Question

A stable dipositive ion and a dinegative ion are isoelectronic with an octet configuration in the second shell of their atoms. Identify the preceding and succeeding elements and write their electronic configurations.

Answer 1

1. Ions are charged particles that can be both positive and negative.
2. Dipositive ions: Dipositive ions are ions that have two units of positive change.
3. Dinegative ions: Dinegative ions are ions that have two units of negative change
4. So, let us consider dipositive ion be $X^{+2}$ and dinegative ion be $Y^{-2}$.
5. Since the octet in the 2^nd shell is $2,8$. So, the no. of electrons in $X=10+2=12$ and; no. of electrons in $Y=10-2=8$.
6. Hence, the atomic number of $X=12$; i.e the element is magnesium and its electronic configuration is $2,8,2$.

Hence, the atomic number of $Y=8$; i.e the element is oxygen and its electronic configuration is $2,6$.