valency of copper

[Bipix]

why does copper show 2 valancies??

[Bloodthunder]

What do you mean shows 2 valencies?

"In chemistry, valence, also known as valency or valence number, is a measure of the number of bonds formed by an atom of a given element."

[Borek]

I guess Bipix means copper in its compounds can be either +1 or +2. Judging from the valence electrons, it should be +1 only.

[Bloodthunder]

Well.... There are Copper (III) and Copper (IV) as well...

[Borek]

Yes, but +1 and +2 are most common, on some levels on education they are the only ones mentioned.