each of the elements in group 18 end with the suffix ~on, instead of the suffix for the rest of the periodic table, ~ium (helium is the exception to this rule due to historical precedent).

ACS Publications journals Editors are joining in the IYPT celebrations with a series of videos exploring their relationship with the table. Is the periodic table hanging ... Discovery of Helium in ...

Atoms of group 7 elements have seven electrons in their outer shell, and atoms of group 0 elements, except helium ... study guide on groups in the periodic table for more information.