4.17 Define electronegativity. How does it differ from electron gain enthalpy ?
Electronegativity is the ability of an atom in a compound to attract a bond pair of electrons towards itself. It cannot be measured and it is a relative number.
The electron gain enthalpy, , is the enthalpy change, when a gas phase atom in its ground state gains an electron. The electron gain process may be exothermic or endothermic.
An element has a constant value of the electron gain enthalpy that can be measured experimentally.