Question

Explain why Cu²⁺ is paramagnetic, but Cu⁺ is diamagnetic. (at. no. of Cu = 29)

Answer 1

1. The atomic number of Cu is 29, and its electronic configuration is [Ar] 3d¹⁰ 4s¹.
2. Cu⁺ loses the 4s electron, [Ar] 3d¹⁰; all electrons paired, so diamagnetic.
3. Cu²⁺ loses 4s and one 3d electron, [Ar] 3d⁹; one unpaired electron, so paramagnetic.
4. Magnetic reason: an unpaired electron produces a magnetic moment; paired electrons cancel each other.