Oxygen Ionization Energy

[Maylin Garcia]

One of the Achieve questions asks about Oxygen's first ionization energy and I'm confused as to why it has a lower ionization energy when Fluorine has a greater Ionization energy.

[505941102]

Oxygen has a lower ionization energy because it is below/before Fluorine on the periodic table. On the periodic table trend for ionization energy, ionization energy increases from left to right, and bottom to top. Now, since fluorine is more on the right than oxygen on the periodic table, this would indicate it has a higher ionization energy than oxygen.

[Fatima Valenzuela 3k]

While both oxygen and fluorine are in the same period, fluorine has a greater ionization energy because of the higher effective nuclear charge and the absence of substantial shielding effects compared to oxygen.
hope this helps clarify a little!