Question

In manganese during ionization enthalpy why the electron had to be removed from 4s orbital first

Answer 1

In ionisation electrons are always removed from the outer most shell of the electron.

The electron configuration of Mn is 4s2 3d5, although the energy of both these shells is same, but the value of n is more for 4s orbital which means it will be more easy to remove to remove an electron from it.

Moreover, the electrons in d orbital also show the shieding effect and decrease the force of attraction between 4s orbital and nucleus thus it is easier to remove electrons from it.