Quick Facts
| Property | Value |
|---|---|
| Symbol | S |
| Atomic Number | 16 |
| Atomic Mass | 32.06 u |
| Category | Nonmetal |
| Period | 3 |
| Group | 16 |
| Block | p |
| Electron Configuration | [Ne] 3s² 3p⁴ |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 2.07 g/cm³ |
| Melting Point | 115.21°C (388.36 K) |
| Boiling Point | 444.61°C (717.76 K) |
| Appearance | Yellow crystalline solid |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Ne] 3s² 3p⁴ |
| Electronegativity | 2.58 (Pauling scale) |
| First Ionization Energy | 999.6 kJ/mol |
| Atomic Radius | 104 pm |
| Covalent Radius | 105 pm |
| Van der Waals Radius | 180 pm |
History and Discovery
Discovered by: Known since antiquity Year of Discovery: Ancient Location: Various
Etymology
The name "sulfur" (or "sulphur" in British English) comes from the Latin "sulpur" or "sulfur," which may derive from Sanskrit "sulvere" or Arabic "sufra" meaning yellow.
Discovery Story
Sulfur has been known since ancient times and is mentioned in the Bible as "brimstone." Ancient peoples used it for fumigation, medicine, and bleaching. Antoine Lavoisier recognized it as an element in 1777. It was one of the few elements known in antiquity due to its occurrence in native (elemental) form near volcanic areas.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ³²S | 94.93% | Stable | - |
| ³³S | 0.76% | Stable | - |
| ³⁴S | 4.29% | Stable | - |
| ³⁶S | 0.02% | Stable | - |
Occurrence
Natural Abundance
Sulfur is the 10th most abundant element in the universe and comprises about 350 ppm of Earth's crust. It occurs in native form near volcanic regions and hot springs. Major sources include sulfide ores (pyrite, galena, sphalerite), sulfate minerals (gypsum), and natural gas/petroleum (as hydrogen sulfide).
Extraction and Production
- Frasch Process: Mining native sulfur from underground deposits (historical)
- Claus Process: Recovering sulfur from natural gas and petroleum refining
- Sources: Primarily petroleum and natural gas processing
- Global production: about 80 million tons annually
Applications and Uses
Chemical Industry
- Sulfuric acid production (most produced chemical worldwide)
- Vulcanization of rubber
- Sulfite production for paper bleaching
- Dye and pigment manufacturing
Agricultural Applications
- Fertilizers (sulfur is essential for plants)
- Fungicides and pesticides
- Soil amendments
Industrial Applications
- Petroleum refining
- Metal processing
- Match production
- Black gunpowder
Other Uses
- Pharmaceuticals (sulfonamide antibiotics)
- Wine preservation (sulfites)
- Skin treatments (acne, eczema)
Biological Role
Sulfur is essential for life. It is found in the amino acids cysteine and methionine, and in vitamins like biotin and thiamine.
In the Human Body
- About 0.25% of body mass (175 g in adult)
- Found in proteins (cysteine, methionine)
- Important for enzyme function
- Component of cartilage and connective tissue
- Daily requirement: about 850 mg (from protein)
Dietary Sources
Protein-rich foods provide sulfur: eggs, meat, fish, dairy, legumes, garlic, onions, and cruciferous vegetables.
Safety and Hazards
Toxicity
Elemental sulfur has low toxicity. However, hydrogen sulfide (H₂S) is extremely toxic. Sulfur dioxide (SO₂) irritates the respiratory system.
Handling Precautions
- Molten sulfur can cause severe burns
- Sulfur dust can ignite and explode
- Hydrogen sulfide is lethal at high concentrations
- Use respiratory protection for dust exposure
- Sulfur fires produce toxic SO₂
Environmental Impact
Sulfur dioxide from burning fossil fuels causes acid rain. Sulfur emissions are regulated worldwide. Natural sulfur is environmentally benign.
Interesting Facts
- Sulfur is often called "brimstone" from the Old English "brynstan" meaning "burning stone"
- The distinct smell of rotten eggs is hydrogen sulfide, not elemental sulfur
- Vulcanized rubber (with sulfur) was invented by Charles Goodyear in 1839
- More sulfuric acid is produced annually than any other industrial chemical
- Sulfur bacteria can live in extreme environments like hot springs and deep-sea vents