O versus N Ionization Energy

[Jessica Hu 3L]

What's the reasoning again for Oxygen having a lower ionization energy than Nitrogen?

[Joseph Hsing 2C]

This is because oxygen has one more electron than a half-full orbital as in nitrogen with 3 of 6 p filled. So the energy needed to remove that outlier electron on oxygen will be lower despite the normal trend of ionization energy increasing down a period.

[Arnav Saud 2C]

I believe its caused by the electron-electron repulsion of the extra electron that oxygen has. It weakens electron shielding which lowers its ionization energy.

[jessicaosuna_1F]

From what I gather, it has to do with the electron configuration. Since N has half of its 2p shell filled with electrons it is more stable, whereas Oxygen has an extra electron there so it is more likely to want to lose the electron to become more stable.

[Gicelle Rubin 1E]

I myself am not entirely sure. I just know it has something to do with their electron configuration. Thank you for asking this question since I was also wondering the same thing!

[Valerie Tran 2B]

This is due to an electron being added to an already half full orbital in oxygen, which results in electron-electron repulsion, which will lower the ionization energy. The 2p sublevel for N has one electron in each orbital. O has two electrons in the first orbital and one in each of the other two orbitals. There is greater electronic repulsion in the 2p sublevel for O than N. Therefore, it is easier to remove an electron from the O than the N, and the ionization energy of O is lower than N. Also N is more stable due to half-filled shells

[Aditya Desai 1A]

O is more willing to lose an e- as it gains the half-full symmetry in it's p-orbitals of one e- in each orbital.

[LouiseLin2L]

Generally, ionization energy decreases from top to bottom, and increases from left to right. But, Oxygen has lower ionization energy than nitrogen and fluorine because in oxygen, two of the 2p electrons occupy the same atomic orbital and increased the electron-electron repulsion force.

[Audrey Banzali-Marks 1A]

If O has lower ionization energy because there are 2 paired p electrons and therefore greater repulsion, is this pattern the same for all elements in the same group as oxygen?

[Charlotte McDonough 2B]

Yes that trend should be consistent throughout the other elements in the same group as oxygen. (bc same valence electrons)