Electron Affinity Trend

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Electron Affinity Trend

Postby torialmquist1F » Fri Nov 03, 2017 11:05 am

Are there exceptions to the electron affinity trend in the periodic table?

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

Re: Electron Affinity Trend

Postby Nishma Chakraborty 1J » Fri Nov 03, 2017 12:52 pm


A more negative electron affinity corresponds with greater attraction for an electron. Electron affinity tends to increase (as in more energy is released when an electron is added to an atom) as you move up a group on the periodic table. Nobles gases have an electron affinity of approximately zero. There is a tendency for electron affinity to increase as you move left to right across a period. There are exceptions, however, such as group 2A (has a lower electron affinity than 1A) because the addition causes the previously unoccupied p-subshell to gain an electron (which increases instability). Within a period, Carbon has a lower electron affinity than nitrogen, because nitrogen already has half-full p-subshell (which is more stable). A notable exception to the trend with regards to it increasing up a group is Flourine (period 2) which has a lower electron affinity than chlorine (period 3) due to a higher magnitude of electron repulsions in the smaller 2p orbital opposed to chlorine's 3p orbital. Essentially, electron affinity correlates with electron configuration. Atoms with a full subshells (or in some instances half-full subshells) tend to have a lower electron affinity.

Hope this helps!

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