Groups VIA and VIIA in the periodic table have the largest electron affinities. Back Electronegativity Electronegativity is a measure of the ability of an atom in a molecule to draw bonding electrons to itself. The most commonly used scale of electronegativity is that developed by Linus Pauling in which the value 4.0 is assigned to fluorine, the most electronegative element. Lithium, at the other end of the same period on the periodic table, is assigned a value of 1. Electronegativity generally increases from left to right on the periodic table and decreases from top to bottom.
Metals are the least electronegative of the elements.
The Pauling electronegativities for the elements are often included as a part of the chart of the elements. An important application of electronegativity is in the prediction of the polarity of a chemical bond. Because hydrogen has an electrognegativity of 2.1 and chlorine has an electronegativity of 3.0, they would be expected to form a polar molecule with the chlorine being the negative side of the dipole. The hydrogen molecule on the other hand, with zero electronegativty difference, becomes the classic example of a covalent bond .