Dubnium - Db General Information Discovery Dubnium was discovered in 1970 by various parties at both Berkeley, California and Dubna, Moscow. Appearance Unknown, but probably metallic grey in appearance. Source A transuranium element created by bombarding 249Cf with 15N nuclei. Uses Unknown. Biological Role None. General Information Two separate groups have claimed to be the discoverers of the element, due to two differing isotopes. Credit has been shared between both. Dubnium is a synthetic element created via nuclear bombardment. Few atoms have ever been made and the properties of dubnium are very poorly understood. It is a radioactive metal and is of research interest only. Interestingly, it is unlikely that any of the transuranium elements will ever be synthesised in large quantities due to the danger from their high radioactivity. 249Cf + 15N ®  260Db + 4n

	Physical Information
	Atomic Number		105
	Relative Atomic Mass (12C=12.000)		262.11
	Melting Point/K		not available
	Boiling Point/K		not available
	Density/kg m-3		29,000
	Ground State Electron Configuration		[Rn]5f146d37s2
	Electron Affinity(M-M-)/kJ mol-1		not available

	Key Isotopes
	nuclide	255Db	257Db	258Db	259Db	260Db
	atomic mass		257.11	258.11	259.11	260.11
	natural abundance	0%	0%	0%	0%	0%
	half-life	approx	1.3 secs	4.4 secs	approx	1.5 secs
		1.5 secs			1.2 secs
	nuclide	261Db	262Db	263Db
	atomic mass	261.11	262.11
	natural abundance	0%	0%	0%
	half-life	1.8 secs	34 secs	27 secs

Other Information
Enthalpy of Fusion/kJ mol-1		n/a
Enthalpy of Vaporisation/kJ mol-1		n/a
Oxidation States
Db+5 suggested as most stable.

	Ionisation Energies/kJ mol-1
	M - M+	640 (est)
	M+ - M2+
	M2+ - M3+
	M3+ - M4+
	M4+ - M5+
	M5+ - M6+
	M6+ - M7+
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+