Frequently Asked Question

The effective nuclear charge (Zeff) for a valence electron in Co2+ (atomic number 27) can be calculated using Slater's rules. Here's how:
1. Electron Configuration: Co2+ has the electron configuration [Ar] 3d7. The valence electron is in the 3d orbital.
2. Slater's Rules:

Electrons in the same group (n) contribute 0.35 each, except for the 1s electrons which contribute 0.30. (In this case, the other 6 3d electrons contribute 0.35 each)

Electrons in the (n-1) group contribute 0.85 each. (The 2s and 2p electrons contribute 0.85 each)

Electrons in lower groups (n-2, n-3, etc.) contribute 1.00 each. (The 1s electrons contribute 1.00 each)
3. Calculation:

Zeff = Z - S (where Z is the atomic number and S is the shielding constant)

S = (0.35
6) + (0.85
8) + (1.00
2) = 11.6

Zeff = 27 - 11.6 = 15.4
Therefore, the effective nuclear charge for a valence electron in Co2+ is approximately 15.4.