Ncert Exercises & Solutions

3.36 The size of isoelectronic species — F–, Ne and Na+ is affected by

(a) nuclear charge (Z)

(b) valence principal quantum number (n)

(d) none of the factors because their size is the same.

Ans- A

The size of an isoelectronic species increases with a decrease in the nuclear charge (Z).

For example, the order of the increasing nuclear charge of F–

, Ne, and Na+ is as follows:

$F^{‐} < N e < N a^{+}$
$Z 9 10 11$

Therefore, the order of the increasing size of $F^{‐}, N e a n d N e a n d N a^{+} i s a s f o l l o w s :$
$N a^{+} < N e < F^{‐}$