Question

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

Answer 1

`F, S, Se`

Explanation:

Electronegativity, conceived as `"the ability of an atom in a"` `"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 `Se`.