1. Tardigrade
  2. Question
  3. Chemistry
  4. Which of the following orders of ionic radii is correctly represented?

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. Which of the following orders of ionic radii is correctly represented?

AIPMTAIPMT 2014Classification of Elements and Periodicity in Properties

Solution:

(No option is correct.)
(a) $H^- > H^+ > H$
It is known that radius of a cation is always smaller than that of a neutral number of orbits. Whereas, the radius of anion is always greater than a cation due to decrease in effective nuclear charge. Hence, the correct order is
$ H^- > H^+ > H$
(b) $ Na^+ > F^- > O^{2-}$
The given species are isoelectronic as they contain same number of electrons. For isoelectronic species
Ionic radii $\propto \frac{1}{\text{atomic number}}$
Ion: $ Na^+ > F^- > O^{2-}$
Atomic number: 11 9 8
Hence, the correct order of ionic radii is
$ O^{2-} > F^- > Na^+$
(c) Similarly, the correct option is
$ O^{2-} > F^- > Na^+$
(d) Ions $Al^{3+} > Mg^{2+} > N^{3-}$
Atomic number $ 13 \, \, 12 \, \, \, 7 $
Hence, the correct order is, $N^{3-} > Mg^{2+} > Al^{3+}$