CBSE Class 12 Chemistry Notes: Periodic Properties – Electron Affinity and Electronegativity

Electron Affinity

The amount of energy released when an electron is added to the outermost shell of one mole of an isolated gaseous atom in its lower energy state is called electron affinity. Electron affinity just defined is actually first electron affinity since it corresponds to the addition of one electron only. In the process of adding further electron, the second electron will be added to gaseous anion against the electrostatic repulsion between the electron being added and the gaseous anion. Sometimes energy instead of being released is supplied for the addition of an electron to an anion.

Electronegativity

It may be defined as the tendency of an atom to attract shared pair of electrons towards itself in a covalently bonded molecules. The numerical value of the electronegativity of an element depends upon its ionization potential and electron affinity values. Higher ionization potential and higher electron affinity values implies higher electronegativity value.

ELECTRONEGATIVITY SCALES
The relative tendency of an atom to attract the shared electron pair towards itself is called electronegativity. This is the property of a bonded atom.
Some arbitrary scales for the quantitative measurement of electronegativities are as under

Factors Affecting the Magnitude of Electronegativity:

PERIODICITY IN ELECTRONEGATIVITY

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