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