Group 9 element Rhodium, iridium, and meitnerium have no known biological roles. Group 9 element Group 9, numbered by IUPAC nomenclature, is a group of chemical element in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and perhaps also the chemically uncharacterized meitnerium (Mt). These are all transition metals in the d-block. All known isotopes of meitnerium are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends
Cobalt-60 intensity gamma-ray emitter with a relatively long half-life, 5.27 years, compared to other gamma ray sources of similar intensity. The β-decay energy is low and easily shielded; however, the gamma-ray emission lines have energies around 1.3 MeV, and are highly penetrating. The main uses for are: Cobalt has been discussed as a "salting" element to add to nuclear weapons, to produce a cobalt bomb, an extremely "dirty" weapon which would contaminate large areas with nuclear fallout, rendering them uninhabitable. In one hypothetical design, the tamper of the weapon would be made of . When the bomb exploded, the excess neutrons