What is the atomic number of an element having ns^1 electronic configuration and belonging to 3d transition series?

Step-by-step solution

The 3d transition series belongs to the 4th period, so n=4 . The general electronic configuration of the 3d transition series is [Ar] 3d¹⁻¹⁰ 4s¹⁻² . Elements with an ns^1 (i.e., 4s^1 ) configuration in this series are Chromium (Cr) and Copper (Cu) due to the extra stability of half-filled and fully-filled d-subshells. The electronic configuration of Cr ( Z=24 ) is [Ar] 3d^5 4s^1 . The electronic configuration of Cu ( Z=29 ) is [Ar] 3d¹⁰ 4s^1 . Thus, the atomic numbers are 24 and 29. Answer: 24 and 29