Maar die plaatsing wordt zelden gebruikt buiten de context van elektronenconfiguratie: toen de edelgassen ontdekt werden rond 1900, werden ze "groep 0" genoemd, omdat er toen nog geen chemische reactiviteit bekend was in die elementen, en helium werd bovenaan deze groep geplaatst, omdat het ook chemisch inert was.
While such a placement is common for hydrogen, it is rarely used for helium outside of the context of electron configurations: When the noble gases (then called "inert gases") were first discovered around 1900, they were known as "group 0", reflecting no chemical reactivity of these elements known at that point, and helium was placed on the top of that group, as it did share the extreme chemical inertness seen throughout the group.WikiMatrix WikiMatrix