Here's why:
* Anions are negatively charged ions, meaning they have gained electrons.
* The suffix "-ide" is used to indicate that an element has become an anion.
Examples:
* Chloride (Cl-)
* Sulfide (S2-)
* Nitride (N3-)
* Oxide (O2-)
Exceptions:
There are some exceptions to this rule, especially for polyatomic ions (ions made of multiple atoms). For example:
* -ate (e.g., Sulfate (SO42-), Nitrate (NO3-), Phosphate (PO43-))
* -ite (e.g., Sulfite (SO32-), Nitrite (NO2-), Phosphite (PO33-))
However, the "-ide" suffix remains the most common way to denote an anion in chemistry.