ionization energy

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ionization energy

Postby Maldonado3K » Sun Oct 15, 2017 11:54 pm

Why is the ionization energy for oxygen lower than that of either nitrogen or fluorine? (In straight and simple terms)

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Re: ionization energy

Postby Chem_Mod » Mon Oct 16, 2017 11:01 am


The reason why oxygen has a lower ionization energy than nitrogen and fluorine is related to their molecular orbitals which we have yet to discuss in class. Essentially, nitrogen has 5 electrons that occupy its molecular orbitals. This looks like the following:
Screen shot 2017-10-16 at 11.01.58 AM.png

For oxygen, your molecular orbital configuration is as follows:
Screen shot 2017-10-16 at 11.03.32 AM.png

In simplest terms, it is much harder to remove an electron from one of the 2p orbitals of nitrogen because there is a sort of happiness in having 1 electron per orbital. Oxygen, however, can lose an electron, but its orbitals will still be relatively happy because each one of the 2p orbitals is still occupied.

Because fluorine typically exists with a -1 charge, it is like a noble gas and this is the most stable conformation it can have. It would be very challenging to remove an electron from this already very stable molecule.

Hope this helps!

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