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

Explanation

`E_(n)=-(21.76xx10^(-19))/(n^(2))J,E_(1)=-21.76xx10^(-19)J`,
`E_(5)=-(21.76xx10^(-19))/((5)^(2))=-8.704xx10^(-20)J and E_(oo)=0`
Energy requried for ionisation of ann electron from 5th orbit, `DeltaE=E_(00)-E_(5)=0-(-8.704xx10^(-20)J)=8.704xx10^(-20)J`
energy required for ionisation of an electron from 1st orbit, `DeltaE'=E_(oo)-E_(1)=0-(-21.76xx10^(-19)J)=21.76xx10^(-19)J`
`therefore (DeltaE)/(DeltaE')=(8.704xx10^(-20)J)/(21.76xx10^(-19)J)=4xx10^(-2)`