Sulfur Element is a non-metallic element with the chemical symbol S and an atomic number of 16. Sulfur is one of the oxygen group elements (Group VIA) and is located in the third period in the Periodic Table.

Usually elemental sulfur is a yellow crystal, also known as sulfur. There are many kinds of allotropes of sulfur simple substances, such as orthorhombic sulfur, monoclinic sulfur, and elastic sulfur. Sulfur is usually present in nature in the form of sulfides, sulfates or simple substances. Sulfur is hardly soluble in water, slightly soluble in ethanol, and easily soluble in carbon disulfide.

Sulfur Element

Sulfur is an important component of protein in the human body and is of great significance to human life activities. Sulfur is mainly used in the production of fertilizers, gunpowders, lubricants, insecticides, and antifungals.

The sulfur dioxide (SO2) produced by the combustion of sulfur and sulfur-bearing ore (S+O2 = ignition = SO2) combines with water to form sulfurous acid in the air, and sulfurous acid combines with oxygen in the air to form sulfuric acid, thereby causing acid-type acid rain.

sulfur dioxide

For the human body, natural elemental sulfur is non-toxic and harmless, while dilute sulfuric acid, sulfate, sulfurous acid, and sulfite are toxic, and sulfides are usually highly toxic. Concentrated sulfuric acid can corrode human skin.

Where is sulfur found?

Sulfur is widely distributed in nature and is contained in the earth’s crust at a concentration of 0.048% by mass. In the natural world, the existence form of sulfur has a free state and a combined state. Elemental sulfur is mainly found in the area around the volcano.

The sulfur present in the chemical state is mostly mineral and can be divided into sulfide ore and sulfate mineral. Sulfide ore is Pyrite (FeS2)Chalcopyrite (CuFeS2), 

Galena (PbS), Sphalerite (ZnS), and the like. Sulfate mines are Gypsum (CaSO4·2H2O), Thenardite (Na2SO4·10H2O), Barite (BaSO4), Celestite (SrSO4), Vermiculite [(AlO)2SO4·9H2O], Alumite [K2SO4·Al2(SO4)3·24H2O] and the like. A small amount of sulfur is usually also contained in coal.

Sulfur Properties

Physical Properties

Nuclide and Atomic (ion) Structure:

There are 25 Isotopes of sulfur, four of which are stable: 32S (95.02%), 33S (0.75%), 34S (4.21%) and 36S (0.02%), except for 35S, other radioisotopes The half-life is very short. Sulfur-35 is caused by cosmic rays that shoot argon- 40 in the air with a half-life of 87.48 days.

In forest ecosystems, sulfate is mainly from air and a small amount is derived from mineral weathering. The different levels of sulfur isotopes can be used to determine their origin.

Atomic radius: 102 pm.

Ion radius: 184 pm (S2-), 29 pm (S4+).

The ground state atomic electronic arrangement is: 1s 2 2s 2 2p 3s 2 3p 4. (Bold part is valence electron)

Molecular Species:

Sulfur elements of different molecular species include S2 (dimerized sulfur), S3 (trimeric sulfur), S4 (tetrameric sulfur), S5 (penta-sulfur), S6 (cyclohexasulfur), S7 (Hexasulfuryl), S8 (cyclooctene), S9 (cyclohexasulfenyl), S10 (cyclooctasulfenyl), S11 (cyclohexasulfenyl), S12 (cyclodulphide), S18 (Ring octadecyl sulphate, S20 (cyclo 20 sulphur) and sulfur chain.


Pure sulfur is a pale yellow solid with a soft, light texture and a stinky powder.


Sulfur is insoluble in water but soluble in carbon disulfide.

Both thermal conductivity and electrical conductivity are poor. Crunchy, insoluble in water. Amorphous sulfur is mainly composed of elastic sulfur, which is obtained by rapidly pouring molten sulfur into ice water. Unstable, can be converted to crystalline sulfur.

The crystalline sulfur is soluble in organic solvents such as carbon disulfide (while elastic sulfur can only be partially dissolved), carbon tetrachloride, toluene, and benzene.

In addition to the zero price, there are three common valences, which are -2 (hydrogen sulfide), +4 (sodium sulfite), and +6 (sulfuric acid), and the +2 (sodium formaldehyde sulfoxylate) is not common. The first ionization energy is 10.360 electron volts.


The crystalline sulfur is insoluble in water, slightly soluble in ethanol and diethyl ether, and soluble in carbon disulfide, carbon tetrachloride, toluene, and benzene. It can be converted to crystalline sulfur (orthogonal sulfur), which is the only stable form of sulfur at room temperature. Atomic radius: 88 pm.


With the different order of the S8 rings in space, several sulfur elemental crystals can be formed, the most common of which is orthorhombic sulfur and monoclinic sulfur.

The orthorhombic sulfur is also known as rhombohedral or alpha-sulfur, which is the only stable form of sulfur present at room temperature. When heated to 95.5 °C, it turns into monoclinic sulfur (it does not melt at this time).

Monoclinic sulfur, also known as beta-sulfur, slowly converts to stable orthorhombic sulfur below 95.5 °C. Both monoclinic sulfur and orthorhombic sulfur are soluble in non-polar solvents such as carbon disulfide (CS2) and benzene (C6H6).

Cell Parameters

a = 1043.7 pmb = 1284.5 pmc = 2436.9 pm
α = 90°β = 90°γ = 90°


The molecule of solid sulfur is generally S8, and its structure is saddle-shaped. When sulfur is heated, the molecular structure changes. When heated to 160 °C, the ring of S8 began to break into an open chain, the viscosity increased, and the viscosity was maximum at 190 °C. When heating is continued above 190 °C, the long chain begins to break and the viscosity drops again. At 130 to 160 °C, the viscosity of liquid sulfur is the smallest and the fluidity is the best. The viscosity of sulfur at various temperatures is shown in the figure.

Chemical Properties

Atomic Property

Affinity (kJ·mol-1): A 1 :-200, A 2 :590,

The ionization energy is shown in the following table

Ionization energy (KJ/mol)

First ionization energy: 999.6Sixth ionization energy: 8495
Second ionization energy: 2251Seventh ionization energy: 27106
Third ionization energy: 3361The eighth ionization energy: 31669
Fourth ionization energy: 4564Ninth ionization energy: 36578
Fifth ionization energy: 7013Tenth ionization energy: 43138

Electronegativity: 2.58 (Pauling scale), 2.44 (Alai-Ross Week Scale).


Sulfur element in all physical states (solid, liquid and gaseous), sulfur has different allotropes, and the relationship between these allotropes is not fully understood. The sulfur of the crystal generally constitutes a ring composed of eight atoms: S8, and there is also an unstable cyclic S6 molecule as a structural unit of sulfur. The elemental sulfur molecule is most stable in the ring S8, in which each sulfur atom adopts sp 3 inequality hybridization, and is connected to the other two sulfur atoms by a single bond, and the bond length is 206 pm. The inner key angle is 108° and the angle between the two faces is 98°. Regardless of the type, the sulfur element is often abbreviated as S.

Common Reaction

Sulfur can react with variable-valent metals to form low-valent metal sulfides such as sulfur powder and iron powder

Fe + S = FeS

Sulfur powder and copper powder

2Cu + S = Cu2S

Note: Sulfur and mercury react at room temperature:

Hg + S = HgS

Therefore, the leaked mercury can be treated with sulfur.

Sulfur element can react with strong oxidizing acids such as:

S + 2H2SO4 (concentrated) = 3SO2 + 2H2O

(Growth means thick).

Valence and the corresponding compound

The common valence of sulfur in nature is -2, 0, +4, +6.

-2 valence is H2S, Na2S, and other sulfides, 0-valent sulfur is simple substance of sulfur, +4 valence of SO2, H2SO3, sulfite (Na2SO3, etc.), +6 The valence is SO3, H2SO4, sulfate (Na2SO4, etc.).


Industrial sulfur is a flammable solid. In addition, when the air contains a certain concentration of sulfur dust, it will not only explode in case of fire, but also the sulfur dust is easily charged with static electricity to cause an explosion (the lower limit of sulfur dust explosion is 2.3g/m3, and then the fire causes a fire.

Sulfur is classified as Class B according to the risk of solid fire, and the sulfur recovery and molding device is a fire hazard Class B device. Inhalation of sulfur dust by the human body can also cause cough and sore throat.

(1) Burning explosion:

1 Under normal conditions, the burning is slow, and the burning speed increases sharply when mixed with the oxidant.

2 Mixing with an oxidant to form an explosive mixture.

3 In case of fire, high temperature is prone to fire.

4 Dust easily with up to thousands of volts or even tens of thousands of volts of static electricity.

5 High temperature and open flame caused by friction can cause sulfur dust explosion and fire.

6 Under normal circumstances, sulfur dust is more likely to explode than flammable gas, but the burning speed and explosion pressure are smaller than that of flammable gas.

(2) Harm to the human body:

1 Because it can be partially absorbed into hydrogen sulfide in the intestine and absorbed by the human body, a large amount of swallowing (10g or more) can cause hydrogen sulfide poisoning.

2 can cause conjunctivitis, skin eczema, and weak irritation to the skin.

3 Long-term inhalation of sulfur dust is generally not toxic.

Exposure limits: China MAC, US TWA, and STEL have no standards

Toxicological information: low toxicity.

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Sulfur Uses

Industrial Demand

Sulfur element is important in the industry, such as sulfuric acid in batteries or in solution. Sulfur is used to make gunpowder. Used as a vulcanizing agent in the rubber industry. Sulfur is also used to kill fungi and is used as a fertilizer.

Industrial Sulfur

Sulfides are used in the paper industry for bleaching. Sulfate is also used in fireworks. Sodium thiosulfate and ammonium thiosulfate are used as fixers and fertilizers in photography.

Production of sulfuric acid, sulfates, pesticides, plastics, enamels, synthetic dyes, rubber vulcanization, bleaching, pharmaceuticals, paints, sulfur ointments, etc.

The main use of sulfur minerals is in the production of sulphuric acid and sulfur. Sulfuric acid is a major sulfur-consuming household, and about 70% of China’s sulfur is used in sulfuric acid production. Fertilizer is the largest household of sulfuric acid, and its consumption accounts for more than 70% of total sulfuric acid. In particular, phosphate fertilizer consumes the most sulfuric acid and the largest increase.

Chemical fertilizers except for the sulfuric acid, but also for the production of phenol, potassium and other 90 kinds of chemical products; metallurgical; a bicycle light system, leather industry; textile adhesive system, fibers, Vinylon products steel acid Washing and fluoride salt production sectors; petroleum systems for crude oil processing, petroleum catalysts, additives, and pharmaceutical industries are all inseparable from sulfuric acid.

High-grade pyrite cinder can recover iron, etc.; low-grade cinder can be used as cement ingredients. The slag can also recover a small amount of silver, gold, copper, aluminum, zinc, and cobalt. In addition to the raw materials for the production of sulfuric acid, sulfur is also widely used in the production of chemical products such as copper sulfide and sodium metabisulfite. In addition, in sugar production, sulfur is oxidized to sulfur dioxide gas for bleaching and decolorization.

Sulfur is used to make black powder, matches, etc. Sulfur is also an important raw material for the production of rubber products. Sulfur is also used to kill fungi and is used as a fertilizer. Sulfides are used in the paper industry for bleaching. Thiosulfate, sodium thiosulfate and ammonium sulfate make the photographic fixer. Sulfur is also a raw material for the manufacture of certain pesticides such as lime sulfur mixture.

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Physiological action

Amino acids such as cysteine, methionine, homocysteine ​​and taurine and some common enzymes contain sulfur, so the sulfur element is an essential element in all cells. In proteins, disulfide bonds between polypeptides are an important part of protein construction.

Some bacteria use hydrogen sulfide as an electron supply in some photosynthesis-like processes (generally plants use water to do this). Plants absorb sulfur in the form of sulfates. Inorganic sulfur is an integral part of the iron-sulfur protein. In cytochrome oxidase, the sulfur is a key component.

In medical treatment, sulfur can also be used to make Sulphur ointment to treat certain skin diseases, but sulfur is harmful to the body. Long-term work under high-sulfur industrial and mining has great damage to the body.

In daily life, the mercury thermometer ruptures and can be sprinkled with sulfur on the scattered mercury beads to form a stable compound Hg + S = HgS to prevent mercury evaporation hazards.

Defense Measures

According to the national standard “Industrial Sulfur” (GB 2449-2006), the protection of industrial sulfur safety and other matters are as follows.

  • Safety

Workers engaged in the production, transportation, storage, and processing of industrial sulfur should use the necessary protective equipment when operating.

Strictly abide by the national safety regulations on fire protection and dangerous goods. Special fire-fighting equipment shall be installed in industrial sulfur storage sites and warehouses, and open flames are strictly forbidden. It is allowed to extinguish the burnt sulfur by spraying water or the like.

Since sulfur dust is explosive, the use and transportation of industrial sulfur should prevent the formation or release of sulfur dust. The production, storage, and use of liquid sulfur are carried out in accordance with relevant safety regulations.

  • Marking, packaging, transportation, and storage

There should be obvious and firm signs on the packaging container of industrial sulfur, including the name of the manufacturer, the address of the factory, the name of the product, the trademark, the grade, the net quality, the batch number, the date of manufacture, the standard number of “Industrial Sulfur” and the requirements of GB 190. Flammable solids” sign.

Solid products can be packaged in plastic woven bags or lined plastic film bags, or in bulk. Among them, the packaged sulfur may not be lined with a plastic film bag, and the bulk product should be covered, but the powdered sulfur cannot be bulk. Liquid sulfur should be stored in a special container.

The transportation of products shall be carried out in accordance with relevant state regulations.

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Bulk, granular sulfur can be stored in the open air or in the warehouse. Powdered, flaked sulfur is stored in a covered location or warehouse.

The bagged products are piled up in piles, and there should be no less than 0.75m wide passage between the stacks. Do not place near water and sewage pipes and heating equipment.