Sulfur, Selenium, Tellurium, and Polonium

Sulfur, selenium, tellurium and polonium constitute the heavier elements of group VIB of the periodic table and are sometimes referred to as the chalcogens, chalcogenins, chalcogenides or chalconides. Developments in the understanding and interest in the chemistry of these elements have been reviewed at appropriate intervals during the past 20 years.1-8... 

Sulfur, Selenium, Tellurium and Polonium Table 1 Compounds of Group VI Elements and their Stereochemistries... 

The group 6A elements are oxygen, sulfur, selenium, tellurium, and polonium. As shown in Table 19.7, their properties exhibit the usual periodic trends. Both oxygen and sulfur are typical nonmetals. Selenium and tellurium are primarily non-metallic in character, though the most stable allotrope of selenium, gray selenium, is a lustrous semiconducting solid. Tellurium is also a semiconductor and is usually classified as a semimetal. Polonium, a radioactive element that occurs in trace amounts in uranium ores, is a silvery white metal. 

Compare the stracmres of the dioxides of sulfur, selenium, tellurium, and polonium. How do they relate to the metallic or nonmetallic character of these elements ... 

The group 16 elements - oxygen, sulfur, selenium, tellurium and polonium - are called the chalcogens. 

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