Which element does not have the same number of electrons in its outermost shell as the other elements in its group?

1 answer

The element that does not have the same number of electrons in its outermost shell as the other elements in its group is helium (He).

In Group 18 of the periodic table, also known as the noble gases, all elements have a full outermost shell except for helium. Helium only has 2 electrons in its outermost shell, while the other elements in Group 18 have 8 electrons in their outermost shell.