Periodic Table of Elements

02/05/09

Ar

Argon

Atomic Number

18

Atomic Symbol

Ar

	Name	Argon
	Meaning	Named for the Greek word 'argos' meaning 'lazy'

Group

Noble gases

Atomic Weight

39.948

Density, g/cubic cm at STP

0.00178375

Melting Point, °C

-189.19

Boiling Point, °C, 1 atm

-186

Naturally Occurring Isotopes

Ar-36, Ar-38, Ar-40

Discoverer

Rayleigh and Ramsay

Year

1895

Ionization Energy, eV

15.7596

Configuration

[Ne] 3s2 3p6

Description

colorless, odorless gas at STP

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