Question

The element with highest ionization potential is:
(A) \[Na\]
(B) \[Ar\]
(C) \[Cl\]
(D) \[P\]

Answer 1

Hint: To find out the ionization energy we should know what it means. We know that different atoms have different ionization energy based on the attraction of the electron towards the nucleus and the orbital in which it is present.

Step by step answer:Ionization is defined as the process of removing an electron from an isolated atom to form a positive ion.
First ionization energy: The amount of energy required to remove the outer electrons in valence shell electrons from an isolated gaseous atom to form a cation.
Second ionization energy: The amount of energy required to remove the second electron from the gaseous mono-positive cation in gaseous state to form a dipositive cation, which is removed after the first electron is called second ionization potential.
Factors which affect the magnitude of ionization potential are:
-Effective nuclear charge
-Atomic size i.e. atomic radius
-Principle quantum number
-Shielding effect
-Half-filled and completely filled orbitals
-Nature of orbitals
-The extent of penetration of valence electron
Trend in the periodic table:
Tends increase across the period: As radius decreases across the period, the electron you are removing is closer to the nucleus and it is harder to remove.
Tends to decrease down the group: Outer electrons are easier to remove as they are far from the nucleus.
In the given options the number of electrons of argon is eighteen and hence it is completely fill and stable noble gas element it will require highest energy to remove the electron as it satisfies octet rule for stability, and the I1 increases as we move from left to right because electrons are filled in the same orbital and it remains closer to the nucleus. Hence, the energy required to remove an electron is maximum.

Therefore, the answer is (B) \[Ar\].

Note: Ionization potential energy is different from excitation, the electron gets energy to jump from ground state to the excited or valence state. It won’t stay in the excited state for too long it will come back into its original state after emitting the absorbed energy.