Question

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).

Answer 1

The expression of energy is given by,

Where,

Z = atomic number of the atom

n = principal quantum number

For ionization from n1 = 5 to  

,

Therefore ΔE = E2- E1 = - 21.8 X10-19 (1/n22-1/n12)

= 21.8 X10-19(1/n22-1/n12)

= 21.8 X10-19 (1/52-1/∞)

= 8.72 x 10-20 J

For ionization from 1st orbit, n1= 1,  

Therefore ΔE’ = 21.8x10-19(1/12-1/∞)

= 21.8x10-19 J

Now ΔE’/ ΔE = 21.8x10-19 / 8.72x10-20 = 25

Thus the energy required to remove electron from 1st orbit is 25 times than the required to electron from 5th orbit.

Answer 2

Answer:

25

Explanation:

The ratio of the ionization energy of electron in first orbit to the ionization energy of electron in fifth orbit is:

ΔEΔE′=8. 72×10−2021. 8×10−19

         =   25.