Periodic Table of Elements

02/05/09

Se

Selenium

Atomic Number

34

Atomic Symbol

Se

	Name	Selenium
	Meaning	Named for the Greek goddess of the moon, Selene

Group

Non-metals

Atomic Weight

78.96

Density, g/cubic cm at STP

4.809

Melting Point, °C

221

Boiling Point, °C, 1 atm

685

Naturally Occurring Isotopes

Se-74, -76, -77,- 80, -82

Discoverer

Berzelius

Year

1817

Ionization Energy, eV

9.7524

Configuration

[Ar] 3d10 4s2 4p4

Description

Dull grey

Information Selenium is a nonmetal that reacts with other elements to produce a wide range of compounds known as Selenides. It also exists in the form of a red allotrope. Joseph's Element Collection Joseph has not yet obtained a sample of Selenium. References: Holden, Norman E. (March 30, 2004). "History of the origin of the chemical elements and their discoverers." National Nuclear Data Center. Retrieved October 7, 2005 from http://www.nndc.bnl.gov/content/elements.html "List of elements by boiling point." (September 22, 2005). Wikipedia. Retrieved October 9, 2005 from http://en.wikipedia.org/wiki/List_of_elements_by_boiling_point "List of elements by density." (September 22, 2005). Wikipedia. Retrieved October 9, 2005 from http://en.wikipedia.org/wiki/List_of_elements_by_density "List of elements by melting point." (September 22, 2005). Wikipedia. Retrieved October 9, 2005 from http://en.wikipedia.org/wiki/List_of_elements_by_melting_point "NIST chemistry webBook." (2005). National Institute of Standards and Technology. Retrieved October 6, 2005 from http://webbook.nist.gov/chemistry/ Zucker, M.A.; Kishore, A. R.; Sukumar, R.; and Dragoset, R. A. (July 2005). "Elemental data index."  National Institute of Standards and Technology. Retrieved October 7, 2005 from http://physics.nist.gov/PhysRefData/Elements/cover.html