Question

The ground state electronic configuration of fe3+ ( z=26) is

Answer 1

Fe3+

1s2 2s2 2p6 3s2 3p6 3d5

Answer 2

In order to write the Iron electron configuration, we first need to know the number of electrons for the Fe atom (there are 26 electrons).

First write the electronic configuration of Fe which is :

                          Fe : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

Note that when writing the electron configuration for an atom like Fe, the 3d is usually written before the 4s. Both of the configurations have the correct numbers of electrons in each orbital, it is just a matter of how one prefers to write. Thus we can also write it as :

                         Fe : 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²

For the Fe³⁺ ion, we need to remove a total of three electrons (two from the 4s² and one from the 3d⁶ which gives us :

                      Fe³⁺ : 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s⁰

⇒ The ground state electronic configuration of fe3+ ( z=26) is

    Fe³⁺ : 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s⁰