Question

The polarising action of $C{d}^{2+}$ on anions is stronger than that of $C{a}^{2+}$ because:

• A. The charges of the ions are same
• B. Their radii are the same $(C{a}^{2+}=0.104nm;C{d}^{2+}=0.099nm)$
• C. The $C{a}^{2+}$ ion has a noble gas electronic configuration and $C{d}^{2+}$ ion has 18 electron configuration of its outer shell.
• D. All the above are correct

Answer 1

The correct option is C The $C{a}^{2+}$ ion has a noble gas electronic configuration and $C{d}^{2+}$ ion has 18 electron configuration of its outer shell.

$Ca:\left[Ar\right]4s^{2}C{a}^{2+}:\left[Ar\right]$

So, $C{a}^{2+}$ has a noble gas configuration (i.e. 8 electrons in the valence shell).

$Cd(atomicno.48):\left[Kr\right]5s^{2}4d^{10}C{d}^{2+}:\left[Kr\right]4d^{10}$
$C{d}^{2+}$ has 18 valence electrons or it has pseudo noble gas configuration. Cations with pseudo noble gas configuration have more polarising power than cations with nobel gas configuration.