now, another exception that exists with ionization energy has to do with the fact, then when in the same period row Group three A. Elements have a lower ionization energy than Group two elements. The reason here being that s sub shell orbital's are most stable, one totally filled. So the most common example for this is between beryllium and boron, boron ISMM or to the right of the periodic table. So you would expect it to have a higher ionization energy. But in fact, that's not true. Here. Beryllium is already in a stable state. It's as orbital electrons are completely filled in. So this orbital's totally filled in and it's very stable. That means if I come in and try to remove an electron, it becomes to s one. We're no longer in a stable state as we want. Remember, as orbital electrons are most stable when they're totally filled in born, on the other hand, is helium to us to to p one. If we could lose this one electron from two p, all we'll be left with is a two s two orbital, which is very stable. So that's what's gonna happen. So it becomes helium to s to once I remove that electron. And now I have an s set off orbital electrons that are totally filled in and therefore it's more stable. As a result, this means that boron has a lower ionization energy than beryllium.