Compounds of copper(II) are generally colored, but compounds of copper(I) are not. Explain. The electron configuration for is ; the electron configuration for is . Color is a result of the electron transfer between orbitals. This cannot occur for the completely filled orbitals in

copper I ion has a completely filed d-orbital.

Explanation:

The electron configuration of copper is

29Cu-[Ar] 3d10 4s1

The formation of Cu+ involves the loss of one 4s electron leaving a completely filled d subshell. Colour in transition metal complexes is generally attributed mostly to d-d transition. When bonded to ligands, the d-orbitals are no longer degenerate. They split into sets of orbitals depending on the nature of the crystal field. d-d transition is not possible when the d-orbitals are full hence Cu+ compounds are not coloured.