Question

The manganate and permanganate ions are tetrahedral, due to:
A: The $\pi$ bonding involves overlap of p-orbitals of oxygen with d-orbitals of manganese.
B: There is no $\pi$ – bonding.
C: The $\pi$ bonding involves overlap of p-orbitals of oxygen with p-orbitals of manganese.
D: The $\pi$ bonding involves overlap of d-orbitals of oxygen with d-orbitals of manganese.

Answer 1

Hint: The permanganate ion is not neutral but negatively charged having a -1 charge. The “per” prefix in permanganate is a part of the naming system in case of oxo-anions referring to the oxidation state of the Manganese in the anion. For simplicity, always remember that the prefix “per”, meaning is “above” or “higher” and we should also remember that the oxidation state of manganese in permanganate ion is higher (i.e. more positive) in comparison to manganate.

Complete step by step answer:
Manganate ion:
The manganate ion possesses a negative charge.
The molecular formula of manganate is \[Mn{O_4}^{2 - }\]
The chemical structure of manganate is shown below:

In this manganate ion, two oxygen atoms are having a double bond with the manganese atom while remaining two oxygen atoms are having a single bond.
In this manganate ion, $\pi$ bonds belong to p-orbitals of oxygen and with d-orbitals of manganese (d$\pi$ – p$\pi$).
Permanganate ion:
The permanganate ion possesses a negative charge.
The molecular formula of permanganate is \[Mn{O_4}^ - \].
The chemical structure of permanganate is shown below:

In this permanganate ion, three oxygen atoms are having a double bond with manganese atom and one oxygen atom is having a single bond with manganese atom.
In this permanganate ion, $\pi$ bonds belong to p-orbitals of oxygen and with d-orbitals of manganese (d$\pi$ – p$\pi$).
As a result, the manganate and permanganate ions are tetrahedral, due to the $\pi$ bonding involving overlap of p-orbitals of oxygen with d-orbitals of manganese.

Thus, the correct option is (A).

Note: Manganate consists of manganese in +6 oxidation state while permanganate consists of manganese in +7 oxidation state. Manganate is green in color whereas permanganate is pink in color.