Helium is in group 18 of the periodic table. How is helium different from the other elements in this group? (1 point)

Helium atoms have 2 electrons, while atoms of the other elements in the group all have 18 electrons.

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.

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

1 answer

The correct answer is:

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

This is because helium is unique among the noble gases as it has only 2 electrons and therefore only 2 valence electrons, while the other noble gases (such as neon, argon, krypton, xenon, and radon) have a complete outer shell with 8 valence electrons.