Which of the following has the greatest first ionization energy: F, Li, Rb, or Fr?

A. Li

B. F

C. Rb

D. Fr

B. Flourine

Flourine has one of the highest ionization energies because it is so close to getting a full octet with eight atoms. It doesn't want to lose but rather gain an atom. On the periodic table, ionization energy increases as you head towards the top and to the right.

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, the fluor (F) has the greatest first ionization energy.