Electronegativity and atomic radiusWatch
And it appears that they are not inversely proportional to each other, but I couldn't find any explanation for this (or for the relationship between the two) online.
If the atomic radius is smaller, then the nucleus can attract electrons more easily, and they’ll be held closer and more strongly. These smaller atoms are more electronegative.
If the atomic radius is larger, there are more shells and shielding has a big effect, meaning that the bonding electrons are not held so strongly to the nucleus. These larger are atoms are not very electronegative.
Atomic radius increases down a group.
Electronegativity decreases down a group.