Frequently Asked Question

The effective nuclear charge (Zeff) for a valence electron in cobalt (Co) can be calculated using Slater's rules. Here's how:
1. Electron Configuration: Cobalt has the electron configuration [Ar] 3d7 4s2. We are interested in the 4s valence electrons.
2. Slater's Rules: We need to determine the shielding constant (S) for the 4s electrons. According to Slater's rules:

Electrons in the same group (n) as the valence electron contribute 0.35 each (except for the 1s electrons, which contribute 0.30). In this case, the other 4s electron contributes 0.35.

Electrons in the next lower shell (n-1) contribute 0.85 each. The 3d electrons contribute 0.85 each, and there are 7 of them (0.85
7 = 5.95).

Electrons in lower shells (n-2 or lower) contribute 1.00 each. The core electrons (1s2, 2s2, 2p6) contribute 10.00 (1.00
10 = 10.00).
3. Calculate Shielding Constant (S): S = 0.35 + 5.95 + 10.00 = 16.30
4. Calculate Effective Nuclear Charge (Zeff): Zeff = Z - S, where Z is the atomic number of cobalt (27).

Zeff = 27 - 16.30 = 10.7
Therefore, the effective nuclear charge for a valence electron in cobalt is approximately 10.7.