Question

What is the difference between \[F{e^{2 + }}\] and \[F{e^{3 + }}\]?

Answer 1

Hint: We know that Iron (Fe) is in the d-block of the periodic table. The atomic number is 26 which means that there are 26 electrons in the Iron atom. It can be represented by the following electronic configuration.
\[1{s^2}\;2{s^2}\;2{p^6}\;3{s^2}\;3{p^6}\;4{s^2}\;3{d^6}\]
Now we have two get \[F{e^{2 + }}\] and \[F{e^{3 + }}\] by removing electrons from this
For \[F{e^{2 + }}\] we have to remove 2 electrons from the \[4s\] orbital and for \[F{e^{3 + }}\]we have to remove 2 electrons from the \[4s\] orbital and 1 electron from the \[3d\] orbital.
This is one of the key factor that gives the different properties for \[F{e^{2 + }}\] and \[F{e^{3 + }}\]

Complete answer:

	\[F{e^{2 + }}\]	\[F{e^{3 + }}\]
General characters	Fe loses 2 electrons from the valence shell and becomes \[F{e^{2 + }}\] (+2 oxidation state)	Fe loses 3 electrons from the valence shell and becomes \[F{e^{3 + }}\](+3 oxidation state)
Name	It is known as the ferrous ion	It is known as the ferric ion
Colour	Ferrous ions produce green colour in solutions and turns violet when added to waterE.g. \[FeS{O_4}.{\text{ }}7{H_2}O\]	Ferric ions produce yellow-brown colour in solutionE.g. \[FeC{l_3}.{\text{ 6}}{H_2}O\]
Magnetism	Usually, paramagnetic.  However because there are an even number of electrons in Fe2+, it is possible that all of the electrons could end up as diamagnetic (low-spin complexes)	They can only be paramagnetic because there is always a lone electron
Electronic Configuration	\[1{s^2}\;2{s^2}\;2{p^6}\;3{s^2}\;3{p^6}\;3{d^6}\]	\[1{s^2}\;2{s^2}\;2{p^6}\;3{s^2}\;3{p^6}\;3{d^5}\]
Stability	\[F{e^{2 + }}\] is not stable.	\[F{e^{3 + }}\] ion is more stable due to its half-filled \[3{d^5}\] electron configuration

Note:
Both \[F{e^{2 + }}\] and \[F{e^{3 + }}\] are the common oxidation states of Iron.
Ferrous Ion when kept for a long time can oxidise and therefore turn into ferric ions changing the colour and other properties.
Ferrous state (\[F{e^{2 + }}\]) iron acts as an electron donor, while in the ferric state (\[F{e^{3 + }}\]) it acts as an acceptor. They play important roles in our biological system like haemoglobin.