Sulfur
A common component of the periodic table, sulfur gives off a pungent smell of spoiled eggs. Despite the odor, it has been used for medical purposes for centuries due to its antibacterial, antifungal and keratolytic properties. Formerly, it was a popular remedy for skin conditions like acne, rosacea, and seborrheic dermatitis, however, due to its scent, its usage lessened.
The exact mechanism of sulfur’s action is not known, but its effect is dependent on the size of its particles. The United States Pharmacopeia lists two varieties of sulfur – sublimed and precipitated. The latter has smaller particles and is a better quality.
Sulfur is also known to work in conjunction with other substances used to treat acne, such as salicylic acid and sodium sulfacetamide. In particular, the combination of 10% sodium sulfacetamide and 3% sulfur has been shown to be helpful in treating acne.
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature.
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| Sulfur | |||||||||||||||||||||||||||||||
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| Alternative name | sulphur (British spelling) | ||||||||||||||||||||||||||||||
| Allotropes | see Allotropes of sulfur | ||||||||||||||||||||||||||||||
| Appearance | lemon yellow sintered microcrystals | ||||||||||||||||||||||||||||||
| Standard atomic weight Ar°(S) |
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| Sulfur in the periodic table | |||||||||||||||||||||||||||||||
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| Atomic number (Z) | 16 | ||||||||||||||||||||||||||||||
| Group | group 16 (chalcogens) | ||||||||||||||||||||||||||||||
| Period | period 3 | ||||||||||||||||||||||||||||||
| Block | p-block | ||||||||||||||||||||||||||||||
| Electron configuration | [Ne] 3s2 3p4 | ||||||||||||||||||||||||||||||
| Electrons per shell | 2, 8, 6 | ||||||||||||||||||||||||||||||
| Physical properties | |||||||||||||||||||||||||||||||
| Phase at STP | solid | ||||||||||||||||||||||||||||||
| Melting point | 388.36 K (115.21 °C, 239.38 °F) | ||||||||||||||||||||||||||||||
| Boiling point | 717.8 K (444.6 °C, 832.3 °F) | ||||||||||||||||||||||||||||||
| Density (near r.t.) | alpha: 2.07 g/cm3 beta: 1.96 g/cm3 gamma: 1.92 g/cm3 | ||||||||||||||||||||||||||||||
| when liquid (at m.p.) | 1.819 g/cm3 | ||||||||||||||||||||||||||||||
| Critical point | 1314 K, 20.7 MPa | ||||||||||||||||||||||||||||||
| Heat of fusion | mono: 1.727 kJ/mol | ||||||||||||||||||||||||||||||
| Heat of vaporization | mono: 45 kJ/mol | ||||||||||||||||||||||||||||||
| Molar heat capacity | 22.75 J/(mol·K) | ||||||||||||||||||||||||||||||
Vapor pressure
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| Atomic properties | |||||||||||||||||||||||||||||||
| Oxidation states | −2, −1, 0, +1, +2, +3, +4, +5, +6 (a strongly acidic oxide) | ||||||||||||||||||||||||||||||
| Electronegativity | Pauling scale: 2.58 | ||||||||||||||||||||||||||||||
| Ionization energies |
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| Covalent radius | 105±3 pm | ||||||||||||||||||||||||||||||
| Van der Waals radius | 180 pm | ||||||||||||||||||||||||||||||
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| Other properties | |||||||||||||||||||||||||||||||
| Natural occurrence | primordial | ||||||||||||||||||||||||||||||
| Crystal structure | orthorhombic | ||||||||||||||||||||||||||||||
| Thermal conductivity | 0.205 W/(m⋅K) (amorphous) | ||||||||||||||||||||||||||||||
| Electrical resistivity | 2×1015 Ω⋅m (at 20 °C) (amorphous) | ||||||||||||||||||||||||||||||
| Magnetic ordering | diamagnetic | ||||||||||||||||||||||||||||||
| Molar magnetic susceptibility | (α) −15.5×10−6 cm3/mol (298 K) | ||||||||||||||||||||||||||||||
| Bulk modulus | 7.7 GPa | ||||||||||||||||||||||||||||||
| Mohs hardness | 2.0 | ||||||||||||||||||||||||||||||
| CAS Number | 7704-34-9 | ||||||||||||||||||||||||||||||
| History | |||||||||||||||||||||||||||||||
| Discovery | before 2000 BCE | ||||||||||||||||||||||||||||||
| Recognized as an element by | Antoine Lavoisier (1777) | ||||||||||||||||||||||||||||||
| Main isotopes of sulfur | |||||||||||||||||||||||||||||||
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Sulfur is the tenth most abundant element by mass in the universe and the fifth most on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. Sulfur is used in matches, insecticides, and fungicides. Many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes.
Sulfur is an essential element for all life, but almost always in the form of organosulfur compounds or metal sulfides. Amino acids (two proteinogenic: cysteine and methionine, and many other non-coded: cystine, taurine, etc.) and two vitamins (biotin and thiamine) are organosulfur compounds crucial for life. Many cofactors also contain sulfur, including glutathione, and iron–sulfur proteins. Disulfides, S–S bonds, confer mechanical strength and insolubility of the (among others) protein keratin, found in outer skin, hair, and feathers. Sulfur is one of the core chemical elements needed for biochemical functioning and is an elemental macronutrient for all living organisms.
