Electronegativity and electron affinity are the two chemical properties associated with elements. The major difference between electronegativity and electron affinity is that electronegativity is the property associated with the attracting ability of electron towards an atom. As against, electron affinity is associated with the release of energy when an electron is added to an atom. These two properties are said to be interrelated but are not interchangeable.
What is an Electron?
Electron is known to be a subatomic particle that is of negative polarity. It is sometimes known as a negatively charged particle of an atom. It is present in a bounded state or free state in an atom. This means that an electron inside an atom can be either bounded to its nucleus or unbounded.
Electrons in an atom are generally present in spherical shells of different radii.
The movement of an electron from an atom to another causes a current to flow through that material. An electron has a charge of value 1.69 *10-19 C.
Electronegativity and electron affinity both are associated somewhat with the movement of electrons. Here in this article, we will see, the basis of differentiation between electronegativity and electron affinity.
Content: Electronegativity Vs Electron Affinity
Comparison Chart
| Basis for Comparison | Electronegativity | Electron Affinity |
|---|---|---|
| Basic | Attracting tendency of atom. | Tendency of releasing energy when electron is added. |
| Nature | Qualitative | Quantitative |
| Unit | Pauling | KJ/mol |
| Associated with | Isolated atom | An atom in a molecule |
| Maximum value | When attracting force is high | When nuclear charge is more. |
| Example | Most and least electronegative element are Fluorine and Francium respectively. | Highest and lowest electron affinity elements are Chlorine and Neon respectively. |
Definition of Electronegativity
The property of an atom of an element to attract electrons is known as electronegativity. Basically, it is not constant and this is due to the fact that every element does not attract the electron with the same force. As some elements attract the electrons strongly while others don’t.
Thus, different elements have different electronegativity. An element that possesses a strong attracting ability has high electronegativity while the one that has a weak attracting ability is less electronegative. Thus, the greater the electronegativity, the more strongly the electron is pulled towards the atom.
A covalent bond between 2 atoms with the same electronegativity level shares the electron equally.
It was proposed in 1932 by Linus Pauling.
Definition of Electron Affinity
The change in the energy of an atom which is generally caused by the release of energy when an electron is added to it is known as electron affinity. More simply, the energy released when an electron is gained by the atom because of the formation of negative ion is called electron affinity. Electron affinity is related to an exothermic reaction because when an electron is added then it gives off energy.
Now, you must be thinking that how electron affinity varies?
So, an atom with a smaller size has a higher electron affinity. The reason behind this is that, in a small atom, the electron in the outermost shell is closely bonded to the nucleus in comparison to a large atom.
We are saying this on the basis that when an electron is closely bounded to an atom then a large amount of energy is required to free it. In a similar way, when an electron is added to such an atom then a high amount of energy is released. Thus, electron affinity will be higher. Electrons are generally transferred from an atom to another and electron affinity is necessary for the transfer of electron.
Key Differences Between Electronegativity and Electron Affinity
- The property by which an electron gets attracted to an atom is electronegativity. While the property that allows, release of energy when an electron is added to the atom is electron affinity.
- Electronegativity is of qualitative nature whereas electron affinity is quantitative in nature.
- Electronegativity is a unitless quantity however is generally defined in terms of Pauling, the one who proposed the concept. However, electron affinity is measured in KJ/mol.
- Electronegativity is higher when the element exhibits strong attracting ability, whereas electron affinity is higher when the nuclear charge is higher.
- The value of electronegativity lies between 0.7 to 3.98. While electron affinity is said to be fixed because the electron releases almost similar energy whenever added to an atom.
- Fluorine is known to be the most electronegative element whereas chlorine is known to be an element with the highest electron affinity.
Conclusion
So, this discussion concludes that both electronegativity and electron affinity is associated with the movement of electron however, as electronegativity is the result of attracting, electron affinity is the result of a change of energy.