Question

Account for the relative magnitudes of the Slater parameters (e.g. why is σ 0.35, 0.85, or 1.00 for e- in the n, n-1, and n-2 orbitals?)

Answer 1

The electrons which are closer to the nucleus can shied the valence electron better than the electrons which are farther from the nucleus because of the greater electrostatic attraction they exert on the nucleus.(electrostatic attraction increase with decrease in distance- Coulomb’s law)

Thus the shielding constants should increase with decrease in the distance between the nucleus and the shielding electrons

The distance of the orbitals from the nucleus is in the order

n   , n-1 , n-2   Highest to lowest

So the shielding constants are in the order lowest to highest (0.35, 0.85, 1.00)