which name of Zn(OH)2 compound is right? Zinc Hydroxide, or Zinc(||) Hydroxide ?

Question

i know that Zinc is one of the metals cations, but i don't know if it's a transition metal too. I asked my professor once and he preferred the second one Zinc(||) Hydroxide, but after i researched it i found out that the name Zinc Hydroxide is right.

So i'm confused. 

Answer 1

Since Zn can have only 1 valence of 2+, you need not use the Stock system of Roman numerals.  Zn is, in fact, a transition metal, but it is one of the few that have only a single valence (Sc and Ag are other examples).  So, the correct name for Zn(OH)2 is simply zinc hydroxide.