Sulfur

Sulfur in Periodic Table

Sulfur (atomic number 16 and symbol S) is a non-metal or group 16 element in the periodic table found mostly in hot springs and volcanoes. It is a member of the chalcogens that contain other members, oxygen, selenium, and tellurium. The electronic configuration of sulfur is [Ne] 3s²3p⁴. Therefore, it is placed in group 16 and period 3 in the modern periodic table. Sulfur is essential to all living things, such as plants and animals. It is an important nutrient for plants, and it is used to make two of the essential amino acids needed to make proteins.

Sulfur element in Periodic Table

Such a group 16 element occurs in nature in the molecular form and also in a combined state. Galena, iron pyrite, sphalerite, stibnite, cinnabar, Epsom salts, gypsum, celestite, and barite are the most common minerals that contain a requisite amount of sulfur. It is also found in petroleum crude oil, and natural gas.

Sulfur Extraction

There are huge deposits of native sulfur found below the surface under the layer of clay and limestone in Texas and Louisiana (USA). Commercially, sulfur can be extracted by the Frasch process.

Frasch Process

In the Frasch process, native sulfur can be extracted by digging holes from the surface down to the bed of sulfur. After that, three concentric pipes can be lowered into the sulfur bed.

Steam at a temperature of 160°C and under pressure can be introduced through the outermost tube. Simultaneously, a blast of hot air under high pressure is blown through the innermost pipe. The sulfur melts, and a frothy mixture of sulfur, air, and water moves up the second annular space between the pipes. The mixture was then collected, and sulfur was further purified by distillation.

From Sulfur Compounds

Economically, sulfur can be extracted from the sulfur dioxide liberated during the roasting of metal sulfides. When sulfur dioxide passed over hot coke at 1100°C, it was reduced to form sulfur.

Industrially, sulfur is now recovered from natural gas that contains about 20% hydrogen sulfide. The liberated hydrogen sulfide gas is first absorbed in ethanolamine. Thereafter, the gas can be recovered, and one third of it is burned to give sulfur dioxide, sulfur, and water vapour. The sulfurdioxe botained by this process then reacts with the remaining hydrogen sulfide in the presence of Fe₂O₃/Al₂O₃ to produce sulfur vapour.

Properties

The atomic number of such a non-metal is 16, with an atomic weight of 32.066. Such a group 16 element has been known since prehistoric times. The name sulfur originated from the Latin name sulphurium and the Sanskrit name sulvere.

Sulfur is a pale yellow, brittle, odorless solid with a melting point of 112.8°C (rhombic) or 119.0°C (monoclinic) and a boiling point of 444.674°C. Such an allotropic non-metal is insoluble in water but soluble in carbon disulfide.

• Symbol: S
• Atomic number: 16
• Relative atomic mass: 32.06
• Electronic Configuration: [Ne]3s²3p⁴
• Periodic position: Placed in Group 16 and period 3
• Discovery: Known from prehistoric times.
• Origin of the name: The name originates from the Sanskrit name ‘sulvere’ and the Latin name ‘sulfurium’.
• Common Allotropes: The most common allotropes are α-S (orthorhombic), β-S (monoclinic), S2, S3, cyclo-S8
• Appearance at 20°C: tasteless, odorless, yellow, brittle solid
• Melting Point: 115.21°C
• Boiling Point: 444.61°C
• Density (g/cm³): 2.070
• Atomic radius (non-bonded): 1.80Å
• Covalent radius: 1.04Å
• Electron affinity: 200.41 kJ/mol
• Electronegativity (Pauling scale): 2.58
• 1st ionization energy: 999.589 kJ/mol
• Oxidation States: 6, 4, 2, -2
• CAS Registry Number: 7704–34–9

Chemical Properties

The outermost quantum shell of chalcogens consists of an s2p4 electronic configuration. Oxygen among the chalcogens does not possess any d-orbital since its n=2 quantum shell does not possess any d-orbital. Therefore, it cannot expand its valence shell beyond an octet. However, other elements, specifically sulfur of this group, can use their vacant d-orbitals for bonding to give valences 2, 4, 6.

When we move down in the chalcogen group, the metallic character can increses due to a decrease in ionization energy. Therefore, oxygen and sulfur is an in insulators, selenium and tellurium are semiconductors, and polonium is a metal.

Allotropic Modifications

Sulfur has the most varied range of allotropic modifications. Catenation of sulfur is quite pronounced, but it can adopt varied arrangements within the crystal. The allotropic forms are very sensitive to variation in temperature.

• The most common allotropic form of such a group 16 element is the yellow rhombic sulfur. The usual roll sulfur, sublimed flower of sulfur, and precipitated milk of sulfur belong to the rhombic form.
• It has a puckered cyclo-S8 ring, and when the temperature rose to about 95°C, it changed to monoclinic sulfur. The S8 ring still persists, although the packing becomes disordered.
• Monoclinic S8 is obtained when ordinary sulfur heating about 100°C and then cooled rapidly to room temperature.
• Sudden cooling of liquid sulfur from 160°C or dropping such liquid into water gives plastic sulfur. Such variety can be converted into fibers. It is insoluble in organic solvents and slowly returns to the crystalline rhombic form.
• The S8 units still persist above the boiling point of sulfur. When the temperature increses, the S8 units dissociate successively into S6, S4, and S2.
• The S6 ring has the chair conformation. Many other cyclic forms, such as cyclo-S7, S10, S12, S18, and S20, have been synthesized.

Uses of Sulfur

Sulfur has been known and used since prehistoric times. Historically, sulfur, also called brimstone, was crucial in Egypt, Greece, Rome, and China for fumigation, medicine, bleaching agent, preserving wine, alchemy, Greek Fire, etc. Sulfur is an essential element or nutrient for plants, and it can kill insects, mites, fungi, and rodents. The organic compounds of sulfur can be used in many fields of science. The most common uses of sulfur are:

• Sulfur is used as a component for making matches, black gunpowder, and fireworks.
• The majority of it is used for the manufacture of sulfuric acid.
• It is also used for the vulcanization of black rubber.
• It can be used to synthesize other compounds, such as carbon disulfide (CS2), sulfur dyestuffs, etc.
• Sulfur itself and sulfites can be used in the manufacture of fungicides, fumigants, and fertilizers.
• It is an insulator and is used as an electrical insulator.
• Several types of bleaching agents and paper can be made by sulfites of such a group 16 element.

The group 16 element sulfur plays an important role in living organisms, but carbon disulfide, hydrogen sulfide, and sulfur dioxide are highly toxic to humans and our environment. For example, a small amount of hydrogen sulfide can be metabolized by the human digestive system, but higher concentrations and deadens the sense of smell can cause death due to respiratory paralysis.

Facts about Sulfur

• Pure sulfur has no smell, but its many compounds have a strong and deaden smell.
• The name bimstone was known from historic times, and its meaning is “burning stone”.
• Molten sulfur is red but burns with a blue flame in a flame test. The group 16 element sulfur is the seventeenth most common element in the Earth’s crust.
• Sulfur is an essential element for the human body and the eighth most common element in the human body. Therefore, humans consume about 1 gram a day to make proteins.
• Seawater contains a huge amount of sulfur, and it is the sixth most common element.
• Gunpowder contains sulfur along with carbon and saltpeter. The compound sulfur dioxide is a major pollutant for our environment and causes acid rain.

References

• Sulfur — Element, Facts, Properties, Production, Uses — Priyamstudycentre.com
• Sulfur — Element information, properties and uses — rsc.org
• Sulfur — wikipedia.org
• Sulfur — Periodic Table of Elements — lanl.gov