Group 9 element 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 in chemical behavior; however, rhodium deviates from the pattern.
Cobalt sulfide Cobalt sulfide Cobalt sulfide is the name for chemical compounds with a formula CoS. Well-characterized species include minerals with the formula CoS, CoS, CoS, and CoS. In general, the sulfides of cobalt are black, semiconducting, insoluble in water, and nonstoichiometric. Cobalt sulfides occur widely as minerals, comprising major sources of all cobalt compounds. Binary cobalt sulfide minerals include the cattierite (CoS) and linnaeite (CoS). CoS (see image in table) is isostructural with iron pyrite, featuring disulfide groups, i.e. CoS. Linnaeite, also rare, adopts the spinel motif. The CoS compound is known as a very rare cobaltpentlandite (the Co analogue of