Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
seo-qna
SearchIcon
banner

Explain why: Mn+2 is more stable than Fe+2 towards oxidation state to +3 state.(At. No. of Mn=25, Fe=26)

Answer
VerifiedVerified
499.5k+ views
like imagedislike image
Hint: Fully filled and Half filled electronic configurations are more stable. Oxidation states with stable configurations are more easy to obtain than oxidation states with relatively less stable electron configurations.

Complete answer:
Manganese has atomic number 25, and electronic configuration of manganese is 1s2,2s2,2p6,3s2,3p6,4s2,3d5.
On removal of two electrons,it becomes Mn+2, whose configuration is [Ar]4s0,3d5.
As we can see that on removal of two electrons, manganese have a configuration where d-block is half filled. We know that half filled and fully filled orbitals are more stable than any other configuration. Therefore, Mn+2 is stable at this oxidation state.
Iron has atomic number 26, and electronic configuration of Iron is 1s2,2s2,2p6,3s2,3p6,4s2,3d6.
On removal of two electrons, it becomes Fe+2, whose configuration is [Ar]4s0,3d6.
Now Iron has six electrons in d-orbital, making the d-orbital unsymmetrically filled. So to obtain symmetry and more stability it will lose one more electron to go on to +3 oxidation state.
After losing one more electron from Fe+2, it becomes, Fe+3, whose configuration is [Ar]4s0,3d5.
Now we see, in Fe+3, d-orbital is half filled with d5configuration. It is more stable than d6 configuration in Fe+2.
Now, when we compare, manganese and iron, we see that manganese has half filled d-orbital in +2 oxidation state which is more stable than any other oxidation state of manganese, and iron have half filled d-orbital in +3 oxidation state, therefore, iron tends to move toward +3 oxidation state and Manganese is stable at +2 oxidation state.

Note: The reason for the stability of half filled and fully filled orbitals or configurations is because of symmetry and exchange energy. The half filled and fully-filled orbitals are more symmetrical than any other configurations and symmetry leads to more stability. Also electrons present in different subshells exchange their positions, when electrons are filled symmetrically, exchange energy is less, hence greater stability.