## Chemistry: Molecular Approach (4th Edition)

The $4s$ electrons are easily lost during the formation of the $~+2$ state.
The $+2$ state is very common for transition metals because the $4s$ electrons are easily lost during the formation of the $~+2$ state, as removal of electrons from the d orbitals is difficult as compared to the s orbitals. Example: $Mn:\quad \left[ Ar \right]3{{d}^{5}}4{{s}^{2}}$ In the above example, the d orbital is half-filled, due to which it requires more energy as compared to the s orbital to release electrons. So, the s orbital easily releases electrons to form the +2 state.