Why is helium inert, whereas hydrogen can be both reduced and oxidized?

1 Answer
Sep 12, 2017


Well, because hydrogen and helium, can possess up to 2 valence electrons.....but hydrogen can be both reduced and oxidized.


For hydrogen and helium we fill the #1s# shell, which can accommodate only the TWO electrons. Now hydrogen can be reduced to give hydride anions, and can also be oxidized to give a formal #H^+#.

By contrast, helium has a FULL valence shell, i.e. #1s^2#, which makes it extremely difficult to either reduce or oxidize. And hence helium, like the other closed-shell Noble gases, is a very unreactive customer.