What Is the Most Electronegative Element?

Comparison of Element Electronegativity Values

Fluorine is the most electronegative element. It has a charge of -1 and readily forms compounds.
Fluorine is the most electronegative element. It has a charge of -1 and readily forms compounds. Original author unknown, Creative Commons License (Wikipedia)

What is the most electronegative element? Electronegativity is one measure of an element's ability to form chemical bonds by attracting an electron. Here is a look at the most electronegative element and an explanation for why it has such high electronegativity.

Why Fluorine Is the Most Electronegative Element

Fluorine is the most electronegative element. Fluorine has an electronegativity of 3.98 on the Pauling Electronegativity Scale and a valence of 1. A fluorine atom needs one electron to fill its outer electron shell and achieve stability, which is why free fluorine exists as the F- ion. Other highly electronegative elements are oxygen and chlorine. The element hydrogen does not have as high of an electronegativity because, although it has a half-filled shell, it readily loses an electron rather than gains one. Under certain conditions, hydrogen does form the H- ion rather than H+.

In general, all elements of the halogen element group have high electronegativity values. The nonmetals to the left of the halogens on the periodic table also have fairly high electronegativities. Elements belonging to the noble gas group have very low electronegativity values because they have complete valence electron shells.

More About Electronegativity

  • Most Electropositive Element: The opposite of electronegativity is electropositivity. Learn which element is the most electropositive or has the lowest electronegativity.
  • Electronegativity Periodic Table: This handy table lists all of the electronegativity values of the elements. The values can be used to predict whether two atoms will form ionic or covalent bonds.
  • Periodic Table Trends: Electronegativity is one of the trends seen in the organization of the elements in the periodic table.