Electron affinity and electronegativity are closely related concepts in chemistry, both of which describe an atom’s tendency to attract electrons. However, they do so in distinct ways and under different circumstances.

Electron Affinity refers to the energy change that occurs when an electron is added to a neutral atom, resulting in the formation of a negative ion. It quantifies the atom’s attraction to the incoming electron. A higher electron affinity indicates a greater desire of the atom to gain an electron. This process is typically exothermic, meaning it releases energy. Nonetheless, not all elements exhibit positive electron affinity; some elements are stable in their natural state and do not readily accept additional electrons.

In contrast, Electronegativity measures an atom’s ability to attract electrons within a chemical compound. It is a dimensionless quantity that is derived from calculations rather than being directly measured. The most electronegative element is fluorine, which is assigned a value of $4.0$ on the Pauling scale. Atoms with high electronegativities tend to attract electrons more strongly than those with lower values.

While both electron affinity and electronegativity involve electron attraction, they are not synonymous. Electron affinity specifically pertains to the energy change associated with the addition of an electron to a neutral atom. Electronegativity, on the other hand, offers a broader perspective on an atom’s electron-attracting ability when it is part of a compound.

Typically, elements with high electron affinities also exhibit high electronegativities, as both properties reflect an affinity for electrons. However, there are exceptions to this correlation due to the differing conditions under which electron affinity and electronegativity are defined. Consequently, while these two properties are interconnected, they are not interchangeable; each provides unique insights into the behavior of atoms within molecules.