Question

Explain the exceptional electronic configuration of Cu.

Answer 1

1. Chromium's electronic configuration is exceptional because it prefers a half-filled 3d subshell for extra stability.
2. Instead of filling 4s² and 3d⁴ (expected), it has 4s¹ and 3d⁵.
3. This reduces electron repulsion and increases stability by having a half-filled 3d and half-filled 4s subshell.
4. Similarly, copper has an unusual configuration of 4s¹ and 3d¹⁰ for a fully filled 3d subshell.
5. These configurations are more stable than expected due to electron-electron interactions and symmetry.