In the first transition series, the melting points of the metals generally increase with atomic number, reach a maximum, and then decrease regularly. However, one specific metal situated near the middle of the series exhibits an anomalous dip in its melting point. What is the ground state outer electronic configuration of the metal showing this anomalous dip?

Step-by-step solution

In the first transition series ( 3d series), the melting point generally increases as the number of unpaired d -electrons increases, reaching a maximum at chromium (Cr, 3d⁵ 4s¹ ). However, manganese (Mn) and technetium (Tc) in the 4d series show an anomalous dip in their melting points despite having a d⁵ configuration. The metal in the first transition series that exhibits this anomalous dip is manganese (Mn). The ground state outer electronic configuration of manganese is 3d⁵ 4s² . Answer: 3d⁵ 4s²