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

Explanation

In the present case, ionisation would involve the transfer of electron from n = 5 shell to `n =oo` shell.
`E_(5)=-(2.178 xx 10^(-18))/((5)^2)=-8.712 xx 10^(-20)"J atom"^(-1)`
and `E_(oo)=-(2.1798 xx 10^(-18))/((oo)^2)="0 J atom"^(-1)`
Hence the energy required for ionisation,
`triangleE=E_(oo) -E_(5)=0 -(-8.712 xx 10^(-20))`
`=8.712 xx 10^(-20)" J atom"^(-1)`
Ionisation enthalpy of H atom `=E_(oo)-E_(1)=triangleE.`
`=0(-(2.178 xx 10^(-18))/(1^2))`
`=2.178 xx 10^(-18) "J atom"^(-1)`
`(triangleE.)/(triangleE)=(2.178 xx 10^(-18))/(8.712 xx 10^(-20))=25`
Hence the ionisation enthalpy (energy required to remove electron from n=1 orbit) is 25 times the energy required to remove electron from n=5 orbit.