Q. Of the following sets which one does not contain isoelectronic species ?
AIEEEAIEEE 2005Structure of Atom
Solution:
Species Electron in central element Electrons in other element Charge gained Total $BO^{3-}_{3}$ $5$ $3\times8 = 24$ $+\,3$ $32$ $CO^{2-}_{3}$ $6$ $3\times8 = 24$ $+\,2$ $32$ $NO^{-}_{3}$ $7$ $3\times8 = 24$ $+\,1$ $32$ $SO^{2-}_{3}$ $16$ $3\times8 = 24$ $+\,2$ $42$ $CN^{-}$ $6$ $7$ $1$ $14$ $N_{2}$ $7$ $7$ $0$ $14$ $C^{2-}_2$ $6$ $6$ $+\,2$ $14$ $PO^{3-}_{4}$ $15$ $4\times8 = 32$ $+\,3$ $50$ $SO^{-}_{4}$ $16$ $4\times8 = 32$ $+\,2$ $50$ $CIO^{2-}_{3}$ $17$ $4\times8 = 32$ $+\,1$ $50$
Thus (a) $BO^{3-}_3,\, CO^{2-},\, NO_3$ are isoelectronic.
(b) $SO^{2-}_3,\, CO_3^{2-},\, NO_3^-$ are not isoelectronic.
| Species | Electron in central element | Electrons in other element | Charge gained | Total |
|---|---|---|---|---|
| $BO^{3-}_{3}$ | $5$ | $3\times8 = 24$ | $+\,3$ | $32$ |
| $CO^{2-}_{3}$ | $6$ | $3\times8 = 24$ | $+\,2$ | $32$ |
| $NO^{-}_{3}$ | $7$ | $3\times8 = 24$ | $+\,1$ | $32$ |
| $SO^{2-}_{3}$ | $16$ | $3\times8 = 24$ | $+\,2$ | $42$ |
| $CN^{-}$ | $6$ | $7$ | $1$ | $14$ |
| $N_{2}$ | $7$ | $7$ | $0$ | $14$ |
| $C^{2-}_2$ | $6$ | $6$ | $+\,2$ | $14$ |
| $PO^{3-}_{4}$ | $15$ | $4\times8 = 32$ | $+\,3$ | $50$ |
| $SO^{-}_{4}$ | $16$ | $4\times8 = 32$ | $+\,2$ | $50$ |
| $CIO^{2-}_{3}$ | $17$ | $4\times8 = 32$ | $+\,1$ | $50$ |