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Why is ionization energy of oxygen lower than nitrogen?

Posted: Thu Nov 01, 2018 2:12 pm
by Louise Zhuang
According to periodic trend, I.E. increases from left to right, but O is lower than N

Re: Why is ionization energy of oxygen lower than nitrogen?

Posted: Thu Nov 01, 2018 2:24 pm
by Matthew Choi 2H
Ionization energy is defined as the amount of energy required to remove an electron from a gaseous atom or ion. In order to answer this question, you need to look at the orbitals of both N and O. If you look at the 2p sublevel for N, there is one electron in each orbital. If you look at the 2p sublevel for O, there are two electrons in the first orbital and one in each of the other two orbitals. Since there are two electrons in the first orbital of the O sublevel, 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.

Re: Why is ionization energy of oxygen lower than nitrogen?

Posted: Thu Nov 01, 2018 2:27 pm
by Aaron Ang 4H
Nitrogen has a lower ionization energy than oxygen because nitrogen is half filled which according the Hund's rule, half filled and full filled orbitals are more stable.