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About Sulphur: the technical stuff
 

Sulphur: Symbol S. A yellow non-metallic element belonging to group 16 (formerly VIB) of the periodic table. a.n.16; r.a.m.32.06. r.d. 2.07 (rhombic); m.p. 112.8C. b.p.444.614C.

The element occurs in many sulphide and sulphate minerals and native sulphur is also found in Sicily and the USA (obtained through the Frasch process). It can also be obtained from hydrogen sulphide by the Claus process.

Sulphur has various allotropic forms. Below 95.6C the stable crystal form is rhombic: above this temperature the element transforms into a triclinic form. These crystalline forms both contain S8 molecules, At temperatures just above the melting point, molten sulphur is a yellow liquid containing S8 rings (as in the solid form). At about 160C the sulphur atoms form chains and the liquid becomes viscous and dark brown. If the molten sulphur is cooled quickly from this temperature (e.g. by pouring into cold water) a reddish brown solid known as plastic sulphur is obtained. Above 200C the viscosity decreases. Sulphur vapour contains a mixture of S2 S4 S6 and S8 molecules.

The element is also used to produce sulphuric acids and other sulphur compounds

Flowers of sulphur is a yellow powder obtained by subliming the vapour (sublimation: a direct change of state from solid to gas to solid). It is used in a range of products from garden fungicides to dandruff control shampoos, in pharmaceutical, agricultural, horticultural, animal health and homeopathy industries.

Sulphur is an essential element in living organisms and sulphur is absorbed by plants from the soil as the sulphate (SO42-). Essential elements are those elements required by living organisms to ensure normal growth, development and maintenance. Apart from the elements found in organic compounds (i.e. carbon, hydrogen, oxygen, and nitrogen) plants, animals and micro-organisms all require a range of elements in varying amounts depending on the type of organism. The major elements present in the tissues in relatively large amounts (greater than 0.005%) are calcium, phosphorus, potassium, sodium, chlorine, sulphur and magnesium. Trace elements occur at much lower concentrations and thus requirements are much less. The most important are iron, manganese, zinc, copper, iodine, cobalt, selenium, chromium and silicon. Each element may fulfil one or more of a variety of metabolic roles.  

Group 16 is a group of elements in the periodic table: oxygen (O) sulphur (S) selenium (Se) tellurium (Te) and polonium (Po), which all have outer electron configurations ns2np4 with no partly filled inner levels. They are also called the chalcogens. (Formerly they were classified in group VI which consisted of subgroups VIA and VIB).

Sulphur cycle: the cycling of sulphur between the biotic (living) and the abiotic (nonliving) components of the environment. Most of the sulphur in the abiotic environment is found in rocks, although a small amount is present in the atmosphere as sulphur dioxide (SO2) produced by combustion of fossil fuels. Sulphates (SO42-) derived from the weathering and oxidation of rocks is taken up by plants and incorporated into sulphur containing proteins and passed along the food chain to animals, Decomposition of dead organic matter by anaerobic sulphate reducing bacteria returns sulphur to the abiotic environment in the form of hydrogen sulphide (H2S). Hydrogen sulphide can be converted back to sulphate or to elemental sulphur by the action of different groups of photosynthetic and sulphur- reducing bacteria. Elemental sulphur becomes incorporated into rocks.

Sulphate: a salt or ester of sulphur (VI) acid. Organic sulphates have the formula R2SO4 where R is the organic group. Sulphate salts contain the ion SO42-.

Sulphite: a salt or ester derived from sulphurous acid. The salts contain the ion SO32-. Sulphites generally have reducing properties.

Sulphides:   

1 Inorganic compounds of sulphur with more electropositive elements. Compounds of sulphur with non metals are covalent compounds e.g. hydrogen sulphide H2S

2 Organic compounds that contain the group S linked to two hydrocarbon groups.

Yet more about Sulphur

Sulphur is found in group 16 of the periodic table . It exhibits allotropy . Solid sulphur occurs principally in three forms, all of which are brittle, yellow in colour, odourless, tasteless, and insoluble in water. Two of these solid forms are crystalline, composed of molecules containing eight sulphur atoms and having molecular weight 256.512 amu. Rhombic sulphur has orthorhombic crystalline structure and is stable below 95.5C; most sulphur is in this form. The monoclinic, or prismatic, form has long, needle-like, nearly transparent crystals; it is stable between 95.5C and its melting point but reverts to the rhombic form on standing at room temperature. Amorphous sulphur is a dark, non-crystalline, gum-like substance. It is often thought to be a super-cooled liquid. It is formed by rapidly cooling molten sulphur, e.g., by pouring it into cold water. It slowly reverts to the rhombic form on standing.

Sulphur , non-metallic chemical element; symbol S; at. no. 16; at. wt. 32.06; m.p. 112.8C (rhombic), 119.0C (monoclinic), about 120C (amorphous); b.p. 444.674C; sp. gr. at 20C, 2.07 (rhombic), 1.957 (monoclinic), 1.92 (amorphous);

Even more about sulphur:

The following is a very useful round up of various online definitions of sulphur and its uses

http://www.answers.com/topic/sulfur

The following gives a simple summary of sulphur and flowers

http://www.sulphurinstitute.org/learnmore/glossary.cfm

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