A lithium atom has three 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 electronmove in the field of a totalcharge`+5a- 2a= +e`Thus the energies are the same as that if hydrogen atoms The lowest energy is
`E_(2) =(E_(1))/(4) = (-13.6ev)/(4) = -3.4eV`
Thus, the ionitation energy of the atom in this picture is `3.4eV`