Ionization energy exceptions

[vivatix]

I am confused about the exemption to the general IE trend in the case of Nitrogen to Oxygen.

According to Khan video, if we draw out the electron configuration, there is repulsion between the paired electrons in the 2p orbital in oxygen, making it easier to remove the electron so the IE is lower than that of nitrogen.

Using the same principle, if we look at the example of S and Cl and drawing out the electron configuration, wouldn't Cl have a lower IE than S? I know the general trend in IE but applying the same logic as explained in the Khan video to this example doesn't work.

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[vivatix]

Does someone have a better explanation to this exception in the general trend?

 

[Cawolf]

Consider that the easiest path to stability is the one that will be taken. Simply stated, there is stability is a full shell of unpaired electrons (Nitrogen) or in a full shell of paired electrons (noble gasses).

For Cl to become stable, it would prefer to gain an electron and fill its shell to become isoelectric with Argon, rather than lose two to become all unpaired. This means that the halogens are excellent electrons acceptors.