JEE MAIN - Chemistry (2003 - No. 49)
The radius of La3+ (Atomic number of La = 57) is 1.06 Å. Which one of the following given values will be
closest to the radius of Lu3+ (Atomic number of Lu = 71) ?
1.60 Å
1.40 Å
0.85 Å
1.60 Å
Explication
Ionic radili $$ \propto {1 \over z}$$
Thus, $${{{z_2}} \over {{z_1}}} \Rightarrow {{1.06} \over {\left( {Ionic\,\,\,radii\,\,\,of\,\,L{u^{3 + }}} \right)}} = {{71} \over {57}}$$
$$ \Rightarrow \,\,\,$$ Ionic radii of $$L{u^{3 + }} = 0.85\,\mathop A\limits^ \circ $$
Thus, $${{{z_2}} \over {{z_1}}} \Rightarrow {{1.06} \over {\left( {Ionic\,\,\,radii\,\,\,of\,\,L{u^{3 + }}} \right)}} = {{71} \over {57}}$$
$$ \Rightarrow \,\,\,$$ Ionic radii of $$L{u^{3 + }} = 0.85\,\mathop A\limits^ \circ $$