Electronegativity, symbol χ, is a chemical property that says how well an atom can attract electrons towards itself. It was first theorised by Linus Pauling in 1932, as part of his valence bond theory. Pauling decided that his way of measuring attraction of electrons was to start with fluorine, the most electronegative element, and give it a value of 4. The electronegativity of all other elements would be determined by comparing them to fluorine.
- "Electronegativity.", IUPAC Compendium of Chemical Terminology