# How Much Energy is Required to Ionise a H Atom If the Electron Occupies N = 5 Orbit? Compare Your Answer with the Ionization Enthalpy of H Atom (Energy Required to Remove the Electron from N =1 Orbit). - Chemistry

How much energy is required to ionise an H atom if the electron occupies n = 5 orbit? Compare your answer with the ionization enthalpy of H atom (energy required to remove the electron from n =1 orbit).

#### Solution

The expression of energy is given by,

E_n = (-(2.18xx10^(-18))Z^2)/n^2

Where,

Z = atomic number of the atom

n = principal quantum number

For ionization from n1 = 5 to n_2 = oo

triangleE = E_(oo) -  E_5

=[{{-(2.18xx10^(-18)J)(1)^2)/(oo)^2}-{(-(2.18xx10^(-18)J(1)^2))/(5)^2}]

= (2.18xx10^(-18)J)(1/((5)^2))       (Since 1/oo = 0)

= 0.0872 xx 10^(-18) J

triangle E = 8.72 xx 10^(-20) J

Hence, the energy required for ionization from n = 5 to n = oo is 8.72 × 10–20 J.

Energy required for n1 = 1 to n = oo

triangleE' = E_(oo) - E_1

= [{(-(2.18xx10^(-18))(1)^2)/(oo)^2}-{(-(2.18xx10^(-18))(1)^2)/(1)^2}]

= (2.18 xx 10^(-18)) [1 - 0]

= 2.18 xx 10^(-18) J

Hence, less energy is required to ionize an electron in the 5th orbital of hydrogen atom as compared to that in the ground state.

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#### APPEARS IN

NCERT Class 11 Chemistry Textbook
Chapter 2 Structure of Atom
Q 14 | Page 66