Question

Which of the following metal is expected to have the highest third ionization enthalpy?

• A. $Cr(Z=24)$
• B. $V(Z=23)$
• C. $Mn(Z=25)$
• D. $Fe(Z=26)$

Answer 1

The correct option is C $Mn(Z=25)$

The electronic configuration of these metals is:

Cr : $\left[Ar\right]3d^{5}4s^1$

V : $\left[Ar\right]3d^{3}4s^2$

Mn : $\left[Ar\right]3d^{5}4s^2$

Fe : $\left[Ar\right]3d^{6}4s^2$

The third ionization enthalpy of Mn means removal of electron from the stable configuration of $3d^5$. The metal having the highest third ionization enthalpy is Mn.