Technetium - Tc General Information Discovery Technetium was discovered by C. Perrier and E.G. Segre in 1937 in Palermo, Italy. It was the first element to be produced artificially. Appearance Technetium is a silvery-grey metal that tarnishes slowly in moist air. It is usually obtained as a grey powder. Source The metal is produced in tonne quantities from the fission products of uranium nuclear fuel. Uses The gamma ray emitting technetium-99m (metastable) is widely used for diagnostic studies. Several chemical forms are used to image different parts of the body. Technetium is a remarkable corrosion inhibitor for steel, and can protect steel by the addition of very small amounts. This use is limited to closed systems due to technetium's radioactivity. Biological Role Technetium has no known biological role. It is toxic as a radioactive element. General Information Technetium is an excellent superconductor at 11 K and below. It resists oxidation, burns in oxygen and reacts with nitric and sulfuric acids.

	Physical Information
	Atomic Number		43
	Relative Atomic Mass (12C=12.000)		98.91
	Melting Point/K		2445
	Boiling Point/K		5150
	Density/kg m-3		11500 (293K)
	Ground State Electron Configuration		[Kr]4d55s2
	Electron Affinity(M-M-)/kJ mol-1		-96

	Key Isotopes
	nuclide	97Tc	98Tc	99Tc
	atomic mass		97.911	98.90
	natural abundance	0%	0%	0%
	half-life	2.6x106 yrs	1.5x106 yrs	2.12x105 yrs

Other Information
Enthalpy of Fusion/kJ mol-1		23.81
Enthalpy of Vaporisation/kJ mol-1		585.22
Oxidation States
main	Tc+4, Tc+5, Tc+7
others	Tc-1, Tc0, Tc+6

	Ionisation Energies/kJ mol-1
	M - M+	702
	M+ - M2+	1472
	M2+ - M3+	2850
	M3+ - M4+	4100
	M4+ - M5+	5700
	M5+ - M6+	7300
	M6+ - M7+	9100
	M7+ - M8+	15600
	M8+ - M9+	17800
	M9+ - M10+	19900