Sodium - Na General Information Discovery Sodium was isolated by Sir Humphry Davy in 1807 in London, by the electrolysis of molten sodium hydroxide. Appearance Sodium is a soft, silvery-white metal which is generally stored in paraffin, as it oxidises rapidly when cut. Source Sodium is the sixth most abundant element on Earth, and comprises 2.6% of the Earth's crust. The most common compound is sodium chloride, but it also occurs in many minerals, among which are cryolite, zeolite and sodalite. It is never found free in nature, due to its great reactivity. It is obtained commercially by the electrolysis of dry molten sodium chloride. Uses Metallic sodium is used in the manufacture of sodamide and esters, and in the preparation of certain organic compounds. Other uses of the metal include descaling and purifying metals, and alloy formation. One alloy of sodium with potassium is an important heat transfer agent. Sodium compounds are important in several industries, including paper, glass, soap, textile, petroleum and metal. Salt is also of vital nutritional importance. Biological Role Sodium is essential to all animals, and this has been recognised since prehistoric times. Although it is considered non-toxic, too much salt in the diet has been linked to high blood pressure under certain circumstances. General Information Sodium is very reactive, and should be handled with care. It floats on water, decomposing it with the evolution of hydrogen and the formation of sodium hydroxide. It may or may not ignite spontaneously on the water, depending on the amount of metal exposed to the water. It normally does not spontaneously ignite in air at temperatures below 115°C.

	Physical Information
	Atomic Number		11
	Relative Atomic Mass (12C=12.000)		22.990
	Melting Point/K		370.96
	Boiling Point/K		1156.1
	Density/kg m-3		971 (273K)
	Ground State Electron Configuration		[Ne]3s1
	Electron Affinity(M-M-)/kJ mol-1		-21

	Key Isotopes
	nuclide	22Na	23Na	24Na
	atomic mass	21.994	22.990	23.991
	natural abundance	0%	100%	0%
	half-life	2.602 yrs	stable	15.0 h

Other Information
Enthalpy of Fusion/kJ mol-1		2.64
Enthalpy of Vaporisation/kJ mol-1		99.2
Oxidation States
main	Na+1
others	Na-1 (in NH3 liq)

	Ionisation Energies/kJ mol-1
	M - M+	495.8
	M+ - M2+	4562.4
	M2+ - M3+	6912
	M3+ - M4+	9543
	M4+ - M5+	13353
	M5+ - M6+	16610
	M6+ - M7+	20114
	M7+ - M8+	25490
	M8+ - M9+	28933
	M9+ - M10+	141360