Electronegativity is defined as the tendency of the atom of an element in a chemical compound to attract a shared pair of electrons towards it in a covalent bond.A number of electronegativity scales are present. These include Pauling scale, Milliken-Jaffe scale, Allred Kochow scale etc. Out of these scales, Pauling scale is usually used in which fluorine (the most electronegative element) was arbitrarily assigned a value of 4.0.Electron gain enthalpy is defined as the enthalpy change when a neutral gaseous atom takes up an extra electron to form an anion.Electron gain enthalpy is the tendency of an isolated gaseous atom to accept an additional electron to form a negative ion. Electronegativity is the tendency of the atom of an element in a chemical compound to attract a shared pair of electrons towards it in a covalent bond.Electronegativity is a qualitative measure. It is not a measurable quantity.However, electron gain enthalpy is a quantitative measure. It is a measurable quantity.