ionization energy

[alexis castro 1B]

Which has the smaller first ionization energy Al or Na. What is a FIRST ionization energy? is it asking for like the original ionization energy before either of these elements start losing or gaining electrons?

[Dabin Kang 1B]

Na has a smaller first ionization energy than Al because Al has a greater nuclear charge than Na, which causes the electrons to be more attracted to the center. Also, ionization energy tends to decrease down a group and increase across a period. The first ionization energy is the amount of energy it takes to remove the outermost electron from a neutral atom in the gas phase.

[Sarah_Wilen]

Like Dabin explained, the ionization energy is the amount of energy it takes to remove the outermost electron from a neutral atom. It decreases a group because the attraction between the valence electrons and nucleus is low due to the increased shielding from the core electrons (or inner electrons).

The reason why the first ionization energy is called "the first" is because there is also second ionization energy. Second ionization energy is the energy needed to remove the second electron from the ion. The energy needed to remove an electron the second time is much greater than the initial. I think that we will mainly be focussing on first ionization energy.

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