[kataklysmic]

would anyone be able to explain the electron affinity trend in the second period to me (Li to F)? i understand the basic concept of large amounts of energy being given off when flourine or oxygen gains an electron as a result of it's high electronegativity, but why does nitrogen have such a low electron affinity compared to carbon? if someone could explain the trend it would help me out so much.

[Yggdrasil]

What's carbon's electron configuration?  What's nitrogen's electron configuration?  Why might adding an electron to carbon be favorable and why might adding an electron to nitrogen be unfavorable?

[kataklysmic]

i think i understand it now. it has to do with the number of paired electrons in the p orbital of nitrogen.

[english]

It actually takes energy to attain a more stable configuration, which is low spin configurations for some atoms, high spin for others.


By high spin I mean number of unpaired electrons is high.



I can't remember what transition elements have high spin configurations.  Can anyone remind me?

I'm thinking of copper for some reason.

[Yggdrasil]

Electron configurations with completely full shells and half-full shells exhibit an increased stability over other electron configurations.  Therefore, nitrogen (1s²2s²2p³), which already has a half full 2p shell, will not want to eliminate the stability of a half-full shell by gaining an electron.  Therefore, it has a lower electron affinity than expected by electronegativity alone.  On the other hand, carbon (1s²2s²2p²) is one electron away from the stability of a half-full shell; therefore, it has extra "incentive" to seek out an extra electron and obtain a half-full 2p shell.  So, carbon exhibits a higher electron affinity than expected by electronegativity alone.  In much the same way, oxygen (1s²2s²2p⁴) will want to get rid of an electron in order to obtain a half-full 2p shell, so its ionization potential will be lower than expected.

g english:  High spin/low spin in transition metal complexes is dictated by the ligands as well as in which row the metal sits.  But, what does this have to do with the question?

[english]

Ahh I mixed things I meant high/low multiplicity.