By: Mariko 8th Grade Mill Valley Middle School	Facts Properties History Production Uses Glossary Bibliography
Facts Chemical Symbol Se Atomic Number 34 Atomic Mass 79 Group 16 Period 4 Protons/ Electrons 34 Nuetrons 45 Melting Point 490.2k State Solid Shells 2, 8, 18, 6 Color Black, Gray, Red Toxic Yes Characteristics 6 Forms Number of Isotopes 6 Boiling Point 958k Electron Configuration [Ar]3d10 4s2 4p4	Properties Selenium can exist in three different forms; gray, red and black. If it is in red form, then it will appear to be a ruby red, glass like solid. If it's in black form then it will black and in vitreous form. Selenium can go from a.c. to d.c. electricity, and is often used in rectifiers. Selenim is known to be close to non-toxic, and and essential trace element, as long as it's in elemental form. Although, there is also Hydrogen, Selenide, and other compounds of Selenium, that are very toxic. They are similar ot Arsenic in their physilogical reactions. Selenium has six stale isotopes, but fifteen others have been characterized. It is part of the Sulfur family. It's lilke Sulfur in physical form, and in it's compunds.
History Selenium was first discovered by Jon Jakob Berzelius, a swedish chemist. He found it in in 1817 Berzelius associated Selenium with Tellurium, another element. Tellurium means earth in Greek, so he named Selenium after Selene, which mean moon in Greek. Berzelius also named Eucairite, a mineral that has a lot of Selenium.
Production Selenium is in very few minerals, the minerals is which it is found in in rare minerals like Crooksite and Clausthalite. The aroded metal from electrolyic copper refineries make the most Selenium in the world. Another way commercial Selenium is the manufacturing of Sulfuric acid. Another way to recover Selenium is to roast the muds with soda or sulfuric acid, or by melting them with soda and Niter.
Uses Selenium is used in may objects that we use in everyday life. Some of them are: light meters, copy machines, solar cells, and anit-dandruff shampoos. These are only some of the objects it's used in, very small amounts of this element is used in more obscure objects.
Glossary Isotopes- An atom of an element that has the same number of protons and electrons as others, Atom- An atom is a unit which makes up all materials and can contain protons, nuetrons and electrons. Atomic Mass- Atomic mass is the average mass of all the known isotopes in an atom. Atomic Number- The atomic number is the number of protons and electrons in an atom. Element- An element is a substance composed of atoms, and cannot be broken down into a simpler substance.
Bibliography Heiserman, David. Exploring Chemical Elements and Their Compounds. San Francisco. C. 1992 Stewertka, Albert. A Guide to the Elements. New York. C. 1998 Chemicool Periodic Table Environmental Chemistry Periodic Table Periodic Table of the Elements Pictorial Periodic Table Web Elements Periodic Table Image found at: www.ets.uidaho.edu/ che470/se_info.htm Image found at: www.asarco.com/products99/special/ purity_selenium.html Image found at: library.thinkquest.org/12909/Selenium.html Image found at: www.goacom.com/goatoday/ 98/mar/bnews.html  Animation found at: nautilus.fis.uc.pt/st2.5/scenes-e/ elem/e05295.html     ------------------------------------------------------------------------