Again, it has to do with more advanced topics.
A simple explination is that nature favors half filled and then filled electron sublevels.
Cu will have a charge of 2+ or 3+, most likely. The transition metals are kind of funky like that.
If I remember correctly, silver has a 1+ because of its size, it only likes to let go of one of its atoms. It becomes more stable in its ion form because of that half filled s sublevel.
Feel free to check me on this, I'm pretty sure that I got part of that explination wrong.