Question

Which element would most likely have a positive electron affinity?

Na

Al

Rb

Ar

Answer 1

Electron affinity has opposite sign than electron gain enthalpy

higher the negative value of electron affinity, more the tendency of an element to accept electron and more the positive value of electron affinity, lower the tendency to accept electrons

As we move from left to right the tendency to gain electrons increases

as we move from top to bottom the tendency to gain electrons decreases

so here Argon will have most negative electron affinity

Rb will have least negative electron affinity

Answer 2

I believe the correct answer from the choices listed above is the first option. The element that would most likely have a positive electron affinity would be sodium, Na. Electron affinity is defined as the change in energy of a neutral atom when an electron is added to the atom.