How to Identify Fe(iron) valency? How to know where we should use +2 or +3 valency


Valency +2 for Iron(II)
Valency +3 for Iron(III)
Iron has atomic number 26 and it's electronic configuration is 
1s2 2s2 2p6 3s2 3p6 3d6 4s2 
The energy of 4s and 3d orbital is similar (4s has slightly higher energy). Also, 3d orbital has 1 electron pair, rest of the electrons are unpaired.

Now, when iron loses the two of its 4s electrons, it attains a valency of +2.
Sometimes, iron will also lose one of the paired electrons from 3d orbital, leaving the entire 3d orbital filled with unpaired electrons (which provides a more stable configuration). In this case, its valency will be +3.

So it depends on the reaction, reagents, temperature conditions, requirement for the Valency of Iron or to the ion it is sharing it's electron with. 

  • 0
What are you looking for?