Americium - Am General Information Discovery Americium was discovered by G.T. Seaborg, R.A. James, L.O. Morgan and A. Ghiorso in 1944 in Chicago, USA. Appearance Americium is a radioactive, silvery metal. It tarnishes slowly in dry air at room temperature. Source Americium can be prepared chemically by the reduction of americium (III) fluoride with barium, or americium (IV) oxide with lanthanum. However, it is produced in nuclear reactors by the neutron bombardment of plutonium, and this is the greatest source of the element. Uses Americium has few uses. It is of interest as it is part of the decay sequence that occurs in nuclear power production. Biological Role Americium has no known biological role. It is toxic due to its radioactivity. General Information Americium is attacked by air, steam and acids, but not by alkalis.

	Physical Information
	Atomic Number		95
	Relative Atomic Mass (12C=12.000)		243 (radioactive)
	Melting Point/K		1267
	Boiling Point/K		2880
	Density/kg m-3		13670 (293K)
	Ground State Electron Configuration		[Rn]5f7s2

	Key Isotopes
	nuclide	241Am	243Am
	atomic mass	241.06	243.06
	natural abundance	0%	0%
	half-life	458 yrs	7.4x103 yrs

Other Information
Enthalpy of Fusion/kJ mol-1		14.4
Enthalpy of Vaporisation/kJ mol-1		238.5
Oxidation States
main	AmIII
others	AmII, AmIV, AmV, AmVI
Covalent Bonds /kJ mol-1
not applicable

	Ionisation Energies/kJ mol-1
	M - M+	578.2
	M+ - M2+
	M2+ - M3+
	M3+ - M4+
	M4+ - M5+
	M5+ - M6+
	M6+ - M7+
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+