An Introduction to Electronegativity and Electron Affinity
Electronegativity: The term electronegativity was first introduced by the scientist named Jöns Jacob Berzelius in the year 1811. In the year 1932, after many discoveries and discussions, Linus Pauling first discovered the property of electronegativity completely and he also created an electronegative scale that depends on the bond enthalpy. This has further helped in establishing the valence bond theory.
The property of attracting a shared pair of electrons towards itself is known as electronegativity. In simple words, electronegativity is the property and the ability to gain electrons from an atom. It ranges from 0.79 to 3.98 on a scale and is denoted by X. The measurement of electronegativity “e” is done in the Pauling scale.
When the atomic number increases, it means that the distance between the nucleus and the valence electron also increases and hence, the electronegativity also rises. Therefore, the atomic number and the location of the electron from the nucleus play a very important role in determining the electronegativity and are the factors that are affecting it. Also, the tendency of attraction of electrons increases with the increase in the number of protons which increases with the increase in the nuclear charge.
When the two electronegative atoms are taken, with the increase in the difference between the electronegativity of the atoms, the polarity of the bond between them also increases. The atom that has the more electronegativity will gain a negative charge on it. The electronegativity usually increases along a period from left to right and decreases on passing through a group that is from up to down. According to this funda, chlorine becomes the most electronegative element and Francium becomes the least electronegative element.
Electron affinity: Electron affinity is the measurement of the amount of energy released when an electron is added by an atom of a molecule to an individual neutral atom which is in a gaseous state that forms a negative ion post the gain of the electron. This property is measured in kilojoules per mole and is denoted by "Eea".
The factors that determine the electron affinity of an atom on an element are the atomic size, the nuclear charge, and the electronic configuration of the molecules or atoms. An electron acceptor has a greater positive electron affinity value while the one with the lower positive value is referred to as an electron donator.
The property of the electron affinity is only used for the atoms and the molecules that are present in the gaseous state. The molecules and the atoms that are present in the solid in the liquid state get changed when they come in contact with other atoms or molecules.
A bunch of electron affinity of elements were used by Robert S Mulliken for developing the electronegativity scale. The theory of electron affinity is also involved in the concept building for chemical hardness and chemical potential.
Electronegativity vs Electron Affinity
Both electronegativity and electron affinity are two different chemical properties that are associated with the elements. The primary difference between electronegativity and electron affinity lies in the fact that electronegativity is the property related to the ability of an electron to attract towards an atom. On the other hand, electron affinity is related to the release of energy whenever an electron tends to get added to an atom. These two properties are often known to be interrelated but they are not interchangeable. Both electronegativity and electron affinity deal with the movement of the electrons. However, electronegativity is the result of the property of attraction, while electron affinity is the result of the change in energy. In this article, we will study electronegativity vs electron affinity in detail.
Understanding the differences between electronegativity and electron affinity is important so that we do not use them interchangeably. Given below is the table that consists of the detailed differences of both terms.
Difference Between Electronegativity and Electron Affinity
Conclusion
The property of electronegativity and electron affinity is associated with the concept of electron gain. While electron affinity is capable of precise measurement and definition, electronegativity is capable of neither of them. For this reason, the electron affinity is present in neutral atoms or atoms in a molecule and the electronegativity only deals with chemically bonded atoms.
FAQs on Difference Between Electronegativity and Electron Affinity for JEE Main 2024
1. What is the definition of electronegativity?
The definition of electronegativity is as follows.
Electronegativity is defined as the property possessed by an atom of an element to attract the electrons from the other elements. Electronegativity is not constant and happens because each element does not tend to attract the electrons with the same amount of force. Some elements would attract the electrons more strongly while others would not.
Hence, different elements tend to possess different electronegativities. An element that tends to possess a stronger ability to attract the electrons has a higher electronegativity while the element that has a weaker ability to attract the electrons is comparatively less electronegative. Hence, the higher the electronegativity, the stronger the electron will be pulled towards the atom.
2. What is the definition of electron affinity?
The definition of electron affinity is explained below
Electron affinity is referred to as the change occurring in the energy of an atom. It is caused generally when there is a release of energy when an electron gets added to it. In more simple terms, electron affinity is known as the energy that is released when an atom gains an electron due to the formation of a negative ion. Electron affinity is related to the exothermic reactions and thus, whenever an electron gets added, it releases some kind of energy.
3. What are the key differences between electron affinity and electronegativity?
Given below are some of the key differences between electronegativity and electron affinity.
- The property due to which the electron gets attracted to the atom is known as electronegativity. On the other hand, electron affinity is related to the release of energy when an electron gets added to an atom.
- Electronegativity is qualitative while electron affinity is quantitative.
- Electronegativity is generally a unitless quantity but is defined in regards to Pauling. Electron affinity, on the other hand, is measured in kJ/mol.
- When an element tends to exhibit a stronger attracting ability, the electronegativity of that element is higher. However, electron affinity is higher if the nuclear charge of the element is higher.
- The value of electronegativity generally lies between 0.7 and 3.98. On the other hand, electron affinity is known to be fixed since the electron releases almost a similar amount of energy when it is added to an atom.
- The most electronegative element known is fluorine while the element having the highest electron affinity is chlorine.
