Question

Select the correct order of ions with respect to their ionic radii.

• A. $Y^{3+}<L{u}^{3+}<E{u}^{3+}<L{a}^{3+}$
• B. $L{u}^{3+}<Y^{3+}<E{u}^{3+}<L{a}^{3+}$
• C. $L{u}^{3+}<E{u}^{3+}<L{a}^{3+}<Y^{3+}$
• D. $L{a}^{3+}<E{u}^{3+}<L{u}^{3+}<Y^{3+}$

Answer 1

The correct option is A $Y^{3+}<L{u}^{3+}<E{u}^{3+}<L{a}^{3+}$

We know that as we move down the group, radii increases and as we move across a period, radii decreases. The correct order of ionic radii is as follows:

$Y^{3+}<L{u}^{3+}<E{u}^{3+}<L{a}^{3+}$

This is because $Eu$ and $Lu$ are the members of the lanthanide series which have smaller radii than the transition metals.

$Y^{3+}$ ion has a lower radius as comparison to $L{a}^{3+}$ because it lies immediately above it in the periodic table and hence, it has a lower effective nuclear charge and a larger size.