ELECTRON AFFINITY

[Tim Foster 2A]

How are we supposed to know how electron affinity changes as you go down a group on the periodic table? I know that (generally) electron affinity increases from left to right across the table, but how should I know that Na has a lower EA than Li, for example?

[Emily Duggan 1F]

Electron affinity decreases down a group because as the atom radius increases, the valence electrons are further from the nucleus so those outer electrons feel a reduced electrostatic attraction (due to shielding of inner electrons), therefore the outer electrons are easier to remove or add. That is why the periodic trend is the same for electron affinity and ionization energy. Hope this helps!

[Shannon Wasley 2J]

In relation to increasing electron affinity across a row, how would the electron affinities of the halogens compare to the electron affinities of the noble gases, if they are in the same row. For example, how would Chlorine and Argon relate in terms of electron affinity?

[Connor Kelligrew 2D]

Also note that the atom wants to reach a stable, full valence shell, so whether that is easier by losing or gaining electrons will lead to a lower or higher electron affinity respectively.

[Michael Lee 2I]

Are there any exceptions to the electron affinity increasing across the period?

[JonathanLam1G]

Are there any exceptions to the electron affinity increasing across the period?

The first couple elements in group 5 (N, P, As) have lower electron affinities than the group 4 counterparts in their row (C, Si, Ge), because the group 4 elements want an extra electron to complete their half p shells and become paramagnetic, while group 5 elements are pretty stable with a half-filled p shell, and therefore, wouldn't have as strong of an affinity for electrons.

[Yixin Angela Wang 2H]

In response to Shannon's question, I think that in general, the noble gases should have an electron affinity of basically 0 because they already have a full valence shell and thus would not tend to try to gain or lose electrons. Halogens would have a high electron affinity because they really want to gain one electron to make a full valence shell.

[Ilan Shavolian 1K]

In response to Shannon's question, I think that in general, the noble gases should have an electron affinity of basically 0 because they already have a full valence shell and thus would not tend to try to gain or lose electrons. Halogens would have a high electron affinity because they really want to gain one electron to make a full valence shell.

I think its actually less than zero because it requires energy to add an electron.