There's no single formula for "copper 2". You're likely thinking of a copper ion with a +2 charge, which is written as Cu²⁺.

Here's why:

* Copper is a transition metal, meaning it can have multiple oxidation states (charges).

* Copper(II) or Cu²⁺ specifically refers to the copper ion with a +2 charge.

To find a specific formula, you need to know what copper(II) is combined with:

* Copper(II) oxide: CuO

* Copper(II) sulfate: CuSO₄

* Copper(II) chloride: CuCl₂

* Copper(II) nitrate: Cu(NO₃)₂

Let me know if you have a specific compound in mind, and I can help you find the formula!