|
|
Atomic Number: |
16 |
Melting Point: | 119.6 ºC | |
| Atomic Symbol: | S | Boiling Point: | 444.60 ºC | ||
| Atomic Weight: | 32.06 amu | Density: | 1960
kg/m 3 |
||
| Atomic Radius: |
104 pm |
Oxidation States: | 6, 4, 2, -2 | ||
| Covalent Radius: | 102 pm | Electron Configuration: | [Ne]3s23p4 | ||
| van der Waals Radius: |
180 pm |
State of Matter: | solid |
(Sanskrit, sulvere; L. sulpur) Sulfur was known in ancient times and was called brimstone in the Biblical story of Genesis.
Sulfur is pale yellow, odorless, brittle solid, which is insoluble in water but soluble in carbon disulfide. In every state, whether gas, liquid or solid, elemental sulfur occurs in more than one allotropic form or modification; these present a confusing multitude of forms whose relations are not yet fully understood.
In 1975, University of Pennsylvania scientists reported synthesis of polymeric sulfur nitride, which has the properties of a metal, although it contains no metal atoms. The material has unusual optical and electrical properties.
High-purity sulfur is commercially available in purities of 99.999+%.
Amorphous or "plastic" sulfur is obtained by fast cooling of the crystalline form. X-ray studies indicate that amorphous sulfur may have a helical structure with eight atoms per spiral. Crystalline sulfur seems to be made of rings, each containing eight sulfur atoms, which fit together to give a normal X-ray pattern.
Sulfur is found in meteorites. R.W. Wood suggests that the dark area near the crater Aristarchus is a sulfur deposit.
Sulfur occurs native in the vicinity of volcanos and hot springs. It is widely distributed in nature as iron pyrites, galena, sphalerite, cinnabar, stibnite, gypsum, epsom salts, celestite, barite, etc.
It is commercially recovered from wells sunk into the salt domes along the Gulf Coast of the U.S. Using the Frasch process heated water is forced into the wells to melt the sulfur, which is then brought to the surface.
Sulfur also occurs in natural gas and petroleum crudes and must be removed from these products. Formerly this was done chemically, which wasted the sulfur; new processes now permit recovery. Large amounts of sulfur are being recovered from Alberta gas fields.
Sulfur is a component of black gunpowder, and is used in the vulcanization of natural rubber and a fungicide. It is also used extensively in making phosphate fertilizers. A tremendous tonnage is used to produce sulfuric acid, the most important manufactured chemical. It is used to make sulfite paper and other papers, to fumigate fumigant, and to bleach dried fruits. The element is a good insulator. It is used in the production of batteries, detergents, matches and fireworks.
Sulfur is essential to life. It is a minor constituent of fats, body fluids, and skeletal minerals. The amino acids cysteine, methionine, homocysteine, and taurine contain sulfur, as do some common enzymes.
Organic compounds containing sulfur are very important. Calcium sulfur, ammonium sulfate, carbon disulfide, sulfur dioxide, and hydrogen sulfide are but a few of the many important compounds of sulfur. Sodium or ammonium thiosulfate are used as photographic fixing agents. Epsom salts, magnesium sulfate, can be used as a laxative, as a bath additive, as an exfoliant, or a magnesium supplement in plant nutrition.
The massive burning of coal by industry and power plants liberates huge amounts of sulfur dioxide, which reacts with atmospheric water and oxygen to produce sulfurice acid. By changing the pH of soil and freshwater bodies, the resulting acid rain has led to substantial damage to the natural environment in some regions.
Sulfur has 18 isotopes, of which four are stable. Other than 35S, the radioactive isotopes of sulfur are all short lived.
In most forest ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporates also contributes 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 hydologic studies. Differences in the natural abundances can also be used in systems where there is sufficient variation in the S-34 of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different dS-34 values from lakes believed to be dominated by watershed sources of sulfate.
Carbon disulfide, hydrogen sulfide, and sulfur dioxide should be handled carefully.
Although sulfur dioxide is sufficiently safe to be used as a food additive in small amounts, in higher atmospheric concentration it reacts with water in the lungs to form sulfurous acid there; this causes immediate bleeding, the lungs fill up with blood and suffocation results. In creatures without lungs such as insects or plants, it otherwise prevents respiration.
In small concentrations hydrogen sulfide can be metabolized. However, it is quite toxic, even more toxic than cyanide. Although very smelly at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. Higher concentrations can quickly cause death by respiratory paralysis.
