Erbium - Er General Information Discovery Erbium was discovered by C.G. Mosander in 1842 in Stockholm, Sweden. It was first produced in reasonably pure form in 1934 by Klemm and Bonner. Appearance Erbium is a silver-grey metal, and is soft and malleable. Source Erbium is found principally in the minerals monazite and bastnaesite, from which it can be extracted by ion exchange and solvent extraction. Uses Erbium is occasionally used in infra-red absorbing glass. Added to vanadium, it lowers the hardness and improves the workability. Otherwise it is little used. Biological Role Erbium has no known biological role, and has low toxicity. General Information Erbium slowly tarnishes in air, reacts slowly with water and reacts with acids.

	Physical Information
	Atomic Number		68
	Relative Atomic Mass (12C=12.000)		167.26
	Melting Point/K		1802
	Boiling Point/K		3136
	Density/kg m-3		9066 (298K)
	Ground State Electron Configuration		[Xe]4f126s2
	Electron Affinity(M-M-)/kJ mol-1		-50

	Key Isotopes
	nuclide	162Er	164Er	166Er	167Er	168Er
	atomic mass	161.9	163.9	165.9	166.9	167.9
	natural abundance	0.14%	1.56%	33.4%	22.9%	27.1%
	half-life	stable	stable	stable	stable	stable
	nuclide	169Er	170Er	171Er
	atomic mass		169.9
	natural abundance	0%	14.9%	0%
	half-life	9.4 days	stable	7.52 h

Other Information
Enthalpy of Fusion/kJ mol-1		17.2
Enthalpy of Vaporisation/kJ mol-1		280
Oxidation States
Er+3

	Ionisation Energies/kJ mol-1
	M - M+	588.7
	M+ - M2+	1151
	M2+ - M3+	2194
	M3+ - M4+	4115
	M4+ - M5+
	M5+ - M6+
	M6+ - M7+
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+