Periodic Table of Elements

02/05/09

La

Lanthanum

Atomic Number

57

Atomic Symbol

La

	Name	Lanthanum
	Meaning	Name is from the Greek word 'lanthanein' meaning to 'escape notice'

Group

Rare earth

Atomic Weight

138.9055

Density, g/cubic cm at STP

6.145

Melting Point, °C

920

Boiling Point, °C, 1 atm

3457

Naturally Occurring Isotopes

La-138, La-139

Discoverer

Mosander

Year

1839

Ionization Energy, eV

5.5769

Configuration

[Xe] 5d 6s2

Description

Lustrous grey

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