Why does Cu+ exist?

Question

What are the correct electron configurations for copper in its ground state, Cu+, and Cu2+ and why are both Cu+ and Cu2+ found in nature (aka why does it sometimes only lose one electron, and other times loses 2)?

Just something I've wondered about, and my chem teacher doesn't know the answer.

I appreciate the first two answers, but please answer the complete question and explain how AND why the electron configuration changes after each electron is removed. That's the part I'm really looking for. Thanks ;-)

Answer 1

Copper as the metalic element has the configuration of:

[Ar] 3d10 4s1

It is the loss of this lone s orbital electron that allows for the formation of Cu+.

However, the energy required to ionize a second electron (one of the 3d electrons) is not very large. The reasons behind this would require a lot of thermodynamic chemistry math (several pages).

If a reaction can only supply enough energy for the first ionization (1st ionization energy: 745.4 kJ/mole), then Cu+ is formed. If additional energy is available (2nd ionization energy: 1957.9 kJ/mole), then the copper can lose another electron and Cu+2 is formed.

Answer 2

Filled shells. Cu2+ is the stabler in air, but Cu1+ has an electron configuration of [Ar] d10. Filled shells (and half-filled shells) enjoy greater than usual stability. However, dropping that second electron isn't too hard to do. Water is a pretty polar solvent that likes highly charged ions, so there's an added incentive to drop that second electron because the Cu2+ is stabilized better by water than Cu1+ (and oxygen in air will gladly take that second electron, or 2Cu1+ will form a Cu2+ and an uncharged Cu in a process called disproportionation). In many proteins (and organic-soluble compounds) where the copper is buried in a more hydrophobic environment that doesn't like highly charged species Cu1+ is the preferred form.

Answer 3

Cu+ is 3d10, which gives it a certain amount of stability, but is generally only found in insoluble salts and in complexes. Otherwise it tends to disproportionate into Cu and Cu2+.