- published: 30 Nov 2015
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In chemistry and physics, the iron group refers to elements that are in some way related to iron. These elements are relatively abundant both on Earth and elsewhere in the universe. The term is ambiguous in different contexts, and almost obsolete in chemistry.
The iron group in the periodic table referred to the elements iron, cobalt and nickel, that is the first row of group VIII (or VIIIB) under the old numbering system. These metals, and the platinum group immediately below them, were set aside from the other elements as they show obvious similarities among themselves in their chemistry, but are not obviously related to any of the other groups.
The similarities in chemistry along what is now known as the first row of the transition metals were noted by Adolph Strecker in 1859.Newlands' "octaves" (1865) were harshly criticized for separating iron from cobalt and nickel.Mendeleev stressed that groups of "chemically analogous elements" could have similar atomic weights as well as atomic weights which increase by equal increments, both in his original 1869 paper and his 1889 Faraday Lecture.