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16 S 32.065(5)

Sulfur

Nonmetal
Symbol S
Atomic Number 16
Atomic Weight 32.065(5)
CAS Registry ID 7704-34-9
Group Name Chalcogen
Period Number 3
Block p-block
State at STP Solid

Description

Sample of Sulfur ⌕ Enlarge Image

Sulfur is a nonmetal that is a lemon yellow solid in its natural state. Sulfur has an atomic weight of 32.065, a melting point of 239.38 °F, and a boiling point of 832.5 °F. Sulfur has an odor that is sometimes characterized as a ‘rotten egg’ smell. Some common uses of sulfur include: as a major ingredient in black gunpowder, as a fungicide, as a bleaching agent of paper products, in the manufacture of cellophane and rayon, and in the vulcanization of rubber.

Isolation

Pure sulfur deposits are located throughout the world near hot springs and volcanic sites. However, some isolation procedures can be used to extract pure sulfur from other sources.

Sulfur ⌕ Enlarge Image

Large scale isolation of sulfur for commercial purposes is carried out through two main processes: the Claus process, and the Frasch process. The Clause process extracts sulfur from hydrogen sulfide that is produced through hydro-desulfurization of natural gas and petroleum; there are two steps two the Claus process. In the first step, the thermal process, hydrogen sulfide gas is heated in a combustion chamber to 1562 °F. Air is injected into the chamber to complete the reaction and produce sulfur dioxide and water. In the second step of the Claus process, the catalytic step, sulfur dioxide is reacted with hydrogen sulfur in a heated combustion chamber. Cooling temperatures cause condensation, and pure elemental sulfur and water are the products of the reactions.

The Fracsh process of sulfur isolation uses sulfur from underground reserves. During this process, holes are dug down into the sulfur deposits, pipes are interested into the holes, and superheated steam is forced down the pipes into the sulfur. The sulfur melts, and it is removed by pumping more air down a central pipe bringing the sulfur up to the surface.

General

NameSulfur
SymbolS
Number16
Chemical seriesNonmetal
Group16
Period3
Blockp
Appearancelemon yellow brick
Standard atomic weight32.065(5) g·mol⁻¹
Electron configuration[Ne] 3s2 3p4
Electrons per shell2, 8, 6

Atomic Properties

Crystal structureorthorhombic
Oxidation states−1, ±2, 4, 6 (strongly acidic oxide)
Electronegativity2.58 (Pauling scale)
Ionization energies1st: 999.6 kJ·mol−1
2nd: 2252 kJ·mol−1
3rd: 3357 kJ·mol−1
Atomic radius100 pm
Atomic radius (calc.)88 pm
Covalent radius102 pm
Van der Waals radius180 pm

Physical Properties

Phasesolid
Density (near r.t.)(alpha) 2.07 g·cm−3
Liquid density at m.p.1.819 g·cm−3
Melting point388.36 K (115.21 °C, 239.38 °F)
Boiling point717.8 K (444.6 °C, 832.3 °F)
Critical point1314 K, 20.7 MPa
Heat of fusion(mono) 1.727 kJ·mol−1
Heat of vaporization(mono) 45 kJ·mol−1
Heat capacity(25 °C) 22.75 J·mol−1·K−1

Miscellaneous

Magnetic ordering
Electrical resistivity(20 °C) (amorphous) 2×1015Ω·m
Thermal conductivity(300 K) (amorphous) 0.205 W·m−1·K−1
Thermal expansion
Speed of sound (thin rod)
Young's modulus
Shear modulus
Bulk modulus7.7 GPa
Poisson ratio
Mohs hardness2.0
Vickers hardness
Brinell hardness