Which of the following is the correct electron configuration for the Copper(II) ion, Cu²⁺ (Z=29)?
[Ar] 3d⁹ 4s²
[Ar] 3d¹⁰ 4s¹
[Ar] 3d⁹
[Ar] 3d⁸ 4s¹
📝 Detailed explanation
A neutral Copper atom is [Ar] 3d¹⁰ 4s¹. When forming a Cu²⁺ ion, electrons are removed from the 4s orbital first, then one from the 3d orbital. This leaves [Ar] 3d⁹.
