Iron Group: Elements of the Eighth Subgroup

The elements of the eighth subgroup (iron, ruthenium, osmium, and hassium) are physically and chemically relatively similar to each other. The lanthanide contraction also affects ruthenium and osmium. In their physical properties, the platinum metals ruthenium and osmium differ quite significantly, but only slightly in terms of their chemical properties. Iron, on the other hand, deviates significantly from ruthenium, osmium, and probably also hassium in terms of its base character and its lower densities, melting and boiling points. The elements of this group can give up a maximum of eight outer valence electrons (two s- and six d-electrons each) to achieve a stable electron configuration. For iron, the oxidation state +3 is the most stable, for ruthenium +4, for osmium and hassium +8. The discovery of iron took place as early as 3000 BC in Mesopotamia, whereas osmium and ruthenium have been found in the first half of the 19th century. The first production of hassium atoms was successful in 1984.