Question

What is ionization potential. Explain the factors which affect ionization potential.

Answer 1

Hint: Ionization energy repents the ease with which an atom can lose electrons. Any factor that increases the attraction between the nucleus and the outermost electron, also increases the ionization energy.
Complete step by step answer:
Ionization potential represents the amount of energy needed to remove an electron from the valence shell of an isolated gaseous atom. The valence shell is the outermost shell. When a neutral atom loses an electron, it forms mono positive cation. The amount of energy needed to remove this electron is the first ionization energy. When the monopositive cation loses another electron, the energy needed is second ionization energy.
Thus consider an isolated gaseous magnesium atom.
It loses one electron to form mono positive cation. When the second electron is lost, dipositive cation is obtained.
\[{\text{Mg }} \to {\text{ M}}{{\text{g}}^ + }{\text{ + }}{{\text{e}}^ - }{\text{ first ionization energy }} \\
{\text{M}}{{\text{g}}^ + }{\text{ }} \to {\text{ M}}{{\text{g}}^{2 + }}{\text{ + }}{{\text{e}}^ - }{\text{ second ionization energy }} \\\]
Write down the factors affecting the ionization potential
A ) Atomic radii: With increase in the atomic radius, the attraction between the nucleus and the outermost electron decreases. Due to this, the outermost electron is loosely held. Due to this, less energy is required to remove the electron. Hence, with increase in the atomic radii, the ionization potential decreases.
B ) Effective nuclear charge: With increase in the effective nuclear charge, the attraction between the nucleus and the outermost electron increases. Due to this, the outermost electron is tightly held. Due to this, more energy is required to remove the electron. Hence, with increase in the effective nuclear charge, the ionization potential increases.
C ) Shielding effect: With increase in the shielding effect, the attraction between the nucleus and the outermost electron decreases. Due to this, the outermost electron is loosely held. Due to this, less energy is required to remove the electron. Hence, with increase in the atomic radii, the ionization potential decreases.
D ) Penetrating effect: Penetrating effect represents the ability with which the orbital attracts an electron. With increase in the penetrating effect, the ionization energy increases.
Stability of half filled and completely filled orbitals: Half filled and completely filled orbitals have extra stability. This extra stability increases the ionization energy.

Note: When an electron is removed from an atom, energy is needed. When an electron is added to an atom, energy is required. Usually, alkali metals and alkaline earth metals have very low first and second ionization energies respectively.