Question

What do electronegativity values represent?

Answer 1

Electronegativity is conceived to be the ability of an atom in a chemical bond to polarize electron density towards itself.

Explanation:

There are various scales, of which the Pauling Scale is the earliest, and most widely used. Pauling drew his values from ionization enthalpies, atomic size, and electron affinities. He then jiggered around with the parameters until he got a scale that had simple numbers that fell between the `0-4` range.

Given the definitions, electronegativities reasonably increase ACROSS a Period (left to right as you face the table), because nuclear charge increases. Electronegativities decrease DOWN a Group. Why?