Solved Example on Ionization Energy
Example 1: Calculate the ionization energy of the Hydrogen atom if the electron is in the second orbit.
Solution:
For hydrogen given, Z = 1, n = 2
Thus,
ΔE = 13.6 × n2 / Z2
= 13.6 × 1/4
= 3.4 eV
Example 2: Find the IE required to remove the outermost electron from the Sodium atom.
Solution:
For Sodium, Z=11 and n=3 for outermost electron
Thus,
ΔE = 13.6 × n2 / Z2
= 13.6 × 121/9
= 182.844 eV
Example 3: Calculate the wavelength of radiation required to ionize the Na atom if it is known that the ionization energy of Na is 496 kJ/mol.
Solution:
Given,
ΔE = 496 kJ/mol,
λ = ?
We know that E = hc / λ
496 = (6.6 × 10−34 × 3 × 108) / λ
λ = 3.99 ×10−28 ms−1
Example 4: The first, second, and third ionization energies of Aluminium are 578, 1817, and 2745 kJ/mol. Calculate the ionization energy required to convert Al ion to Al3+.
Given,
ΔH1 = 578, ΔH2 = 1817, ΔH3 = 2745
Al + ΔE ⟶ Al3+
ΔE = ΔH1 + ΔH2 + ΔH3
ΔE = 578+1817+2745
= 5140 kJ/mol
Ionization Energy
Ionization energy can be defined as the minimum amount of energy required to remove the valence electron i.e. the most loosely bound electron from an isolated gaseous atom or ion. It is important to note the term isolated gaseous atom as if the atom is not isolated, then the energy required may be more due to the interatomic forces.
Let’s learn about Ionization Energy in detail in this article.