A lithium atom has electrons. Assume the following simple picture of the atom Two electron moves close to the nucleus making up a spherical cloud it and the third moves outside the cloud in a circular orbit . Bohr's model can be used for the motion of this third electron but` n = 1` state are not available to it. Calculate the ionization energy of lithium in ground state using the above picture.

Explanation

In this picture, the third electron moves in the field or a toal charge `+3e-2e+e`. Thus, the enrgies are the same as that of hydrogen atoms. The lowest energy is:
`E_(2)=(E_(1))/(4)= (-13.6eV)/(4)=3.4 eV`
Thus, the ionization energy of the atom in this picutre is `3.4 eV`.