Sulfur Element Properties
Complete reference for Sulfur (S, element 16): atomic data, electron configuration with interactive orbital diagram, isotopes, physical constants with temperature toggle, and key industrial uses.
Sulfur
Nonmetal — Period 3, Group 16
Atomic Identity
Electron Configuration
Two unpaired 3p electrons — triplet ground state (³P₂)
Physical Properties
Values shown for rhombic (alpha) sulfur at standard conditions unless noted.
Key Isotopes of Sulfur
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Notes |
|---|---|---|---|---|---|---|
| Sulfur-32 | ³²S | 16 | 16 | 31.97207 | 94.99% |
Stable
Most abundant stable isotope
|
| Sulfur-33 | ³³S | 16 | 17 | 32.97146 | 0.75% |
Stable
Stable; NMR-active (I=3/2)
|
| Sulfur-34 | ³⁴S | 16 | 18 | 33.96787 | 4.25% |
Stable
Stable; used in isotope ratio mass spec
|
| Sulfur-35 | ³⁵S | 16 | 19 | 34.96903 | Radioactive |
Unstable
β⁻ decay, t½ = 87.37 days; biochemical tracer
|
| Sulfur-36 | ³⁶S | 16 | 20 | 35.96708 | 0.01% |
Stable
Stable; rarest natural sulfur isotope
|
Sulfur-35 (³⁵S) is widely used in molecular biology for radiolabeling amino acids (methionine and cysteine) in protein synthesis studies, and for labeling thiol-containing compounds. Its soft beta emission (Emax = 167 keV) makes it safer to handle than ³²P.
Chemical Properties
Atomic Properties
Sulfur Allotropes
Stable at room temperature. Bright yellow, brittle crystals. The standard form of elemental sulfur. Transitions to monoclinic at 96 °C.
Stable between 96 °C and 119 °C. Pale yellow needle-like crystals. Slowly converts to rhombic sulfur below 96 °C on cooling.
Formed by pouring molten sulfur into cold water. Elastic, rubbery, dark brown. Converts back to crystalline rhombic sulfur over hours to days.
Fine powder produced by condensing sulfur vapor. Used in agriculture as a fungicide and acaricide, and in medicine (topical sulfur preparations).
Key Facts About Sulfur
Sulfuric Acid — World's Top Chemical
Sulfuric acid (H₂SO₄) is the highest-volume industrial chemical produced globally, exceeding 200 million tonnes per year. It is manufactured via the Contact Process (S → SO₂ → SO₃ → H₂SO₄). Key uses include fertilizer production, petroleum refining, battery electrolyte, metal processing, and dye synthesis.
Rubber Vulcanization
In 1839 Charles Goodyear discovered that heating natural rubber with sulfur creates cross-links (polysulfide bridges) between polymer chains, drastically improving elasticity, strength, and heat resistance. This process — vulcanization — enabled modern tires, hoses, gaskets, and countless rubber products used daily.
Essential for Amino Acids
Two of the 20 standard amino acids contain sulfur: methionine (–SCH₃) and cysteine (–SH). Cysteine residues form disulfide bridges (–S–S–) that stabilize protein tertiary and quaternary structures — critical for enzymes, antibodies, and structural proteins like keratin in hair and nails.
Known Since Antiquity
Sulfur (brimstone) is one of the earliest known chemical elements, referenced in ancient texts including the Bible and Homer's Iliad. The Romans used burning sulfur as a fumigant and bleaching agent. Antoine Lavoisier confirmed in 1777 that sulfur is a chemical element, not a compound.
Fossil Fuel Sulfur & Acid Rain
Sulfur impurities in coal and petroleum produce SO₂ when burned, which reacts with atmospheric water to form sulfurous and sulfuric acid — the primary cause of acid rain. Modern refineries desulfurize fuels (hydrodesulfurization), and the recovered elemental sulfur is itself a major industrial feedstock.
Agricultural Fungicide
Elemental sulfur (flowers of sulfur) is one of the oldest and most effective fungicides and acaricides, approved for use in organic farming. It controls powdery mildew, black spot, rust, and spider mites on crops and ornamentals. It works by disrupting cellular respiration in fungal cells.
Summary
Complete reference for Sulfur (S, element 16): atomic data, electron configuration with interactive orbital diagram, isotopes, physical constants with temperature toggle, and key industrial uses.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and the interactive shell diagram.
- Toggle the temperature unit (°C / °F / K) on the physical properties card to convert melting and boiling points.
- Review the isotopes table for the four stable sulfur isotopes and key radioactive tracers.
- Consult the chemical properties panel for electronegativity, ionization energies, and oxidation states.
- Explore the key facts section for industrial applications and historical context.
Use cases
- Look up sulfur constants for chemistry homework or exams.
- Verify atomic data when writing lab reports or research papers.
- Reference isotope data for S-35 radiotracer experiments in biochemistry.
- Check physical properties of sulfur allotropes for safety data sheets.
- Teach or learn sulfur chemistry and its role in industrial processes.
- Confirm electron configuration before writing Lewis structure or VSEPR diagrams.
- Quick-reference oxidation states for inorganic or analytical chemistry work.
- Review electronegativity and ionization energy for spectroscopy applications.