Group VIA The Chalcogens

1. Group VIAThe Chalcogens By Van, Alex, Alex, and Logan

2. Elements • Oxygen • Sulfur • Selenium • Tellurium • Polonium • Ununhexium

3. Selenium (Se) • Discovered in 1818 by Berzelius • Named for Greek moon “selene” • Atomic Number: 34 • Atomic Mass: 78.96 • Member of the Sulfur Family

4. http://en.wikipedia.org/wiki/Image:Selen_1.jpg Properties • Exists in several allotropic forms, three generally recognized: • Red amorphous powder, • Red crystalline material, • Gray crystalline metal like form called metallic selenium. • Red in powder form • Black in vitreous form • Crystalline monoclinic selenium is a deep red • Crystalline hexagonal selenium, is a metallic gray • http://www.lenntech.com/Periodic-chart-elements/Se-en.htm

5. Properties continued • Good photovoltaic and photoconductive • Boiling Point: 690ºC • Melting Point: 170 - 217ºC

6. Uses • Xerography for reproducing and copying documents • Glass Industry • Decolorize Glass • Create ruby-colored glass • Make enamels • Rectifiers • To make photocells, solar cells www.colonialcandle.com

7. Uses continued • Photographic toner • Additive to stainless steel

8. Where it is Found? • Very Rare • Rarer than Silver • Found in about 40 selenium containing minerals like copper, zinc and lead • Selenium deficiency in the Northwest

9. Polonium (Po) • Highly rare and radio active • Discovered in 1898 by Marie and Pierre Curie • Atomic number: 84 • Atomic mass: 209

10. Properties • Volatile metal • Radio active • 254° C melting point • 962°C boiling point • Cubic Structure www.3dchem.com

11. www.jaxa.jp Uses • Lightweight heat source for thermoelectric power in space satellites. • Eliminating static charges in textile mills • Brushes for removing dust from photographic films

12. Where is it Found? • Extremely rare • Can created when you bombard natural bismuth with neutrons.

13. Oxygen Recognized by Antoine Lavoisier in 1777 Atomic Number: 8 Atomic Mass: 15.999

14. Where is Oxygen Found? • Water H2O • Air 20.95% • Plants photosynthesis end product • Ozone Molecule consisting of three oxygen atoms

15. Oxygen’s Forms Gas Liquid Mineral Example: Cassiterite Made of tin and oxygen Clear Blue

16. How is it Used? Necessary for life on Earth Accelerates Combustion Iron and Steel Industries

17. Tellurium

18. Basic Info • Tellurium has an atomic weight of 127.60g • Tellurium is a solid • Tellurium has a grayish or metallic color

19. Where is it found? • Tellurium is not a commonly seen element but it is commercially available • Tellurium is seen as a byproduct of copper

20. Funny Fact • Less than 0.0001 of Tellurium in the air will cause any living organisms to have “garlic breath”

21. Sulfur 16 S 32.065 • Sulfur is solid at room temperature, and is bright yellow • It is the tenth most common element • In a certain form it will burn when mixed with O2 Sulfur • Melts at 115 °C • Turns into a red liquid • Boils at 444 °C • Burns with a blue flame • While burning it emits sulfur dioxide

22. Various Uses • Sulfur powder is extractable from pyrite by the Frasch process, which uses hot water and air. • Batteries, fireworks, preservatives • Sulfuric acid • Sulfur is used to vulcanize rubber • Exists in most living cells

23. Sources • "Fact about Oxygen". September, 27, 2007 <http://www.facts-about.org.uk/science-element-oxygen.htm>. • "Oxygen: uses". Pearson Education. September, 30, 2007 <http://www.infoplease.com/ce6/sci/A0860185.html>. • A Periodic Table of the Elements at Los Alsmos National Laboratory.1 Los Alamos National Laboratory's Chemistry Division. 30 Sep. 2007 <http://www.periodic.lanl.gov/default.htm>. • "Selenium." Selenium (Se) -Chemical Porperties, Health and Environmental Effects.1 Lenntech. 30 Sep. 2007 <http://www.lenntech.com/Periodic-chart-elements/Se-en.htm>. • And of course Wikipedia