Question

By what property is electronegativity determined?

Answer 1

Electronegativity is largely a function of nuclear charge.

Explanation:

`"Electronegativity"` is defined as the ability of an atom involved in a chemical bond to polarize electron density towards itself. Electronegativity tends to increase across a Period (from left to right as we face the Table) and decrease down a Group.

Incomplete electron shells tend to shield nuclear charge very imperfectly. This is manifested by the well-known contraction in atomic radii as we go from element to element across a Period from left to right.

And thus fluorine, to the right of the second Period, `Z=9`, is more electronegative than hydrogen, `Z=1`.