Question

Which one has least ionization potential?

• A. Neon
• B. Nitrogen
• C. Oxygen
• D. Fluorine

Answer 1

The correct option is B Nitrogen

Nitrogen, Oxygen, Fluorine , Neon have respectively 5, 6, 7 , 8 electrons in their outermost orbit. Along a period as the number of valence electrons increases, the nuclear charge of the atom increases and so the nuclear force of attraction on these valence electrons also increases.

Thus, the nuclear force of attraction on the 8 valence electrons of Neon will be the highest. And the nuclear force of attraction on the 5 valence elctrons of Nitrogen will be the lowest.

Since the nuclear charge and nuclear force of attraction in case of Nitrogen is the lowest, it is easy to remove Nitrogen's valence electrons. Thus, Nitrogen will have the lowest first ionization energy.

Hence , Option B is the correct answer.