Sulfur - S General Information Discovery Sulfur was known to ancient civilisations, and referred to in Genesis as brimstone. Appearance Sulfur exists as several allotropes, of which orthorhombic sulfur is the most stable. It is a pale yellow, brittle, odourless solid. Source Sulfur is widely distributed in nature as iron pyrites, galena, gypsum, Epsom salts and many other minerals. It is commercially recovered from wells sunk into the salt domes along the Gulf Coast of the USA, and from the Alberta gas fields. It is also mined in Poland. The Frasch Process is used to force superheated water into the wells to melt the sulfur, which can then be recovered chemically. Sulfur can also be recovered from natural gas and crude oil by conversion into hydrogen sulfide, from which sulfur is liberated. Uses Sulfur is used in the vulcanisation of black rubber, as a fungicide and in black gunpowder. Most, however, is used in the production of sulfuric acid, which is the most important bulk chemical manufactured in industrialised countries. Biological Role Sulfur is essential to life as a component of fats, body fluids and bones. It is non-toxic as the element and in the form of sulfate, but carbon disulfide, hydrogen sulfide and sulfur dioxide are all toxic, especially hydrogen sulfide which can cause death by respiratory paralysis. General Information Sulfur occurs in several allotropic forms whether in the liquid, solid or gaseous state. Amorphous or plastic sulfur is obtained by fast cooling of the crystalline form, and is thought to have a helical structure with eight atoms per spiral. Crystalline sulfur is made up of rings, each containing eight sulfur atoms.

	Physical Information
	Atomic Number		16
	Relative Atomic Mass (12C=12.000)		32.066
	Melting Point/K		386
	Boiling Point/K		717
	Density/kg m-3		2070 (293K)
	Ground State Electron Configuration		[Ne]3s23p4
	Electron Affinity(M-M-)/kJ mol-1		-200.4

	Key Isotopes
	nuclide	32S	33S	34S	35S	36S
	atomic mass	31.972	32.971	33.968	34.969	35.967
	natural abundance	95.02%	0.75%	4.21%	0%	0.02%
	half-life	stable	stable	stable	87.9 days	stable

Other Information
Enthalpy of Fusion/kJ mol-1		1.23
Enthalpy of Vaporisation/kJ mol-1		9.62
Oxidation States
main	S-2, S0, S+6
others	S-1, S+1, S+2, S+3,
	S+4, S+5
Covalent Bonds /kJ mol-1
S - H	347
S - C	272
S = C	476
S - O	265
S = O	525
S - F	328
S - Cl	255
S - S	226

	Ionisation Energies/kJ mol-1
	M - M+	999.6
	M+ - M2+	2251
	M2+ - M3+	3361
	M3+ - M4+	4564
	M4+ - M5+	7013
	M5+ - M6+	8495
	M6+ - M7+	27106
	M7+ - M8+	31669
	M8+ - M9+	36578
	M9+ - M10+	43138