Question

The binding energy of an electron in the ground state of He atom is equal to `E_0 = 24.6 eV.` Find the energy required to remove both electrons form the atom.

Answer 1

To remove one elctron requires `24.6eV`
The ion that is left is `He^(+)` which in its ground stat has a binding energy of `4E_(H)=4 ħR`.
The complete binding energy of both electrons is then
`E=E_(0)+4 ħR`
Substitution gives `E=79.1eV`