Electron configuration for the copper (II) ion

Answer 1

The copper(II) ion, is simply elemental copper (Cu), with 2 electrons taken away.

Cu has atomic number 29, so it has 29 electron.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁹

Taking 2 valence electrons away, we end up with 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹ = configuration for Cu²⁺