shielding effect

Question

Which subshell provides poorest shielding?

RankGuru · Accepted Answer

1. **Shielding (Screening)**: The decrease in nuclear pull felt by valence electrons due to the presence of intervening inner electrons.
2. **Effectiveness Order**: This depends on the spatial distribution (penetration) of orbitals: **$s > p > d > f$**.
3. **Why and how?**: 
   - **$s$ orbitals** have a spherical shape and get very close to the nucleus, providing excellent protection.
   - **$d$ and $f$ orbitals** are 'diffuse' and geometrically less effective at 'covering' the nuclear charge.
4. **Consequence**: Poor shielding by $f$-electrons is the fundamental cause of Lanthanide Contraction.

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shielding effect

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More shielding effect Practice Questions

The shielding effect on valence electrons is maximum when the inner shells contain: