Of the elements below, which has the most negative electron affinity?
A. Fluorine
B. Hydrogen
C. Chlorine
D. Sodium
E. Oxygen
The Correct Answer and Explanation is:
The element with the most negative electron affinity among the options provided is A. Fluorine.
Explanation of Electron Affinity
Electron affinity refers to the amount of energy released when an electron is added to a neutral atom in the gas phase, forming a negative ion. A more negative electron affinity value indicates that the atom releases more energy upon gaining an electron, making it more favorable for that atom to accept an electron.
Fluorine has the highest (most negative) electron affinity of all the elements. This is primarily due to its high electronegativity and small atomic size. Being in Group 17 (the halogens), fluorine has a strong tendency to gain an electron to achieve a stable noble gas configuration, specifically the electron configuration of neon. When a fluorine atom gains an electron, it becomes F⁻, and the energy released during this process is significantly high because the added electron experiences a strong attraction to the nucleus due to the high effective nuclear charge of fluorine.
In comparison, chlorine also has a high electron affinity, but it is less negative than that of fluorine. This is attributed to the larger size of chlorine atoms, which results in increased electron-electron repulsion in its outer shell when gaining an electron, thus releasing less energy than fluorine.
Hydrogen, while it does have a negative electron affinity, is less negative than that of fluorine and chlorine. Sodium has a very low electron affinity, as it is more favorable for sodium to lose an electron than to gain one. Oxygen also has a negative electron affinity, but it is still not as negative as fluorine’s.
In summary, the most negative electron affinity occurs in fluorine, making it the element that most readily accepts an electron, releasing significant energy in the process.