Electronegativity is the tendency to attract the shared pair of electrons towards itself in a covalent bond. Here, in this article we will discuss about electronegativity and how to apply it.

What is electronegativity

It is the tendency to attract the shared pair of electrons towards itself in a covalent bond. It is represented by kii and is not a measurable quantity.

What factors determine EN

1. Type of hybridisation: sp > sp² > sp³ ( Decreasing order of EN )
2. Oxidation state of element: EN increases with increase in oxidation state. For example: Fe³⁺ > Fe²⁺
3. Nature of substituents: CF3I > CH3I ( EN )

Applications of Electronegativity

1. Determining metallic and non-metallic character : With the increase in EN, non-metallic character increases. For example: F having EN of 4.0 is the most electronegative and non-metallic in nature. Caesium is the lowest EN and most metallic element in the periodic table.
2. Polar and non-polar molecules : More the EN difference between 2 atoms, more is the polarity of the covalent bond. For example: HF, HCl, HBr and HI are polar molecules. Lesser the EN difference between 2 atoms, the molecule becomes non-polar. For example: H2, N2, F2 or Cl2 are non-polar molecules.

Difference between electron gain enthalpy and electronegativity

1. Electron gain enthalpy is the tendency of an isolated gaseous atom to attract an electron. While EN is the tendency of an atom to attract the shared pair of electrons.
2. We can find the value of electron gain enthalpy experimentally but EN is a relative number. We can not determine the value of EN experimentally.
3. Electron gain of an atom is constant but EN of an atom is not constant. Because, EN depends upon hybridisation state, oxidation state and types of substituents attached to the atom.
4. The value of electron gain enthalpy does not change regularly in the period or group. But, EN varies in groups and periods showing some exceptional behaviour.

Check out the following post on variation of IE in periodic table here :

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