Following an earlier article on the positions of lanthanium and lutetium in the periodic table (J. Chem. Educ.1982,59, 634-636), the author notes that introductory textbooks, inorganic textbooks, and advanced monographs on coordination and organometallic chemistry are increasingly treating zinc, cadmium, and mercury as transition or d-block elements, rather than as main-block elements. The author reviews the historical evolution of the concepts of transition elements and d-block elements, evaluates the chemical and spectrosopic evidence for each placement, and concludes that these elements are unambiguously main-block elements and that there is a fundamental bifurcation of group 2 at magnesium into a Ca–Ra branch and a Zn–Hg branch. The author also reviews various ways of representing this bifurcation using spatial position in the periodic table and various labeling schemes.
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Citation
Jensen, William B. J. Chem. Educ.2003 80 952.
Keywords
Cadmium; General Chemistry; History / Philosophy; Inorganic Chemistry; Mercury; Periodicity / Periodic Table; Textbooks; Zinc
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