Does anyone know where I can find the chemical foermula and structure of selenium?
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Selenium is an element, with symbol Se.  Atomic number 34, atomic mass 79.  In neutral state, has the electronic structure 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p4.  Can form both covalent compounds, where it can be either the central atom or not, or can ionize, usually to the -2 state, to form salts.
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Here is one : http://en.wikipedia.org/wiki/Periodic_table
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Check this link http://www.webelements.com/\nGood luck
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The closest thing you will find are sites like chemifinder and chemical catalog sites such as aldrich.
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See http://www.element-collection.com/
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http://www.chemicalelements.com/elements/k.html\n\nhttp://www-spof.gsfc.nasa.gov/stargaze/Q6.htm
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www.chemfinder.com might help
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http://periodic.lanl.gov/default.htm\n\nClick on the element, and it's in the top section of information. To write out the electron configuration for every element would take quite a while, so if you need it for a specific element or a few elements, I'd reccomend asking just for the few.
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http://www.chemistrystore.com/index.html\nhas ingredients and recipes
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Selenium exists in several allotropic forms; red selenium is monoclinic and contains Se8 rings. It has a melting point of 180C and a relative density of 4.45. The grey (metallic) form of selenium is formed when other varieties are heated to 200C; this has a melting point of 220C and a relative density of 4.80. Selenium is widely distributed, mainly as the selenides of heavy metals, but only has an abundance of 0.05 ppm in the earth's crust. The metal burns in air and is unaffected by water. It is soluble in alkalis and concentrated nitric acid. \n\nThe electrical properties of selenium are of particular interest as it is both photovoltaic (i.e. it becomes an electrical conductor when exposed to light or ultra violet radiation) and photoconductive (i.e. the electrical conductivity increases with increasing illumination). These properties mean that selenium has applications in the electronics industry (e.g. in the manufacture of photoelectric cells and solar cells). Selenium is used in the ceramics and glass industries (in the latter the element being used as a decoloriser and also in the manufacture of red glasses and enamels). Selenium is an important trace element for humans, the average body containing approximately 14 mg.
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http://www.sciencentral.com/articles/view.php3?article_id=218391915&cat=2_4\n\nIs that what you are looking for?
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No. Your best bet is chemfinder.com. You can also find a lot of chemical data on wikipedia. I have to make a table of chemicals for all of my labs and I use those two sites.
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Review the chemistry and science links at the given reference.  Also, www.acs.org is good.
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here are some useful sites visit them-\n\nhttp://www.stolaf.edu/people/hansonr/mo/x-ray.html\n\nhttp://news.uns.purdue.edu/html4ever/9804.Crystallography.html
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http://www.chem1.com/acad/webtext/elchem/ec2.html#DESC\n\nhttp://www.chem1.com/acad/webtext/elchem/\n\nAnd many more by a google search
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You're best off searching the NIST webbook database\n\nhttp://webbook.nist.gov\n\nhttp://www.freewebs.com/chemistryhomework
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Try searches at the following. You may need to hit the library. You might try a general web search.\n\nhttp://chemfinder.cambridgesoft.com/\n\nhttp://www.scirus.com/srsapp/\n\nhttp://www.scienceresearch.com/search/