The group 17 elements which has the largest monatomic ions is
referred to as Astatine.
What are Halogens?
These are chemical elements which belong to group 17 of the
periodic table. They are highly reactive because of the
presence of seven electrons in their valence shell which require
only one electron to complete its octet.
They form mono-atomic ions and the one with the largest is
Astatine as a result of its high density and radioactive
properties.
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