In ionic compounds, the sum of charges of all cations and anions must be zero.

This is because ionic compounds are electrically neutral. The positive charges from the cations must balance out the negative charges from the anions.

Here's a simple example:

* Sodium chloride (NaCl)

* Sodium (Na) has a +1 charge.

* Chlorine (Cl) has a -1 charge.

* The formula NaCl represents one sodium ion and one chloride ion, ensuring a net charge of zero: (+1) + (-1) = 0.