While reading d and f block elements from my book I got this line:
"The irregular trend in the first ionization enthalpy of the 3d metals can be accounted for considering that the removal of one electron alters the relative energies of 4s and 3d orbitals. So the unipositive ions have dn configurations with no 4s electrons. There is thus a REORGANISATION ENERGY accompanying ionisation with some gains in exchange energy as the number of electrons increases and from the transference of s electrons into d orbitals. "
The Attempt at a Solution
First of all, if any unipositive element has dn configuration then why would it have no electrons in its s orbital? (As the second line says)
And the third line, I didn't get anything of it... [/B]