Helium is in group 18 of the periodic table. How is helium different from the other elements in this group?

Question

(1 point)
Helium atoms have 2 electrons, while atoms of the other elements in the group all have 18 electrons.
Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Helium atoms have a full outer energy level, while atoms of the
• other elements in the group do not have a full outer energy level.
Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.

Answer 1

The correct statement regarding how helium differs from the other elements in group 18 (the noble gases) is:

Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.

While all noble gases have a full outer energy level, helium, being a smaller atom, has only 2 electrons total, which fill its first energy level, whereas the other noble gases have a full outer shell with 8 electrons in their outermost energy levels.