Key Difference: Electronegativity is a chemical property that decides the tendency of an atom to attract electrons in a covalent bond. It is a property that can not be directly measured. Electron affinity of an atom is the amount of energy the atom exerts when an electron is added a neutral atom or molecule to make it into a negative ion. In solid state physics, electron affinity is also known as the energy required to move an electron from the bottom of the lowest conduction band to a stationary state in the nearby vacuum.

Electronegativity and Electron Affinity are two different terms that people come across when dealing with atoms and bonds. Basic science taught us that atoms make bonds by borrowing electrons, giving away electrons or sharing electrons. These electrons are responsible for forming many different things that we know and use in daily life including basic necessity such as water. When we talk about bonds, electronegativity and electron affinity play a huge part. These two terms are often confused because of their similarity but in actuality, they refer to two different things and have many differences.

Electronegativity is a chemical property that decides the tendency of an atom to attract electrons in a covalent bond. It is a property that can not be directly measured and is affected by the atom’s atomic number and the distance that its valence electrons reside from the charged nucleus. Hence, the higher the electronegativity of a compound or an element, the more it attracts electrons towards it. The concept of electronegativity was proposed by Linus Pauling in 1932 as an addition to the valence bond theory. Since electronegativity cannot be directly measured, it is calculated using the atom’s atomic and molecular properties such as the nuclear charge and the number/location of other electrons present in the atomic shells.

Electron affinity of an atom is the amount of energy the atom exerts when an electron is added a neutral atom or molecule to make it into a negative ion. In solid state physics, electron affinity is also known as the energy required to move an electron from the bottom of the lowest conduction band to a stationary state in the nearby vacuum. When an electron is added to an atom or molecule, the more energy it releases the more readily an atom becomes into an ion. Electron affinity is a property that can be readily measured using scientific measures such as the energy released after an electron was added.

Although they are similar to each other and measure the tendency of an atom to attract electrons; they bear few differences. One major difference is that the concept of electronegativity is not quantifiable and is primarily used to explain covalent bonds and bond polarity. However, electron affinity is quantifiable and can easily be measured by measuring the amount of energy released when an electron is added. Electronegativity also helps understanding the location of the bonding pair of electrons. Electronegativity deals with individual atoms, while electron affinity deals with atoms in a molecule. Electronegativity is also a property, while electron affinity is a measurement. Electronegativity values can also change depending on the molecule that it is bonding to, while electron affinity does not change.

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