Why is the first ionization energy of boron LESS than that of beryllium? Boron has a higher atomic number.

1 Answer
May 13, 2016

Answer:

Consider electronic configurations of #Be# versus #B#. Should a #p# electron be easier to remove?

Explanation:

#Be, Z=4, 1s^(2)2s^2.#

#B, Z=5, 1s^(2)2s^(2)2p^1.#

A priori , should it be easier to remove a #p-#orbital electron, which by definition has zero electron density at the nucleus? An #s-#orbital electron, even those of the #2s# shell has some probability density at or near the nucleus, and this probably accounts for the differential ionization energies.