Lanthanide contraction (Poor 4f shielding → Z_eff rises → smaller ionic radii from Ce to Lu)
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Poor 4f shielding → Z_eff rises → smaller ionic radii from Ce to Lu
What each symbol means
| Symbol | What it stands for |
|---|---|
| Z_{\mathrm{eff}} | Effective nuclear charge felt by valence 6s/5d electrons |
When to use this
Atomic/ionic radii decrease ~15–20 pm across Ln series; 4f poorly shields nuclear charge.