Effective Charge on Valence Electrons of Sb

[BugzBunny]

Homework Statement

Given Slater's expression for effective charge below, determine the effective charge experienced by the valence electrons of Sb.

Homework Equations

Z_eff = Z - 0.35a - 0.85b - c
Where
Z= the nuclear charge; a= the number of s and p electrons in the same shell; b= the number of s and p electrons in the shell one deeper; c= the remaining electrons

The Attempt at a Solution

I have grouped the electron configuration as such:
[1s²] [2s² 2p⁶] [3s² 3p⁶] [3d¹⁰] [4s² 4p⁶] [4d¹⁰] [5s² 5p³]

Z_eff = 51 - 0.35(4) - 0.85(18) - 28 = 6.3

Is this the correct interpretation? My course notes and the problem's formulation are ambiguous so that the 4d electrons could be construed as a factor of b (× 0.85) or of c (× 1).

Thank you for your help.

 

[DrDu]

https://en.wikipedia.org/wiki/Slater's_rules