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Difference Between Ferrous and Ferric

Main Difference

Iron (Fe) is the fourth abundant element found in Earth’s crust, and is also the most abundant element on Earth. Its multipurpose usage makes it even more important in human lives. In the periodic table, Iron is present in the ‘d Block’ and is one of the transition metals, which are the metals possessing multiple valencies. Transition metals can exist in several stable oxidation states. Iron being a transition metal also exhibits multiple valencies, which makes it stay stable in different oxidation states. Ferrous and Ferric are the two oxidation states of Iron, which form due to the difference in electronic configuration. Ferrous has +2 oxidation state, whereas ferric has +3 oxidation state. Actually, the oxidation state in both the Iron ions tells that ferrous needs to share two more electrons with oxygen to make the entire ion neutral, on the other hand, ferrous needs three electrons to make the ion neutral.

Comparison Chart

BasisFerrousFerric
Oxidation State+2 oxidation state+3 oxidation state
Electronic Configuration1s22s22p63s2 3p6 3d61s22s22p63s2 3p6 3d5
StabilityLessMore
Example of CompoundsFeO, FeCl2, FeSO4,Fe2O3, FeCl3, Fe2(SO4)3
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What is Ferrous?

Ferrous refers to the +2 oxidation state of the Iron element, and is denoted as Iron (II) or Fe2+. Apart from its usage in the field of chemistry, ferrous is also used an adjective that indicates about the presence of Iron in any material or compound. The electronic configuration actually differs ferrous from other stable ions of Iron. As mentioned above Iron is present in the ‘d Block’ of periodic table and is a transition metal, it has more mobility in its electrons and in order to have stability it gives away electrons and forms positive ions. The electronic configuration for the Iron element is 1s22s22p63s23p6 4s23d6. On the other hand, when it is about Ferrous ion, 3d orbitals possess higher energy than the 4S orbitals, despite this electrons are released from the 4s orbitals as it is the outermost orbital in this case. The electronic configuration for the Ferrous Iron is 1s22s22p63s2 3p6 3d6. The oxide of Ferrous is green in color and is the initial step in the formation of rust.

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What is Ferric?

Ferric refers to the +3 oxidation state of the Iron element, and is denoted as Iron (III) or Fe3+. When the Iron gets oxidized, it becomes the ferrous oxide, upon adding more oxygen, ferrous ion’s oxidation led to formation of the ferric ions. The Ferric Ion is seen as one of the most stabilized form of Iron ion, not only this, its electronic configuration is even more stable than the elemental form of Iron. When it is about neutralizing ferric ion requites to share three electrons with an oxygen molecule to make the ion neutral. The electron configuration of the ferric ion would be 1s22s22p63s2 3p6 3d5. The Ferric Iron is formed with removal of three electrons from iron, two of the electrons from 3s orbit are removed and one d-electron is removed in this case.

Ferrous vs. Ferric

  • Ferrous has +2 oxidation state, whereas ferric has +3 oxidation state.
  • The electronic configuration for the Ferrous Iron is 1s22s22p63s2 3p6 3d6,whereas the electron configuration of the Ferric Iron would be 1s22s22p63s2 3p6 3d5.
  • The Ferric Ion is more stable than the Ferrous Ion.
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Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss