How many elements is copper (II) hydroxide composed of? How many atoms?

$C u {\left(O H\right)}_{2}$, 3 elements, 5 atoms.
To derive the formula of copper(II) hydroxide, you need to balance the positive charge of the copper(II)-ion $C {u}^{2 +}$ with the negative charge of the hydroxide-ion $O {H}^{-}$. You'll need two $O {H}^{-}$'s to balance, hence: $C u {\left(O H\right)}_{2}$