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

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

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

D _ 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.

The correct answer to the question is option C. Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.

Group 18 of the periodic table are known as the noble gas family. Their outermost shell is completely filled.

Members of the group 18 includes:

1. Helium (He)

2. Neon (Ne)

3. Argon (Ar)

4. Krypton (Kr)

5. Xenon (Xe)

6. Radon (Rn)

Among this group, only Helium (He) has a valence electron of 2.  Other members of the group has a valence electron of 8.

Helium is part of the group 18 because its outermost shell is completely filled by its 2 electrons.

Therefore, option C gives the right answer to the question as helium only have 2 valence electrons while other members of the group has 8 valence electrons.

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answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.