1. Start with the neutral copper atom:
* Copper (Cu) has an atomic number of 29, meaning it has 29 electrons.
* Its full electron configuration is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰
2. Remove electrons for the ion:
* Copper(II) ion (Cu²⁺) has lost two electrons.
* We remove the electrons from the highest energy levels first, which are 4s and then 3d.
3. The final electron configuration:
* The full electron configuration of Cu²⁺ is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹
Important Note: While the standard order of filling orbitals is based on increasing energy levels, the 3d orbital in copper is actually slightly lower in energy than the 4s orbital due to a phenomenon called "electron-electron repulsion." This is why copper's neutral atom has a configuration of 4s¹ 3d¹⁰ rather than 4s² 3d⁹. However, when copper loses its two electrons to form Cu²⁺, it does so from the highest energy level (4s) first.
