(5-19)  ① Again, we can make use of our energy expression, equation V-17:

The values you need to put in here are:

e = 1.602 x 10-19 C                               ε0 =  8.85 x 10-12 C2N-1m-2

 electron mass = 9.109 x 10-31 kg            Planck’s constant, h = 6.626 x 10-34 m2kgs-1

The radius of a proton (eg a 1H nucleus) is about 8.8 x 10-16 m. Use the equation to calculate the energy required to move an electron from its normal mean distance (as calculated in Question 5-16) to bring it to the edge of the nucleus.

②  Convert your answer to either eV or kJmol-1, according to your taste, and compare your answer with the ionisation energy you estimated in Question 5-17.