Group VIA Oxygen and the Sulfur Family

Such lakes become oxygen-deficient from decomposing plants and algae, and the fish die. In the United States, the use of phosphates in laundry detergents has been banned in some states. 

Group VIA, like the preceding groups, shows the trend from nonmetallic to metallic as you proceed from top to bottom of the column of elements. Oxygen and sulfur are strictiy nonmetallic. Although the chemical properties of selenium and tellurium are predominantly those of nonmetals, they do have semiconducting allotropes as expected of metalloids. Polonium is a radioactive metal. 

Ozone and its presence in the atmosphere are discussed in an essay at the end of Chapter 10. 

Oxygen is produced in enormous quantity from air. As described in the discussion of nitrogen, air is first liquefied, then distilled. Nitrogen and argon are more volatile components of air and distill off, leaving hquid oxygen behind. 

Oxygen can be prepared in small quantities by decomposing certain oxygen-containing compounds. Both the Swedish chemist Karl Wilhehn Scheele and the British chemist Joseph Priestley are credited with the discovery of oxygen. Priestley obtained the gas in 1774 by heating mercury(II) oxide. 

---

Polonium is the heaviest element in the chalcogen family. It is in Group 16 (VIA) in the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. The other chalcogen elements are oxygen, sulfur, selenium, and tellurium. 

---