Here's why:
* Copper (Cu): Copper is a transition metal and can have multiple oxidation states. In this case, it has a +2 charge.
* Nitrate (NO₃): Nitrate is a polyatomic ion with a -1 charge.
* Balancing the charges: To balance the charges, you need two nitrate ions (2 x -1 = -2) to counterbalance the +2 charge of the copper ion.
