Onium ion

An onium ion is a type of ion (chemical compound with an electric charge) made from adding hydrogen ions to lone pairs on halogen, chalcogen, or pnictogen hydrides. More generally the group also includes ions where the hydrogen is replaced by other atoms, usually organic groups like alkyl. An enium ion is a related type of ion that has two fewer hydrogen atoms and two fewer electrons on the central atom.

 Elements with known onium ions