Group 8: Iron Family

Group 8 includes Iron (Fe), Ruthenium (Ru), Osmium (Os) and the artificially produced Hassium (Hs). This latter was discovered in Darmstadt and named after the state of Hesse. They are all a silvery color and have the same outer shell electron configuration in elemental form. They’re all transition metals, and all of them are quite hard in relative terms. For instance, Iron has a great tensile strength and is ductile. This makes it an ideal metal for hard tasks (Griffith, 2010).

 

1. Electronic Configuration

General electronic configuration of group 8 is (n-1) ns2 nd6, while the electronic configuration of group 8 members is as follows (Kaji, et al., 2015).

 

Fe [26] 1s2 2s2 2p6 3s2 3p6 4s2 3d6 or [Ar] 4s2 3d6
Ru [44] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d7 or ⦏kr⦐ 5s14 d7
Os [76] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d6 or [Xe] 6s2 4f14 5d6
Hs [108] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14. 6d6 or [Rn] 7s2 5f14 6d6

 

2. Trend in the physical properties

They are malleable, hard, shiny, and have good conductivity. Groups 8 elements are distinguished by their high sublimation value. Certain substances seem sufficiently malleable, that may be carved using such just scalpel. However, most metals have a high boiling point. They are also very ductile. Their high melting points make them useful for conducting electricity. These metals may be shaped into a wide variety of forms due to their malleability. Moreover, it can withstand very hot conditions (Ishiguro, T. 2021).

 

2.1. Atomic and ionic radii

Ionic radii of of group 8 elements increase gradually from Fe4+ to Os4+ while atomic radii show irregular change from top to bottom. Ruthenium has larger atomic radius among its group members (Griffith, 2010).

Atomic radius group 5 periodic table

Figure 1: Atomic radius of Group 8 elements

Ionic radius group 5 periodic table

Figure 2: Ionic radius of Group 8 elements

 

2.2. Ionization energy

Ionization energy of group 8 elements show irregular change from iron to Hassium. Osmium has highest ionization energy among its group members (Kaji, et al., 2015).
Ionization energy of group 8 elements in kilo joule per mole

First ionization energy group 5 periodic table

Figure 3: First Ionization Energy of the Group 8 elements

 

2.3. Melting and boiling point

Melting and boiling point of group 8 elements increases from iron to Osmium while melting and boiling point of Hassium is unknown (Ishiguro, T. 2021).

melting and boiling points group 5 periodic table

Figure 4: Melting and Boiling Points of the Group 8 elements

 

3. Coordination chemistry of group 8

The coordination chemistry of group 8 includes some of the most interesting and colorful compounds, such as the dye Iron(II) phthalocyanine (dark purple, green or black), which is found in certain blue dyes and is also used in blue jeans. Important coordination complexes of group 8 elements are FeCl4 anion, [Fe(H2O)6]2+, Tris(bipyridine)ruthenium(II) chloride…etc (Griffith, 2010).

 

4. Uses of Group 8 elements

They are also used in alloys, which are important in our daily lives. These metals have been used in the production of ammonia from natural gas. These alloys have also been used to make wear resistant electrical contacts. For the purpose of creating durable power cables, Ruthenium is often combined alongside other members of the Platinum family metallic materials (Kaji, et al., 2015). It is also used in coloration of ceramics. Both the production of biological energy as well as the creation of new DNA depend on iron. Hemoglobin is a protein that is important for delivering oxygenation throughout the body. Hemoglobin also includes iron. Quite a few pharmaceuticals rely on Iron. It’s not only for the kitchen or the fields, though. Iron plays an important role in maintaining the proper growth of plants. Iron is also present in the human brain. It is handled by about twenty to thirty proteins (Ishiguro, T. 2021).

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Conclusion

During the early twentieth century, chemists were beginning to recognize a whole family of elements previously unknown. These elements were grouped together in a new periodic table. Originally, the elements were grouped into three separate groups. The group VIII was named in the old system. These elements were combined with the VIII B group and placed into one group. Among the group of elements in the Periodic Table, Group 8 comprises transition metals. These elements have high melting points and are hard, but their relative hardness depends on the number of valence electrons. They don’t have any flavor or hue either. Moreover, they are tough but pliable. They are primarily metalloids, but they can also form covalent bonds in compounds. These metals are often good conductors of electricity.

 

References

1. Griffith, W. P. (2010). The group VIII platinum-group metals and the Periodic Table. Foundations of Chemistry, 12(1), 17-25.
2. Kaji, M., Kragh, H., & Palló, G. (Eds.). (2015). Early responses to the periodic system. Oxford University Press, USA.
3. Maeno, Y., Hagino, K., & Ishiguro, T. (2021). Three related topics on the periodic tables of elements. Foundations of Chemistry, 23(2), 201-214.