Question

The energy required to remove both electrons from the Helium from its ground state is 79eV. Ho much energy is required to ionize Helium(remove one electron)?

Answer 1

The energy required to remove one electron from the ground state of $He^+$ (Hydrogen like atom )atom is

$E_n=\frac{13.6 Z^2}{n^2}$ eV

For ground state $n=1$ ,

$E_1=\frac{13.6 (2)^2}{1^2}=54.4 eV$

Given that the energy required to remove both electrons from the Helium from its ground state is $79eV$ .

So the energy required to ionize Helium is

= $79 eV -54.4 eV=24.6 eV$