Question

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 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.

Explanation:

Group 18 elements are noble - gases. Helium has 2 valence electrons filling its first energy level, while other group 18 elements have 8 valence electrons filling their outer energy levels.

Answer:

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