Question

What is correct order of size in each pair given below ?

$Ni$ and $N{i}^{2+}$ :

• A. $Ni$ = $N{i}^{2+}$
• B. $Ni$ < $N{i}^{2+}$
• C. $Ni$ > $N{i}^{2+}$
• D. none of these

Answer 1

The correct option is C $Ni$ > $N{i}^{2+}$

Atomic radius of $Ni$ is more than the ionic radius of $N{i}^{2+}$. 2 electrons are removed from $Ni$ to form $N{i}^{2+}$.The ratio of the number of protons to the number of electrons is higher for $N{i}^{2+}$. than for $Ni$. Hence due to higher effective nuclear charge in $N{i}^{2+}$., the nucleus pulls the electrons to itself to greater extent than that in $Ni$ which results in a smaller ionic radius for $N{i}^{2+}$..Option $C$.