Between $ ext{Na}^+$ and $ ext{Ag}^+$, which is a stronger Lewis acid and why?

Question

Between $	ext{Na}^+$ and $	ext{Ag}^+$, which is a stronger Lewis acid and why?

Professor PC Thomas Classes · Answer

A Lewis acid is an electron pair acceptor. The strength of a Lewis acid depends on its ability to attract electrons.
$	ext{Ag}^+$ is a stronger Lewis acid than $	ext{Na}^+$. This is because $	ext{Ag}^+$ has a pseudo-noble gas configuration ($4d^{10}$) and a higher effective nuclear charge compared to $	ext{Na}^+$ which has a noble gas configuration ($2s^2 2p^6$). The poor shielding of $d$-electrons in $	ext{Ag}^+$ leads to a higher effective nuclear charge, making it more capable of accepting an electron pair. Additionally, $	ext{Ag}^+$ can easily accommodate electron pairs in its vacant $5s$ and $5p$ orbitals to form complexes.