Question

Iron and Cooper have dual valency but according to the electron configaratcon Iron should have a valenxv of 2 then why is there a second valency?

Answer 1

Valency definition :it is the measure of combining power with other elements.

So, iron having atomic number 26. It has two electrons in its 4s orbital and 6 electrons in its 4d orbital.

In order to attain stability it looses it two electrons in the 4s orbital and hence have +2 valency and since the half filled orbitals are more stable it loses one more electron from d orbital and has +3 valency.


When iron has +2 valency it has actually lost its 4s electrons but when it has avalencyof +3 ,it has lost 4s electrons along with one electron from the paired electrons in 3d orbital , thereby leaving unpaired electrons in each of the five 3d orbitals , this is because partially filled d orbitals have extra stability…