Question

Anion $O^-$ is isoelectronic with_______

Answer 1

Hint: Isoelectricity is a phenomenon that occurs when two or more molecules have the same structure (positions and connectivities among atoms) and electron configurations, but vary in the specific elements present at specific points in the structure. The concept's significance lies in distinguishing closely related species as pairs or series. Since properties of isoelectronic species are supposed to be consistent and predictable, defining a compound as isoelectronic with one that has already been characterised provides clues to potential properties and reactions.

Complete answer:
Isoelectronicity is a phenomenon that occurs when two or more molecules have the same structure (positions and connectivities among atoms) and electron configurations, but vary in the specific elements present at specific points in the structure. The concept's significance lies in distinguishing closely related species as pairs or series. Since properties of isoelectronic species are supposed to be consistent and predictable, defining a compound as isoelectronic with one that has already been characterised provides clues to potential properties and reactions.
Isoelectronic species are atoms or ions that have the same number of electrons. Isoelectronic species would have the same number of electrons, but the elements would be different. Ions and atoms with the same number of electrons are referred to as isoelectronic species.
Since oxygen has an atomic number of 8, it has a total of 8 electrons.
Consider the anion $O^-$, which has an electron count of 8 + 1 = 9.
Since nitrogen's atomic number is 7, it has a total of seven electrons.
Consider the anion $N^{2-}$, which has a total of 7 + 2 = 9 electrons.

Note:
Isoelectronic species are atoms or ions that have the same number of electrons. Isoelectronic species would have the same number of electrons, but the elements would be different. Ions and atoms with the same number of electrons are referred to as isoelectronic species.