Question

The element with the highest ionization potential is:
A) Nitrogen
(B) Oxygen
(C) Helium
(D) Neon

Answer 1

Ionization potential depends on the size of the atom and nuclear charge. If we move along a period in the periodic table the ionization potential increases and along with a group it decreases. Thus, the elements which will be on the extreme right side of the periodic table (noble gases) will be having the highest ionization energy. Therefore, our answer will be a noble gas.

Complete step by step solution:
-Ionization potential is often referred to as ionization energy also. Let's start with the concept of Ionization potential. It can be described as the amount of energy required to remove an electron from the outermost shell of an ion or atom by breaking the bond. It is usually measured in Kilojoule per mole.
-Or in other words, it is the measure of the strength of attractive forces by which an electron is held in a place. The ionization energy of an element depends on its position in the periodic table because the attraction between electrons and the nucleus plays an important role in determining the ionization potential.
-When we move down in a group in the periodic table, the attraction between electrons and nucleus decreases as new shells are getting added and hence it’s easier to remove an electron from an atom or ion. Thus, ionization potential decreases along with a group.
-When we move from left to right across the periodic table that is from an alkali-metal atom to a noble gas, the n value of the outermost electrons remains the same, but the nuclear charge increases steadily and this increased nuclear attraction requires more energy to remove an electron and as a result of the ionization potential increases along a period.
-So, from the above discussion, it's clear that inert gases or noble gases will have the highest ionization potential since they are present at the end of each period.
-Among the given options Helium and Neon are inert gases and among them, Helium will have the highest ionization potential as it has the smaller size and higher attraction between nucleus and electrons.

Therefore, the answer is option (C) Helium.

Note: It should be noted that the general trend of ionization potential in the periodic table has some exceptions. The first exception is in between boron and beryllium. Here Boron has a lower value than beryllium due to the presence of p subshell. The second exception is the lower value of oxygen than nitrogen due to the half-filled orbitals in nitrogen.