Answer:
The answer is F (Fluor)
Explanation:
The electrons are attracted to the nucleus and it is necessary to provide energy to remove them. Then the ionization energy is the energy needed to remove an electron to a neutral atom, gaseous and in a fundamental state.
By lowering in a group the ionization energy decreases because the electrons are increasingly distant from the nucleus and less attracted to it, which makes it easier to apply less energy to start the electrons from the atom.
In a period, the size of an atom decreases from left to right. So, the attraction generated by the nucleus on atoms is greater, and more energy is needed to tear them away. Then the ionization energy increases.
Taking all of the above into account, it can be said that the ionization energy increases from bottom to top and from right to left in the periodic table.
So, <u><em>the fluor (F) has the greatest first ionization energy.</em></u>