Nepedia
Back to Discover
Advanced Reader
⚛️

Sulfur

physical science Maturity 11-13 Next article →

Sulfur is a versatile chemical element with the symbol S and atomic number 16.

Burning-sulfur
Burning-sulfur

It is an abundant, nonmetallic, and multivalent element. In the vastness of space, sulfur ranks as the tenth most abundant element by mass. On Earth, it is even more common, ranking as the fifth most abundant element. It is an essential macronutrient for all living organisms. Without sulfur, the biochemical functions required for life could not occur.

Cyclooctasulfur-above-3D-balls
Cyclooctasulfur-above-3D-balls

At the molecular level, sulfur atoms typically form cyclic molecules. The most common form is octasulfur, which is a ring of eight atoms known as cyclo-S8.

Cyclooctasulfur-above-3D-balls
Cyclooctasulfur-above-3D-balls

This molecule has a specific structure called a D4d point group. When sulfur is in its solid state at room temperature, it is a bright lemon-yellow crystalline substance. As temperature changes, sulfur undergoes several physical transformations. When heated, it melts into a blood-red liquid. If it is burned, it produces a distinct blue flame. Between its melting and boiling points, the substance changes its allotrope, or its physical form. It transitions from beta-octasulfur to gamma-sulfur. This change increases the liquid's viscosity, which is its thickness, because long polymer chains form. At even higher temperatures, these chains break apart through a process called depolymerization.

Sulfur is famous for having many different physical forms, called allotropes. In fact, it forms over 30 different solid allotropes, which is more than any other element. Besides the standard S8 ring, other rings like S7, S6, S12, and S18 exist. A unique form called plastic sulfur can be created by cooling molten sulfur very rapidly. For example, pouring molten sulfur into cold water creates this amorphous, brownish substance. It has a helical structure and feels elastic, much like crude rubber. However, this form is metastable, meaning it is not permanent. Over hours or days, it gradually reverts to a hard, crystalline state.

Humans have interacted with sulfur since ancient history. It was used in ancient India, China, Greece, and Egypt. In historical literature, it was often called brimstone, which translates to "burning stone." While it can be found in its pure, native form, most modern sulfur is a byproduct. We obtain it by removing sulfur-containing contaminants from petroleum and natural gas.

Nearly exhausted sulphur vat from which railroad cars are loaded, Freeport Sulphur Co., Hoskins Mound, Texas, 1a35438v
Nearly exhausted sulphur vat from which railroad cars are loaded, Freeport Sulphur Co., Hoskins Mound, Texas, 1a35438v

This industrial process provides the massive amounts needed for global commerce.

Today, the most significant commercial use of sulfur is the production of sulfuric acid. This acid is vital for making phosphate and sulfate fertilizers. Sulfur is also used in the manufacturing of matches, insecticides, and fungicides.

Sulfuric acid 2000
Sulfuric acid 2000

Many sulfur compounds are known for their strong odors. For instance, hydrogen sulfide is responsible for the smell of rotting eggs. Other organosulfur compounds create the scents of garlic, grapefruit, and even skunk spray.

Menambang Belerang
Menambang Belerang

Sulfur plays a fundamental role in the biology of all living things. It is a key component of several amino acids, such as cysteine and methionine. These are the building blocks used to create proteins. Two essential vitamins, biotin and thiamine, also contain sulfur. In the human body, sulfur provides mechanical strength to proteins like keratin.

Disulfide-bridges-made-in-Avogadro
Disulfide-bridges-made-in-Avogadro

Keratin is the protein found in your hair, skin, and feathers. It stays strong and insoluble because of special chemical links called disulfide bonds (S–S bonds).

Scientists also use sulfur to understand the history of our planet and the universe. Sulfur has 23 known isotopes, including four stable ones: 32S, 33S, 34S, and 36S. The most common, 32S, is created in exploding stars through the alpha process. By measuring the ratio of these isotopes, researchers can determine the chemical history of rocks. They can estimate the temperature of ancient environments or identify the activity of bacteria in old sediments. This helps us understand the redox conditions, or oxygen levels, of ancient oceans. Even in space, sulfur is a major player. It creates the bright yellow and orange colors seen on Jupiter's moon, Io.

Io highest resolution true color
Io highest resolution true color

Recently, in July 2024, the Curiosity rover discovered elemental sulfur crystals inside a rock on Mars.

657 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (19)
File:Burning-sulfur.png
Burning-sulfur.png
File:Cyclooctasulfur-above-3D-balls.png
Cyclooctasulfur-above-3D-balls.png
File:Nearly exhausted sulphur vat from which railroad cars are loaded, Freeport Sulphur Co., Hoskins Mound, Texas, 1a35438v.jpg
Nearly exhausted sulphur vat from which...
File:Io highest resolution true color.jpg
Io highest resolution true color.jpg
File:Menambang_Belerang.jpg
Menambang_Belerang.jpg
File:Kawah Ijen -East Java -Indonesia -sulphur-31July2009.jpg
Kawah Ijen -East Java -Indonesia...
File:Lapis lazuli block.jpg
Lapis lazuli block.jpg
File:S@CNT.jpg
S@CNT.jpg
File:MODOAzufre.jpg
MODOAzufre.jpg
File:18810703 Sulphur Soap - advertisement in The Helena Independent.png
18810703 Sulphur Soap - advertisement in...
File:Soufre extraction 1.jpg
Soufre extraction 1.jpg
File:Bergelut dengan asap nan beracun.jpg
Bergelut dengan asap nan beracun.jpg

+ 7 more

More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.