Final answer:
Neon (Ne) has the highest ionization energy among the given elements because as a noble gas with a full electron shell, it is very stable and resistant to losing electrons.
Step-by-step explanation:
The question is related to ionization energy, which is the energy required to remove an electron from an atom in its gaseous phase. Ionization energy tends to increase across a period and decrease down a group in the periodic table.
Of the given elements - Ca (Calcium), Al (Aluminum), Cl (Chlorine), Ne (Neon), and Ba (Barium) - the one with the highest ionization energy is Neon (Ne).
Neon is a noble gas with a full outer electron shell, which makes it very stable and resistant to losing electrons, therefore, it has a high ionization energy. In contrast, Barium, being lower in the group, would have a lower ionization energy due to its electrons being further from the nucleus and less tightly bound.
The ionization energy refers to the amount of energy required to remove an electron from an atom or ion. It is influenced by factors such as the number of protons, electron shielding, and distance of the outermost electron from the nucleus.
In general, ionization energy tends to increase as you move from left to right across the periodic table and decreases as you move down a group.
Among the given options, the element with the highest ionization energy is E. Ba (Barium). Barium has a greater number of protons and a smaller atomic radius compared to the other elements, which results in a stronger attraction between the nucleus and its outermost electron, requiring more energy to remove.