(5-19)  ①  The energy of the electron is given by equation V-17:

Substituting in the values of the constants, this becomes:

                          E  =  - (2.31 x 10-28)/<r>  +  (4.58 x 10-39)/<r>2

So, we get:

<r>                                                                               E/J            

4.0 x 10-11m (normal mean distance)                         -2.9 x 10-18

8.8 x 10-16m (radius of proton)                             +5.9 x 10-9

The energy needed to bring the electron in to the edge of the nucleus is therefore the difference between these energies, which is 5.9 x 10-9 J.

②  This equates to 3.7 x 1010 eV or, if you prefer, 3.6 x 1012 kJmol-1.  This compares to our estimated 18 eV / 1700 kJmol-1 for the ionisation energy. A whole different league.