Question

Rank the $5s,5p,5d,5f$ and $5g$ orbitals in order of increasing shielding ability:

• A. $5g<5f<5d<5s<5p$
• B. $5g<5f<5p<5d<5s$
• C. $5g<5d<5f<5p<5s$
• D. None of these

Answer 1

The correct option is D None of these

Penetration describes the proximity of electrons in an orbital to the nucleus. Electrons which experience greater penetration experience less shielding and therefore experience a larger Effective Nuclear Charge $\left(Z_{eff}\right)$, but shield other electrons more effectively.

Therefore, for the same shell value (n) the penetrating power of an electron follows this trend in subshells:

$s>p>d>f$

Because the order of electron penetration from greatest to least is s, p, d, f; the order of the amount of shielding done is also in the order s, p, d, f.

Since the 2s electron has more density near the nucleus of an atom than a 2p electron, it is said to shield the 2p electron from the full effective charge of the nucleus. Therefore the 2p electron feels a lesser effect of the positively charged nucleus of the atom due to the shielding ability of the electrons closer to the nucleus than itself, (i.e. 2s electron).