Question

Which of the following has the highest $1st$ ionization energy?

• A. $Ga$
• B. $Ba$
• C. $Ru$
• D. $F$
• E. $N$

Answer 1

The correct option is D $F$

Elements on the right side of the periodic table have a higher ionization energy because their valence shell is nearly filled. Elements on the left side of the periodic table have low ionization energies because of their willingness to lose electrons and become cations. Thus, ionization energy increases from left to right on the periodic table.So upper right corner elements have highest ionization energies.Fluorine has highest first ionization energy since it has the tendency to gain electron and no tendency to lose the electron from its valence shell.