Which element has the highest electronegativity value?

Fluorine possesses the highest electronegativity value among all elements on the periodic table. This characteristic is due to its position in the periodic table; fluorine is located in group 17 (the halogens) and period 2. Being small in size, it has a high effective nuclear charge, meaning that the nucleus has a strong attraction for the electrons in nearby atoms. This leads fluorine to effectively attract electrons towards itself when forming bonds, which is the essence of electronegativity.

Electronegativity values are measured on the Pauling scale, where fluorine is assigned the highest value of approximately 4.0. This indicates that fluorine has a greater tendency to attract electrons compared to other elements. Comparatively, oxygen, chlorine, and nitrogen have lower electronegativity values (around 3.5, 3.0, and 3.0, respectively), making them less effective at electron attraction than fluorine. Fluorine's unique combination of high effective nuclear charge, small atomic radius, and its placement in the halogen group contribute to its status as the most electronegative element.