The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is known as electronegativity. There is no specific unit for electronegativity. In the modern periodic table
- As we move across a period from left to right the nuclear charge increases, atomic size decreases and electronegativity value increases.
- As we move down the group there is an increase in the atomic number also nuclear charge and a decrease in the electronegativity value.
- In general metal shows lower electronegativity value compare to the non-metals.
Electron gain enthalpy is defined as the amount of energy released when an electron is added to an isolated gaseous atom. During the addition of an electron, energy can either be released or absorbed. An element has a constant value of the electron gain enthalpy that can be measured experimentally. The unit of electron gain enthalpy may be negative or positive depending on whether the electron is removed or added.