<span>
It makes sense that an inner shell electron would be tougher to remove
than a valence electron because the inner shell electron is closer to
the positive nucleus of the atom. Seeing as an electron caries a
negative charge it would be too attracted to the positive core to leave
readily. Also, the inner shell electrons are constantly repelling
electrons outside of it's energy level (however the reason these
electrons outside innershell energy levels don't simply fly away is the
charge of the positive core overcomes the smaller charges of the
comparably negligible inner shell electrons, but that repulsion is still
there so keep that in mind) </span>
