1. Group 16 Elements By Zach Bindell, Val Chin, & Kevin Pugh

2. Chalcogens ●Each element contains six valence electrons ●Each element forms 2- ions ●Located in the p block of the periodic table ●The term chalcogen was first used by the Wilhelm Blitz research group at the University of Hannover in Germany

3. Chalcogens ●The term calcogen in greek is literally “copper former” but can be translated to “ore former” or, more commonly, “chalk former” ●The characteristics of chalcogens vary dramatically because the group crosses the line between metals and nonmetals ●The elements are mostly solids at room temperature, excluding oxygen, which is a gas

4. Oxygen ●Discovered in 1774 by Joseph Priestly in Wiltshire England after he did experiments with HgO (mercuric oxide). He found out that by exposing the chemical to sunlight it liberated a gas that is now recognized as pure oxygen (O 2 ). ●The name comes from the greek ‘oxy genes’ meaning ‘acid forming’. ●Oxygen is a diatomic element naturally found as a colorless, odorless gas. It is also highly flammable. ●It makes up 21% of the Earth’s atmosphere, 49% by mass of the Earth’s crust, and ⅔ of the human body. ●The oxygen content in the atmosphere is at the perfect concentration so organisms don’t die of asphyxiation or spontaneously combust. ●O 16 is the most abundant isotope (99.762%) ●Used in the production of a wide variety of chemicals including nitric acid and hydrogen peroxide. ●Used most commonly in the steel industry for welding and cutting metal.

5. Sulfur ■General Characteristics ○Assryian texts from 700-600B.C. state sulfur is a “product of the riverside” ○Sulfur deposits were found along the rivers. ○Discovered in Northern Iraq ■Physical Characteristics ○Solid at room temperature ○Nonmetal ○Yellow brittle crystals ○Density = 2.07g/cm 3 ○Melting Point = 115.21 o C, Boiling Point = 444.62 o C ■Unique Facts ○Used for organic insecticides, preservatives for dried fruits, and fertilizers ○Extracted from the Earth by Frasch processes. 16 S 32.065 SULFUR

6. Selenium ●Discovered in 1817 by Jöns Jacob Berzelius after observing a red-brown sediment collected as a bi product of sulfuric acid. ●The name comes from ‘selene’ the Greek name for moon. ●Selenium is a metalloid naturally found in either a silvery metal or a red powder. ●It is an essential trace element in humans however in excess can act as a carcinogen. ●Most abundant isotopes: 80 Se(49.6%), 78 Se(23.7%), 76 Se(9.4%). ●Used as an additive to glass to make it clear. ●Used in photocells, solar cells, and photocopiers because it is useful in converting light energy to electrical energy.

7. Tellurium ■General Characteristics ○Discovered by Franz Joseph Miller von Reichstein in Romania, 1783 ○Found in gold ores ○He was intrigued by the metallic sheen in gold ore and discovered Tellurium ■Physical Characteristics ○Solid at room temperature ○Grey powder ○Density = 6.232g/cm 3 ○Melting Point = 449.51 o C, Boiling Point = 988 o C ■Unique Facts ○Used with copper and stainless steel to improve machinability ○Very toxic metalloid ○If workers mining Tellurium are exposed to tellurium, they get “tellurium breath” that smells like garlic breath. 52 Te 127.60 TELLURIUM

8. Polonium-Po ●Named for the country of Poland, where it was discovered ●A silvery grey radioactive semimetal which is a solid at room temperature ●Melting point: 254°C, 489°F ●Boiling point: 962°C, 1764°F ●Density: 9.32 g/cm 3 ●Used as an alpha emitter ●Used as a source of heat in space equipment ●Very rare natural element ●Mendeleev predicted Po would exist because of a missing space on his periodic table ●In 1898 Marie Curie and husband Pierre extracted some Polonium from pitchblende (uranium oxide, U 3 O 8 )