# Question #f93b8

Jun 22, 2016

Here's what I got.

#### Explanation:

The trick here is to realize that because you're dealing with two ionic compounds, $\text{X}$ cannot be a metal, i.e. it cannot be located in group 1 or group 2 of the periodic table.

In other words, you need $\text{X}$ to accept electrons from copper to form anions, which are negatively charged anions. By comparison, copper will form cations, which are positively charged ions.

Likewise, $\text{X}$ cannot be located in group 13 because elements located in this group form $3 +$ cations.

The only valid possibility is to have $\text{X}$ located in group 17, the halogen group. In ionic compounds, halogens form $1 -$ anions because they only need one electron to complete their octet.

It's worth mentioning that copper, which is a transition metal, can have more than one valence. On the other hand, element $\text{X}$, which is a main-group element, cannot have more than one valence.

You will thus have

${\text{CuX " -> " Cu"^(+) + " X}}^{-}$

and

${\text{CuX"_2 -> " Cu"^(2+) + " X}}^{-}$