Polyatomic ions

Polyatomic ions have a systematic naming. The name must contain the participating chemical elements, ordered by the following rules:

1. the electropositive kation before the electonegative anion, e.g. NaCl instead of ClNa, because chlorine is the partner to get the electron here.
2. the parts are ordered by their element number, lower-numbered elements first.
3. If the polyatomic ion consists of more than two elements, the ordering of the parts follows the structure in the molecule. SCN^- instead of CNS^-.

Prefixes

Here are some of the commonly used prefixes for naming of ions:

• Peroxo-: oxygen replaced by peroxo O-O
• Thio-: oxygen replaxed by sulfur