![]() ![]() ![]() The second, fourth and sixth ionization energies of sulfur are 2252 kJ/mol, 4556 kJ/mol and 8495.8 kJ/mol, respectively. The reaction involves adsorption of protons onto SĨ clusters, followed by disproportionation into the reaction products. Under normal conditions, sulfur hydrolyzes very slowly to mainly form hydrogen sulfide and sulfuric acid: Sulfur is insoluble in water but soluble in carbon disulfide and, to a lesser extent, in other nonpolar organic solvents, such as benzene and toluene. The density of sulfur is about 2 g/cm 3, depending on the allotrope all of the stable allotropes are excellent electrical insulators. Molten sulfur assumes a dark red color above 200 ☌ (392 ☏). At higher temperatures, the viscosity decreases as depolymerization occurs. Between its melting and boiling temperatures, octasulfur changes its allotrope again, turning from β-octasulfur to γ-sulfur, again accompanied by a lower density but increased viscosity due to the formation of polymers. The structure of the S 8 ring is virtually unchanged by this phase change, which affects the intermolecular interactions. At 95.2 ☌ (203.4 ☏), below its melting temperature, cyclo-octasulfur changes from α-octasulfur to the β- polymorph. Octasulfur is a soft, bright-yellow solid that is odorless, but impure samples have an odor similar to that of matches. The point group of cyclo-S 8 is D 4d and its dipole moment is 0 D. The best-known allotrope is octasulfur, cyclo-S 8. Sulfur forms several polyatomic molecules. Sulfur is one of the core chemical elements needed for biochemical functioning and is an elemental macronutrient for all living organisms.Ĭharacteristics As a solid, sulfur is a characteristic lemon yellow when burned, sulfur melts into a blood-red liquid and emits a blue flame. Disulfides, S–S bonds, confer mechanical strength and insolubility of the (among others) protein keratin, found in outer skin, hair, and feathers. Many cofactors also contain sulfur, including glutathione, and iron–sulfur proteins. 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. Sulfur is an essential element for all life, but almost always in the form of organosulfur compounds or metal sulfides. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes. ![]() Many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Sulfur is used in matches, insecticides, and fungicides. The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. Historically and in literature sulfur is also called brimstone, which means "burning stone". 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. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Sulfur is the tenth most abundant element by mass in the universe and the fifth most on Earth. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S 8. It is abundant, multivalent and nonmetallic. Sulfur (also spelled sulphur in British English) is a chemical element with the symbol S and atomic number 16. ![]()
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