Which element has the highest electronegativity?

Explanation

Fluorine is the most electronegative element on the Pauling scale at 4.0, because it is small and has a high effective nuclear charge, so it attracts bonding electrons more strongly than any other atom. Oxygen at 3.5 is second and chlorine and nitrogen follow at 3.0. Electronegativity increases across a period and decreases down a group, so the maximum lies at the top right, excluding the noble gases.