Effective nuclear charge and shielding
Periodic Classification and Periodicity · Chemistry
Study notes
Estimate Z_eff for a 3s electron in Mg (Z=12, config 1s²2s²2p⁶3s²). Step 1: Slater: same-shell (3s,3p) electrons contribute 0.35 each: 1 × 0.35 = 0.35. Step 2: n-1 shell (n=2, 8 electrons): 8 × 0.85 = 6.80. Step 3: n-2 shell (1s, 2 electrons): 2 × 1.0 = 2.00. Step 4: σ = 0.35 + 6.80 + 2.00 = 9.15; Z_eff = 12 - 9.15 = 2.85.