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Sulfur

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                16             phosphorus ← sulfur → chlorine
                 O
                ↑
                S
                ↓
                Se

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                        Name, Symbol, Number sulfur, S, 16
                                                 Chemical series nonmetals
                                             Group, Period, Block 16, 3, p
                                                   Appearance lemon yellow
                                              Atomic mass 32.065 (5) g/mol
                                     Electron configuration [Ne] 3s^2 3p^4
                                               Electrons per shell 2, 8, 6
                                                       Physical properties
                                                               Phase solid
                               Density (near r.t.) (alpha) 2.07 g·cm^−3
                                Density (near r.t.) (beta) 1.96 g·cm^−3
                               Density (near r.t.) (gamma) 1.92 g·cm^−3
                                   Liquid density at m.p. 1.819 g·cm^−3
                                                   Melting point 388.36  K
                                                (115.21 ° C, 239.38 ° F)
                                                     Boiling point 717.8 K
                                                  (444.6 ° C, 832.3 ° F)
                                           Critical point 1314 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

   CAPTION: Vapor pressure

                                          P/Pa   1  10  100 1 k 10 k 100 k
                                         at T/K 375 408 449 508 591   717

                                                         Atomic properties
                                            Crystal structure orthorhombic
                                          Oxidation states −1, ±2, 4, 6
                                                   (strongly acidic oxide)
                                    Electronegativity 2.58 (Pauling scale)
                                                       Ionization energies
                                           ( more) 1st: 999.6 kJ·mol^−1
                                                    2nd: 2252 kJ·mol^−1
                                                    3rd: 3357 kJ·mol^−1
                                                      Atomic radius 100 pm
                                               Atomic radius (calc.) 88 pm
                                                    Covalent radius 102 pm
                                               Van der Waals radius 180 pm
                                                             Miscellaneous
                                                 Magnetic ordering no data
                               Electrical resistivity (20 °C) (amorphous)
                                                            2×10^15 Ω·m
                                  Thermal conductivity (300 K) (amorphous)
                                                   0.205 W·m^−1·K^−1
                                                      Bulk modulus 7.7 GPa
                                                         Mohs hardness 2.0
                                             CAS registry number 7704-34-9
                                                         Selected isotopes

                  CAPTION: Main article: Isotopes of sulfur

                                 iso    NA   half-life DM  DE ( MeV)  DP
                                 ^32S 95.02% S is stable with 16 neutrons
                                 ^33S 0.75%  S is stable with 17 neutrons
                                 ^34S 4.21%  S is stable with 18 neutrons
                                 ^35S syn    87.32 d   β^- 0.167     ^35Cl
                                 ^36S 0.02%  S is stable with 20 neutrons

                                                                References

   Sulfur or sulphur ( IPA: /ˈsʌlfə(ɹ)/, see spelling below) is the
   chemical element in the periodic table that has the symbol S and atomic
   number 16. It is an abundant, tasteless, odorless, multivalent
   non-metal. Sulfur, in its native form, is a yellow crystalline solid.
   In nature, it can be found as the pure element or as sulfide and
   sulfate minerals. It is an essential element for life and is found in
   two amino acids, Cysteine and Methionine. Its commercial uses are
   primarily in fertilizers, but it is also widely used in gunpowder,
   matches, insecticides and fungicides.

Notable characteristics

   A piece of sulfur melts to a blood-red liquid. When burned, it emits a
   blue flame.
   Enlarge
   A piece of sulfur melts to a blood-red liquid. When burned, it emits a
   blue flame.

   At room temperature, sulfur is a soft bright yellow solid. Although
   sulfur is blamed for the smell—, e.g. of rotten eggs— elemental sulfur
   has only the faintest odor (the odour associated with rotten eggs is
   actually due to hydrogen sulfide and organic sulfur compounds). It
   burns with a blue flame that emits sulfur dioxide, notable for its
   peculiar suffocating odour. Sulfur is insoluble in water but soluble in
   carbon disulfide and to a lesser extent in other organic solvents such
   as benzene. Common oxidation states of sulfur include −2, +2, +4 and
   +6. Sulfur forms stable compounds with all elements except the noble
   gases.

   Sulfur in the solid state ordinarily exists as cyclic crown-shaped S[8]
   molecules. Sulfur has many allotropes besides S[8]. Removing one atom
   from the crown gives S[7], which is responsible for sulfur's
   distinctive yellow colour. Many other rings have been prepared,
   including S[12] and S[18]. By contrast, its lighter neighbour oxygen
   only exists in two states of allotropic significance: O[2] and O[3].
   Selenium, the heavier analogue of sulfur can form rings but is more
   often found as a polymer chain.
   The structure of the S8 molecule, two atoms are obscured in this view.
   Enlarge
   The structure of the S[8] molecule, two atoms are obscured in this
   view.

   The crystallography of sulfur is complex. Depending on the specific
   conditions, the sulfur allotropes form several distinct crystal
   structures, with rhombic and monoclinic S[8] best known.

   A noteworthy property of sulfur is that its viscosity in the molten
   sulfur, unlike most other liquids, increases with temperature due to
   the formation of polymer chains. However, after a specific temperature
   is reached, the viscosity is reduced because there is enough energy to
   break the chains.

   Amorphous or "plastic" sulfur can be produced through the rapid cooling
   of molten sulfur. X-ray crystallography studies show that the amorphous
   form may have a helical structure with eight atoms per turn. This form
   is metastable at room temperature and gradually reverts back to
   crystalline form. This process happens within a matter of hours to days
   but can be rapidly catalyzed.

Applications

   Sulfur has many industrial uses. Through its major derivative, sulfuric
   acid (H[2]SO[4]), sulfur ranks as one of the more important industrial
   raw materials. It is of prime importance to every sector of the world's
   economies.

   Sulfuric acid production is the major end use for sulfur, and
   consumption of sulfuric acid has been regarded as one of the best
   indices of a nation's industrial development. More sulfuric acid is
   produced in the United States every year than any other industrial
   chemical.

   Sulfur is also used in batteries, detergents, the vulcanization of
   rubber, fungicides, and in the manufacture of phosphate fertilizers.
   Sulfites are used to bleach paper and as a preservative in wine and
   dried fruit. Because of its flammable nature, sulfur also finds use in
   matches, gunpowder, and fireworks. Sodium or ammonium thiosulfate is
   used as photographic fixing agents. Magnesium sulfate, better known as
   Epsom salts, can be used as a laxative, a bath additive, an exfoliant,
   or a magnesium supplement for plants. Sulfur is used as the
   light-generating medium in the rare lighting fixtures known as sulfur
   lamps.

   In the late 1700s, furniture makers used molten sulfur to produce
   decorative inlays in their craft. Because of the sulfur dioxide
   produced during the process of melting sulfur, the craft of sulfur
   inlays was soon abandoned.

Biological role

   The amino acids cysteine and methionine contain sulfur, as do all
   polypeptides, proteins, and enzymes which contain these amino acids.
   This makes sulfur a necessary component of all living cells. Disulfide
   bonds between polypeptides are very important in protein assembly and
   structure. Homocysteine and taurine are also sulfur containing amino
   acids but are not coded for by DNA nor are they part of the primary
   structure of proteins. Some forms of bacteria use hydrogen sulfide
   (H[2]S) in the place of water as the electron donor in a primitive
   photosynthesis-like process. Sulfur is absorbed by plants via the roots
   from soil as the sulfate ion and reduced to sulfide before it is
   incorporated into cysteine and other organic sulfur compounds ( sulfur
   assimilation). Inorganic sulfur forms a part of iron-sulfur clusters,
   and sulfur is the bridging ligand in the Cu[A] site of cytochrome c
   oxidase. Sulfur is an important component of coenzyme A.

Environmental impact

   The burning of coal and petroleum by industry and power plants
   liberates huge amounts of sulfur dioxide (SO[2]) which reacts with
   atmospheric water and oxygen to produce sulfuric acid. This sulfuric
   acid is a component of acid rain, which lowers the pH of soil and
   freshwater bodies, resulting in substantial damage to the natural
   environment and chemical weathering of statues and architecture. Fuel
   standards increasingly require sulfur to be extracted from fossil fuels
   to prevent the formation of acid rain. This extracted sulfur is then
   refined and represents a large portion of sulfur production.

History

   Sulfur crystal from Agrigento, Sicily, Italy
   Enlarge
   Sulfur crystal from Agrigento, Sicily, Italy

   Sulfur (Sanskrit, sulvari; Latin sulfur or sulpur) was known in ancient
   times, and is referred to in the Biblical Pentateuch ( Genesis). The
   word itself probably is from the Arabic sufra meaning yellow, from the
   bright colour of the naturally occurring form, although the Sanskrit
   name for sulfur, sulvari could also be interpreted as meaning "enemy of
   copper".

   English translations of the Bible commonly refer to sulfur as
   "brimstone", giving rise to the name of 'Fire and brimstone' sermons,
   in which listeners are reminded of the fate of eternal damnation that
   awaits the nonbelieving and unrepented. It is from this part of the
   Bible that Hell is implied to "smell of sulfur", although as mentioned
   above sulfur is in fact odorless. The "smell of sulfur" usually refers
   to the odour of hydrogen sulfide, e.g. from rotten eggs. Burning sulfur
   produces sulfur dioxide, the smell associated with burnt matches.

   Homer mentioned "pest-averting sulfur" in the 8th century BC and in 424
   BC, the tribe of Boeotia destroyed the walls of a city by burning a
   mixture of coal, sulfur, and tar under them. Sometime in the 12th
   century, the Chinese invented gun powder which is a mixture of
   potassium nitrate (KNO[3]), carbon, and sulfur. Early alchemists gave
   sulfur its own alchemical symbol which was a triangle at the top of a
   cross. In the late 1770s, Antoine Lavoisier helped convince the
   scientific community that sulfur was an element and not a compound. In
   1867, sulfur was discovered in underground deposits in Louisiana and
   Texas. The overlying layer of earth was quicksand, prohibiting ordinary
   mining operations. Therefore the Frasch process was utilized.

Occurrence

   Sulfur powder.
   Enlarge
   Sulfur powder.
   Sulfur crystalites at Waiotapu hot springs, New Zealand
   Enlarge
   Sulfur crystalites at Waiotapu hot springs, New Zealand

   Elemental sulfur can be found near hot springs and volcanic regions in
   many parts of the world, especially along the Pacific Ring of Fire.
   Such volcanic deposits are currently exploited in Indonesia, Chile, and
   Japan.

   Significant desposits of elemental sulfur also exist in salt domes
   along the coast of the Gulf of Mexico, and in evaporites in eastern
   Europe and western Asia. The sulfur in these deposits is believed to
   come from the action of anaerobic bacteria on sulfate minerals,
   especially gypsum, although apparently native sulfur may be produced by
   geological processes alone, without the aid of living organisms (see
   below). However, fossil-based sulfur deposits from salt domes are the
   basis for commercial production in the United States, Poland, Russia,
   Turkmenistan, and Ukraine.

   Sulfur extracted from oil, gas and the Athabasca Oil Sands has become a
   glut on the market, with huge stockpiles of sulfur in existence
   throughout Alberta.
   Sulfur mined in Alberta, prepared for shipment at Vancouver, B. C.
   Enlarge
   Sulfur mined in Alberta, prepared for shipment at Vancouver, B. C.

   Common naturally occurring sulfur compounds include the metal sulfides,
   such as pyrite (iron sulfide), cinnabar (mercury sulfide), galena (
   lead sulfide), sphalerite (zinc sulfide) and stibnite (antimony
   sulfide); and the metal sulfates, such as gypsum (calcium sulfate),
   alunite (potassium aluminium sulfate), and barite (barium sulfate). It
   occurs naturally in volcanic emissions, such as from hydrothermal
   vents, and from bacterial action on decaying sulfur-containing organic
   matter.

   The distinctive colors of Jupiter's volcanic moon, Io, are from various
   forms of molten, solid and gaseous sulfur. There is also a dark area
   near the Lunar crater Aristarchus that may be a sulfur deposit. Sulfur
   is also present in many types of meteorites.

Compounds

   Hydrogen sulfide has the characteristic smell of rotten eggs. Dissolved
   in water, hydrogen sulfide is acidic and will react with metals to form
   a series of metal sulfides. Natural metal sulfides are common,
   especially those of iron. Iron sulfide is called pyrite, the so called
   fool's gold. Interestingly, pyrite can show semiconductor properties.
   Galena, a naturally occurring lead sulfide, was the first semiconductor
   discovered, and found a use as a signal rectifier in the "cat's
   whiskers" of early crystal radios.

   Many of the unpleasant odours of organic matter are based on
   sulfur-containing compounds such as methyl and ethyl mercaptan used to
   scent natural gas so that leaks are easily detectable. The odour of
   garlic and " skunk stink" are also caused by sulfur-containing organic
   compounds. However, not all organic sulfur compounds smell unpleasant;
   for example, grapefruit mercaptan, a sulfur-containing monoterpenoid is
   responsible for the characteristic scent of grapefruit.

   Polymeric sulfur nitride has metallic properties even though it does
   not contain any metal atoms. This compound also has unusual electrical
   and optical properties. This polymer can be made from tetrasulfur
   tetranitride S[4]N[4].

   Phosphorus sulfides are important in synthesis. For example, P[4]S[10]
   and its derivatives Lawesson's reagent and naphthalen-1,8-diyl
   1,3,2,4-dithiadiphosphetane 2,4-disulfide are used to replace oxygen
   from some organic molecules with sulfur.

   Inorganic sulfur compounds:
     * Sulfides (S^2−), a complex family of compounds usually derived from
       S^2−. Cadmium sulfide (CdS) is an example.
     * Sulfites (SO[3]^2−), the salts of sulfurous acid (H[2]SO[3]) which
       is generated by dissolving SO[2] in water. Sulfurous acid and the
       corresponding sulfites are fairly strong reducing agents. Other
       compounds derived from SO[2] include the pyrosulfite or
       metabisulfite ion (S[2]O[5]^2−).
     * Sulfates (SO[4]^2−), the salts of sulfuric acid. Sulfuric acid also
       reacts with SO[3] in equimolar ratios to form pyrosulfuric acid
       (H[2]S[2]O[7]).
     * Thiosulfates (sometimes referred to as thiosulfites or
       "hyposulfites") (S[2]O[3]^2−). Thiosulfates are used in
       photographic fixing (HYPO) as reducing agents. Ammonium thiosulfate
       is being investigated as a cyanide replacement in leaching gold.
     * Sodium dithionite, Na[2]S[2]O[4], is the highly reducing dianion
       derived from hyposulfurous/dithionous acid.
     * Sodium dithionate (Na[2]S[2]O[6]).
     * Polythionic acids (H[2]S[n]O[6]), where n can range from 3 to 80.
     * Peroxymonosulfuric acid (H[2]SO[5]) and peroxydisulfuric acids
       (H[2]S[2]O[8]), made from the action of SO[3] on concentrated
       H[2]O[2], and H[2]SO[4] on concentrated H[2]O[2] respectively.
     * Sodium polysulfides (Na[2]S[x])
     * Sulfur hexafluoride, SF[6], a dense gas at ambient conditions, is
       used as nonreactive and nontoxic propellant
     * Sulfur nitrides are chain and cyclic compounds containing only S
       and N. Tetrasulfur tetranitride S[4]N[4] is an example.
     * Thiocyanates contain the SCN^− group. Oxidation of thiocyanoate
       gives thiocyanogen, (SCN)[2] with the connectivity NCS-SCN.

   Organic sulfur compounds (where R, R', and R are organic groups such as
   CH[3]):
     * Thioethers have the form R-S-R′. These compounds are the sulfur
       equivalents of ethers.
     * Sulfonium ions have the formula RR'S-'R'", i.e. where three groups
       are attached to the cationic sulfur centre.
       Dimethylsulfoniopropionate ( DMSP; (CH[3])[2]S^+CH[2]CH[2]COO^−) is
       a sulfonium ion, which is important in the marine organic sulfur
       cycle.
     * Thiols (also known as mercaptans) have the form R-SH. These are the
       sulfur equivalents of alcohols.
     * Thiolates ions s have the form R-S^-. Such anions arise upon
       treatment of thiols with base.
     * Sulfoxides have the form R-S(=O)-R′. A common sulfoxide is DMSO.
     * Sulfones have the form R-S(=O)[2]-R′. A common sulfone is sulfolane
       C[4]H[8]SO[2].

Isotopes

   Sulfur has 18 isotopes, four of which are stable: ^32S (95.02%), ^33S
   (0.75%), ^34S (4.21%), and ^36S (0.02%). Other than ^35S, the
   radioactive isotopes of sulfur are all short lived. ^35S is formed from
   cosmic ray spallation of ^40Ar in the atmosphere. It has a half-life of
   87 days.

   When sulfide minerals are precipitated, isotopic equilibration among
   solids and liquid may cause small differences in the δS-34 values of
   co-genetic minerals. The differences between minerals can be used to
   estimate the temperature of equilibration. The δC-13 and δS-34 of
   coexisting carbonates and sulfides can be used to determine the pH and
   oxygen fugacity of the ore-bearing fluid during ore formation.

   In most forest ecosystems, sulfate is derived mostly from the
   atmosphere; weathering of ore minerals and evaporites also contribute
   some sulfur. Sulfur with a distinctive isotopic composition has been
   used to identify pollution sources, and enriched sulfur has been added
   as a tracer in hydrologic studies. Differences in the natural
   abundances can also be used in systems where there is sufficient
   variation in the ^34S of ecosystem components. Rocky Mountain lakes
   thought to be dominated by atmospheric sources of sulfate have been
   found to have different δS-34 values from lakes believed to be
   dominated by watershed sources of sulfate.

Precautions

   Carbon disulfide, carbon oxysulfide, hydrogen sulfide, and sulfur
   dioxide should all be handled with care.

   Although sulfur dioxide is sufficiently safe to be used as a food
   additive in small amounts, at high concentrations it reacts with
   moisture to form sulfurous acid which in sufficient quantities may harm
   the lungs, eyes or other tissues. In creatures without lungs such as
   insects or plants, it otherwise prevents respiration.

   Hydrogen sulfide is quite toxic (more toxic than cyanide). Although
   very pungent at first, it quickly deadens the sense of smell, so
   potential victims may be unaware of its presence until it is too late.

Spelling

   The element has traditionally been spelled sulphur in the United
   Kingdom, Ireland, Hong Kong and India, but sulfur in the United States,
   while both spellings are used in Australia, Canada and New Zealand.
   IUPAC adopted the spelling "sulfur" in 1990, as did the Royal Society
   of Chemistry Nomenclature Committee in 1992. This spelling has begun to
   replace its variant in official use, unlike aluminium, which is not
   commonly used outside North America, and which IUPAC rejected in 1990
   in favour of aluminium.

   The Latin name of the element is sulfur with an F. Since it is an
   original Latin name and not a Classical Greek loan, the fricative
   phoneme is indeed denoted with f rather than ph (which would denote the
   Greek letter φ). Sulfur in Greek is theion (θεῖον).

Fire and brimstone

   Christian countries often associate sulfur, (in English usually under
   its ancient name, brimstone) with Hell and divine wrath, mostly due to
   the phrase " fire and brimstone", which occurs in the Bible in
   descriptions of Hell and divine punishment. "Fire and brimstone"
   sermons are those used by some preachers to compel belief by depictions
   of the horrors of Hell and its punishments. A joke among scientists has
   used those descriptions of Hell to conclude that, whereas Heaven's
   temperature would be a scorching 525 degrees Celsius (because it is
   bathed in a light of the sun... sevenfold as the light of seven days)
   Hell can be no hotter than the boiling point of brimstone (a mere 444.6
   degrees Celsius), and thus cannot be as hot as Heaven.

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