The electronic configuration of Cu2+ is [Ar]3d^9 and Cu+ is [Ar]3d^10. Why Cu2+ is more stable?

Question

The electronic configuration of Cu2+ is [Ar]3d^9 and Cu+ is [Ar]3d^10.  Why Cu2+ is more stable?

cattbarf · Accepted Answer

Good question.   Copper itself is 3d10/4s1.   To go to the Cu+ ion means you empty out the 4s shell.   In the buildup of elements, the 4s shell fills first, then the 3d shell.  So the 3d9 configuration must occur for the Cu+2, since there are no low-energy filled orbitals to lose electrons.  

 That said, it really does not address the stability question.  It may well be that the stability (a function of electropositivity relative to the ambient environment) is NOT a function of electron structure at all.   If it is, one would expect that that an alternate 3d8/4s1 or 3d7/4s2 are somewhat higher energy.

Anonymous · Answer

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The electronic configuration of Cu2+ is [Ar]3d^9 and Cu+ is [Ar]3d^10. Why Cu2+ is more stable?

2 Answers