration [Ar] 3d7.
2. Slater's Rules:
- Electrons in the same group (n) as the valence electron contribute 0.35 each (except for the 1s electron, which contributes 0.30).
- Electrons in the n-1 shell contribute 0.85 each.
- Electrons in the n-2 or lower shells contribute 1.00 each.
3. Calculation:
- For the 3d valence electrons in Co2+, the contribution from other 3d electrons is 6 x 0.35 = 2.10.
- The contribution from the 2s and 2p electrons (n-1 shell) is 8 x 0.85 = 6.80.
- The contribution from the 1s electrons (n-2 shell) is 2 x 1.00 = 2.00.
- The total shielding constant (S) is 2.10 + 6.80 + 2.00 = 10.90.
- Zeff = Z - S = 27 - 10.90 = 16.10
Therefore, the effective nuclear charge for a valence electron in Co2+ is approximately 16.10.