How much energy is required to ionise a H - atom if the electron occupie ` n=5 ` orbit ? Compare your answer with the ionization energy of H-atom (energy required to remove the electron from ` nth` orbit ).

Answer

`8.72 xx 10^(-20) J, 2.18 xx 10^(-18) J`

Explanation

`E_n = -(2.18 xx 10^(-18))/(n^2) J "atom"^(-1)`
For ionization from 5th orbit,
`n_1 = 5 and n_2 = oo`
`=2.18 xx 10^(-18) (1/(n_1^2) - 1/(n_2^2))`
`= 2.18 xx 10^(-18) (1/(5^2) - 1/(oo)) = 8.72 xx 10^(-20) J`.
For ionization of H atom,
`n_1 = 1, n_2 = oo`
`Delta E = 2.18 xx 10^(-18) (1/(1^2) - 1/(oo))`
`= 2.18 xx 10^(-18)J`