Periodic table iron triad elements

Cobalt. The speciation of radiocobalt has been selected for discussion in this chapter because it exemplifies an element for which much information already exists regarding its stable chemical speciation, yet there are additional species which have become environmentally important as a result of the activities of the nuclear industry Cobalt, the middle member of the first triad of group VIII transition metals in the Periodic Table (iron, cobalt, nickel), is most stable in the divalent state when in simple compounds. Studies of radionuclide releases from nuclear power plants under tropical conditions in India seem to indicate that... 

The Grouping of Elements into Triads—Atomic Weights of the Elements— General Properties of tho Elements—Comparative Study of Iron, Cobalt, and Nickel—Their Position in tho Periodic Table—Comparative Study of Iron, Ruthenium, and Osmium—Comparative Study of Cobalt, Rhodium, and Iridium—Comparative Study of Nickel, Palladium, and Platinum. 

The elements Fe, Co and Ni, the triad in the middle of the periodic table, are similar from the chemical point of view but quite different in their influence on the environment and their significance for life. As described in Chapter 8 Iron, this element is tremendously important for human Hfe, as its atom is essential in hemoglobin and is thus responsible for oxygen uptake in the lungs. Cobalt, present in the form of vitamin Bj2, is necessary to prevent serious anemia. The role of nickel in mammals and humans is very Hmited and confined to its presence in one single enzyme, urease, which catalyzes the decomposition of urea to ammonia. Nickel was, however, very important in a very early epoch of life on earth. 

Periodic table. Locate the following classes of elements on Table 7.4, page 109 (a) the alkali metals, (b) the halogens, (c) the noble gases, (d) the alkaline earth metals, (e) the iron triad, (f) the rare earth elements, (g) the coinage metals. 

We place hydrogen as the first element in the first period, along with helium. When helium was discovered, Mendeleev put it in the second period. We put the triads of iron, cobalt, and nickel ruthenium, rhodium and palladium and osmium, iridium, and platinum in group VIIIB, in the middle of the table. Mendeleev put them in group VIII. We also have two long groups, the lanthanides and actinides, that were a headache for Mendeleev. 

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