Question

Which one of the following groupings represents a collection of isoelectronic species?

(At. Nos .: Cs – 55, Br – 35)

• A. $Na^{+},Ca^{2 +},Mg^{2 +}$
• B. $N^{3 -},F^{-},Na^{+}$
• C. $Be,Al^{3 +}Cl^{-}$
• D. $Ca^{2 +},Cs^{+},Br$

Answer 1

Answer: (B)

$N^{3 -},F^{-},Na^{+}$

Answer 2

Isoelectronic species are the neutral atoms, cations or anions of different elements which have the same number of electrons but different nuclear charge.

Number of electrons in $N^{3 -} = 7 + 3 = 10$

Number of electrons in $F^{-} = 9 + 1 = 10$

Number of electrons in $Na^{+} = 11 - 1 = 10$