Let M be a 3d transition metal and M-1 be the element immediately preceding it in the periodic table. The successive ionization enthalpies ( IE ) of M and M-1 follow the relations given below: IE₁(M) > IE₁(M-1) IE₂(M) IE₃(M) > IE₃(M-1) Identify the metal M .

Step-by-step solution

Let us evaluate the given conditions for the options provided. If M = Mn , then M-1 = Cr . The electronic configuration of Cr is [Ar] 3d^5 4s^1 and Mn is [Ar] 3d^5 4s^2 . For IE₁ : Mn loses an electron from a stable 4s^2 subshell, while Cr loses from 4s^1 . Thus, IE₁(Mn) > IE₁(Cr) . This satisfies the first condition. For IE₂ : Cr^+ is [Ar] 3d^5 (stable half-filled) and Mn^+ is [Ar] 3d^5 4s^1 . Removing an electron from the stable 3d^5 configuration of Cr^+ requires more energy than from the 4s^1 of Mn^+ . Thus, IE