# What are the elements S, F, Se in order of decreasing electronegativity?

$F , S , S e$
Electronegativity, conceived as $\text{the ability of an atom in a}$ $\text{chemical bond to polarize electron density towards itself}$, INCREASES across a Period, but decreases down a Group. It is a contrived rather than a measured parameter, and there are various scales of which the Pauling Scale is the earliest, and probably still the most useful.
Given what I have said, $F$ is the most electronegative element, followed by the 2nd row chalcogen $S$, and then the 3rd row chalcogen $S e$.