Group 8

Group 8 is a vertical column of the periodic table of chemical elements. It contains iron (Fe), ruthenium (Ru), osmium (Os), and hassium (Hs). All are transition metals, meaning their electrons occupy d-orbitals.

Group 8 is part of groups 8, 9, and 10, sometimes called the iron group or, when including Ru, Rh, Pd and Os, Ir, Pt, the light and heavy platinum metals. In the older European naming system, these three groups were designated VIII, a designation still seen in older publications.

Elements in the group

Iron (atomic number 26) is the most widely used element and the basis of steel and alloys. Ruthenium (44) and osmium (76) are rare metals in the platinum group; both have very high melting points, and osmium is among the densest known substances. Hassium (108) is a synthetic element with extremely short half-life, produced only in particle accelerators; its brief decay time makes it unusable for commercial purposes.

Chemical properties

Group 8 elements display variable oxidation states. Iron typically exhibits +2 and +3, while Ru and Os can reach much higher states up to +8, as in RuO₄ and OsO₄. As a result, unlike the elements in groups to the left, the horizontal similarity in this group is incomplete: iron differs from Ru and Os in corrosion resistance and high oxidation chemistry.

Applications

Iron is used in construction, vehicles, and manufacturing, and plays a role in living organisms, notably in hemoglobin for oxygen transport. Ruthenium is used in chemical catalysts and electronic components. Osmium is alloyed into very hard materials, such as instrument needle tips, and osmium tetroxide is used for staining biological tissues.