Question

Which one has the positive value of electron affinity: ${O^ - }$ or $F$?
A. ${O^ - }$
B. $F$
C. Both A and B
D. None of the Above

Answer 1

Electron affinity is defined as the change in energy (in $kJ/mole$) of a neutral atom when it is added to an atom to form a negative ion of an atom. In other words, the neutral atom has the potential to gain electrons.

Complete step by step answer:
-We know that the energy of an atom is defined as when the atom loses or loses energy through chemical reactions that cause loss or gain of electrons. A chemical reaction that releases energy is called an exothermic reaction and a chemical reaction that absorbs energy is called an endothermic reaction.
-The energy from an exothermic reaction is negative, thus the energy is negatively indicated, whereas the energy from the endothermic reaction is positive and the energy is given as a positive signal.
-An example that demonstrates both processes is when a person drops a book. When he picks up a book, he gives potential energy to the book.
Well, if you look at the definition, the electron relationship is the tendency to accept only electrons actually.
-Since, O actually is negatively charged, the electron will be more difficult to accept, and the critical coulombic repulsion will make the electron affinity of O more positive than that of O (which is negative).
So, the correct answer is “Option A”.

Note:
In addition to the second electron for the monovalent ${O^ - }$ ion to generate ion ${O^{2 - }}$. This ion is difficult due to electrostatic repulsion of the same charge (between electron and ${O^ - }$ion). The process becomes endoergic.${E_a} = + 780kJ/mol$. Thus the electron affinity of ${O^ - }$ ion is positive. The electron affinity of F is negative because energy is added to the neutral atom.