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Why the third ionisation enthalpy of Mn is generally exceptionally high?

bcoj when Mn+2  oxidises to Mn+3.before oxidation it hav 3d5 4s0 ,it gains half filled configuration   but after oxidation in Mn+3 state ,1 more electron have to be released so it releases from half filled configuration which is stable .so to remove third electon  it results high ionisation enthalpy.

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Hi,

 

The electronic configuration of manganese is -1s2, 2s2, 2p6, 3s2, 3p6, 3d5 4s2

 

When electrons are removed from the manganese atom, the first two electrons are removed with ease since it left the manganese ion with half filled d orbitals i.e. with five unpaired electrons. The half filled orbital imparts stability to the manganese ion due to greater exchange energy. Thus it does not prefer to lose one electron which disturbs its stability and hence not favorable from energy point of view.

 

Hope it clears.

Cheers!

@richudwivedi:very good answer.keep it up!thumbs up!

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