Chapter U1.19, Problem 16E

Interpretation Introduction

Interpretation:

The ion/s with the same number of electrons as present in ${\text{S}}^{2-}$ needs to be identified.

Concept introduction:

Ions with the same number of electrons are known as isoelectronic ions. Sulfide ( ${\text{S}}^{2-}$ ) has 18 electrons which have a similar electronic configuration of inert gas argon.

Answer to Problem 16E

${\text{Cl}}^{-}{\text{, Ca}}^{\text{2 +}}{\text{ and P}}^{\text{3}-}$ have the same number of electrons as present in ${\text{S}}^{2-}$^-.

Explanation of Solution

Cl, Ca and P has atomic number 17, 20 and 15 respectively. A negative charge on an atom is formed after the gain of electron and a positive charge is formed by the loss of an electron.

${\text{Cl}}^{-}$ has one electron more than neutral Cl.

${\text{Ca}}^{2+}$ has two electrons less as compared to neutral Ca atom.

${\text{P}}^{3-}$ has three electrons more as compared to neutral P atom.

Thus, the number of electrons in ${\text{Cl}}^{-}{\text{, Ca}}^{\text{2 +}}{\text{ and P}}^{\text{3}-}$ is 18 which is the same as that of ${\text{S}}^{2-}$.

Conclusion

The atomic number of Na is 11 thus, after removal if 1 electron, the sodium ion is formed. The number of electrons present in sodium ion will be 10. Similarly, the atomic number of oxygen is 8 and after gaining 2 electrons, it forms oxygen ion with a total number of 10 electrons.

Therefore, ${\text{Na}}^{+}{\text{and O}}^{2-}$ do not have the same number of electrons as ${\text{S}}^{2-}$^-.