halogens
The Halogens The halogens are in group 7 of the periodic table devised by Dimitri Mendeleev and have 7 electrons in their outer shell. ... All of the halogens exist as diatomic molecules when elements with one covelant bond between the molecules. All halogens displace each other when they are more reactive (have a stronger electronegativity). ... It is the element at the top of group 7 and will displace all of the halogens.