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The elements in the first-half of the transitionseries exhibit many oxidation states with Mn exhibiting maximum number ofoxidation states (+2 to +7). The stability of +2 oxidation state increases withthe increase in atomic number. This happens as more electrons are gettingfilled in the d-orbital. However, Sc does not show +2 oxidationstate. Its electronic configuration is 4s2 3d1.It loses all the three electrons to form Sc3+. +3 oxidation state ofSc is very stable as by losing all three electrons, it attains stable noble gasconfiguration, [Ar]. Ti (+ 4) and V(+5) are very stable for the same reason.For Mn, +2 oxidation state is very stable as after losing two electrons,its d-orbital is exactly half-filled, [Ar] 3d5.