What does ionization energy remove from an atom of an element?

Answer 1

Ionization energy and electron affinity for cations and anions, respectively.

Answer 2

Ionization energy is the energy required to remove one electron from an atom's outer shell. (The atom must be in its neutral state)

First ionization energy is the energy required to remove the first electron, second ionization energy is the energy required to remove the second electron (after the first has already been removed) etc.

First ionization energy tends to increase across a row, as the number of electrons within the outer shell also increases(the more "full" an outer shell, the more difficult it is to remove single electrons). The reason for this is that as the number of electrons in the outer shell increases, so too does the "Z" effect (the attraction between the nucleus and the valence (outer) electrons).

First ionization energy tends to decrease as you go down the Periodic Table. The reason for this is that there are more electron shells, and thus, less attraction between the nucleus and the valence electrons. The more electron shells there are, the more shielding occurs between the nucleus and the outermost electrons. Thus, it is easier to remove electrons.

Though this trend is not 100% accurate, it is a descriptive general trend.

Answer 3

An electron.

Answer 4

an electron