The ionisation energy of H atom is `13.6 ` eV. What will be the ionisation energy of `He^(o+)` and `Li^(2+)` ions ?

Explanation

Ionisation energy =- (energy of the 1st orbit)
Energy of the 1st orbit of hydrogen `=- 13.6 eV`
Energy of the 1st orbit of `He^(+) =- 13.6 xx Z^(2)` (Z for `He^(+) = 2)`
`=- 13.6 xx eV=- 54.4eV` so, Ionisation energy of
`He^(+) =- (-54.4) = 54.4 eV`
Energy of 1st orbit of `Li^(2+) =- 13.6 xx 9 =- 122.4 eV`
Ionisation energy of `Li^(2+) =- (-122.4) = 122.4eV`