Gallium - Ga General Information Discovery Gallium was discovered by P.-E. Lecoq de Boisbaudran in 1875 in Paris. Mendeléev predicted and described this element, and called it ekaaluminum. Appearance Gallium is a silvery, glass-like, soft metal. Source Gallium is present in trace amounts in the minerals diaspore, sphalerite, germanite, bauxite and coal. The free metal can be obtained by electrolysis of a solution of gallium(III) hydroxide in potassium hydroxide. Uses Gallium readily alloys with most metals, and is used especially in low-melting alloys. It has a high boiling point, which makes it ideal for recording temperatures that would vaporise a thermometer. It has found recent use in doping semiconductors and producing solid-state devices such as transistors. Biological Role Gallium has no known biological role. It is non-toxic. General Information Gallium reacts with acids and alkalis. It has the longest liquid range of all elements, and can be liquid near room temperatures - it can melt in the hand. It also expands as it freezes, which is unusual for a metal, by 3.1%. Gallium wets glass or porcelain, and forms a brilliant mirror when painted on glass.

	Physical Information
	Atomic Number		31
	Relative Atomic Mass (12C=12.000)		69.723
	Melting Point/K		303
	Boiling Point/K		2676
	Density/kg m-3		5907 (293K)
	Ground State Electron Configuration		[Ar]3d104s24p1
	Electron Affinity(M-M-)/kJ mol-1		-36

	Key Isotopes
	nuclide	67Ga	69Ga	71Ga	72Ga
	atomic mass		68.926	70.925
	natural abundance	0%	60.1%	39.9%	0%
	half-life	78.1 h	stable	stable	14.1 h

Other Information
Enthalpy of Fusion/kJ mol-1		5.59
Enthalpy of Vaporisation/kJ mol-1		270.3
Oxidation States
main	Ga+3
others	Ga+1, Ga+2

	Ionisation Energies/kJ mol-1
	M - M+	578.8
	M+ - M2+	1979
	M2+ - M3+	2963
	M3+ - M4+	6200
	M4+ - M5+	8700
	M5+ - M6+	11400
	M6+ - M7+	14400
	M7+ - M8+	17700
	M8+ - M9+	22300
	M9+ - M10+	26100