Question 8

Question

Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?

a
Unlike all other elements, hydrogen and helium are gases
b
Unlike all other elements, hydrogen and helium are not considered metals
c
Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons
d
Unlike all other elements, hydrogen and helium have very limited properties

Answer 1

The correct answer is:

c) Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.

Hydrogen has one electron in its outer shell (which is also its only shell) and can hold a maximum of 2 electrons when it forms bonds. Helium has two electrons in its outer shell and is stable because it fills its shell (1s²), making it a noble gas. This characteristic of having a maximum of 2 valence electrons sets them apart from most other elements in the periodic table, which typically have more than 2 valence electrons.

While answer (b) contains a true statement—that both hydrogen and helium are not metals—it does not capture the unique aspect of their electronic configuration.