Answer:
The elements in group 18 are ureactive compared to the elements in group 17.
The elements in group 17 are called the halogens. They are highly reactive nonmetals and hardly occur in free state in nature. They contain seven valence electrons in their outermost shell and are highly electronegative.
The elements in group 18 are unreactive because they have an already filled outermost shell. They are very different from the halogens even though they occur side by side. They occur side by side because they have eight valence electrons and the halogens have seven valence electrons. Recall that elements in the same group have the same number of valence electrons.
They are not Chemically similar at all in any wise. The elements in group 17 and 18 are mostly gases held together by dispersion forces.
Explanation:
