Which atom on the periodic table would require the most energy to take its electron

An atom on the period table that requires a relatively substantial amount of energy to remove an electron from its outer shell, and thus a high ionization energy would be Fluorine. Due to its small atomic size, and less electron shells, it has a stronger attraction to electrons in its electron shells and thus it is harder to remove the electron from it.

I believe this would be the solution.

What is the gold assay