Manganese and Iron in the Transition Metal Series: Unpaired Electrons and 2 Ions

The transition metal series Sc through Zn consists of a variety of elements with complex electronic structures. Among these elements, manganese (Mn) and iron (Fe) are notable for their unique 2 oxidation states, characterized by four unpaired electrons. This article explores the electronic configurations of these elements and their significance in the larger context of the transition metal series.

Understanding the 2 Oxidation States of Manganese and Iron

The 2 oxidation state of manganese and iron is particularly interesting due to their electronic configurations and the distribution of their unpaired electrons. Manganese is part of the transition metals, where its common oxidation states include 2, 3, and 4.

Manganese (Mn)

In its 2 oxidation state, manganese has the following electron configuration:

[Ar] 3d5

This configuration results in five unpaired electrons, not four. Hence, manganese does not fit the criteria of having four unpaired electrons in its 2 state. This is an important detail to highlight, as it shows the complexity and exceptionality of transition metals.

Iron (Fe)

Iron, on the other hand, in its 2 oxidation state, has the following electron configuration:

[Ar] 3d6

In this state, iron has four unpaired electrons, which makes it a significant element in the transition metal series.

Commonality in Transition Metals

Even despite this discrepancy, both manganese and iron share a commonality with other transition metals in their series (Sc through Zn). These elements typically have a relatively small energy difference between the 4s and 3d orbitals, which allows them to form ions of different charges.

Electron Configuration and Ion Formation in Transition Metals

When transition metals form ions, the 4s electrons are lost first, followed by the 3d electrons if needed. For example, in the case of iron (Fe) and chromium, both elements tend to remove their 4s electrons first to form a 2 ion.

Chromium (Cr)

Chromium neutral element has 5 electrons in the 3d orbitals and 1 electron in the 4s orbital. Following Hund's rule, these 5 electrons are distributed over the 5 suborbitals with one electron in each. To form a 2 ion, it will give up the 4s electron and one 3d electron, leaving 4 unpaired 3d electrons in its ion.

Iron (Fe)

Iron neutral element has 6 electrons in its 3d orbitals and 2 electrons in its 4s orbital. To form a 2 ion, it will give up both 4s electrons, leaving all 6 3d electrons, 4 of which are unpaired.

Unpaired Electrons Formula for Yourself

When working on your own, to determine the number of unpaired electrons in a 2 ion: Identify the number of electrons in the outermost 4s and 3d orbitals. For the 2 ion, remove two electrons starting with the 4s orbital first. The remaining electrons in the 3d orbital will show you the number of unpaired electrons.

This method applies to any element in the transition metal series, including manganese and iron, allowing you to determine their unpaired electron configurations accurately.