Sulfur Facts

Sulfur is the 16th element of the periodic table. These sulfur facts contain chemical and physical data along with general information and history.

Element cell for Sulfur

Sulfur Periodic Table Cell

Basic Sulfur Facts

Name: Sulfur

Atomic Number: 16

Element Symbol: S

Group: 16

Period: 3

Block: p

Element Family: Nonmetal

Atomic Mass: [32.059; 32.076]
IUPAC guidelines to reflect the physical and chemical history of the magnesium sample. If a single value of the atomic mass is needed, use 32.066.

Electron Configuration: [Ne]3s23p4 (shorthand) or 1s22s22p63s23p(full)

Discovery: Ancient times

People have known about sulfur since ancient times. It is one of the few elements which can be found in native form. Sulfur has been known by many names: sufra (Arabic word for yellow), brimstone, shulbari (Sanskrit for ‘enemy of copper’) and sulfurium (Latin). It was recognized as an element by French chemist Antoine Lavoisier in 1789.

Name Origin: Sulfur was taken from the Latin spelling of sulfurium. The -ium suffix was dropped because sulfur was not a metal.

Spelling: The f in sulfur was formally adopted by the IUPAC in 1990. Sulphur was used by British chemists since the 19th Century. In 1992, the Royal Society formalized the British spelling to sulfur.


Natural sulfur is comprised of four stable isotopes: 32S, 33S, 34S, and 36S. Twenty one radioactive isotopes exist ranging from 26S to 49S.

Sulfur-32 is a stable isotope containing 16 neutrons. 95.02% of natural sulfur is sulfur-32.

Sulfur-33 is a stable isotope containing 17 neutrons. 0.75% of natural sulfur is sulfur-33.

Sulfur-34 is a stable isotope containing 18 neutrons. 4.21% of natural sulfur is sulfur-34.

Sulfur-36 is a stable isotope containing 20 neutrons. 0.02% of natural sulfur is sulfur-36.

Sulfur-35 is a radioactive isotope containing 19 neutrons. Sulfur-35 decays by β- decay into 35Cl with a half-life of 87.51 days. This isotope can be found naturally in trace quantities.

Sulfur Crystals

Small crystals of sulfur. Credit: Ben Mills/Public Domain)

Physical Data

Density:  2.07 g/cm3

Melting Point: 388.36 K ​(115.21 °C, ​239.38 °F)

Boiling Point: 717.8 K ​(444.6 °C, ​832.3 °F)

Critical Point: 1314 K at 20.7 MPa

State at 20ºC: Solid

Heat of Fusion: 1.727 kJ/mol

Heat of Vaporization: 45 kJ/mol

Molar Heat Capacity: 22.75 J/mol·K

Sulfur Atom

Electron shell configuration of a sulfur atom.

Atomic Data

Atomic Radius: 1.80 Å

Covalent Radius: 1.05 Å

Van der Waals Radius:  1.80 Å

Electron Affinity: 200.41 kJ/mol

Electronegativity: 2.58

1st Ionization Energy: 999.589 kJ/mol

2nd Ionization Energy: 2251.763 kJ/mol

3rd Ionization Energy: 3356.72 kJ/mol

4th Ionization Energy: 4556.231 kJ/mol

5th Ionization Energy: 7004.305 kJ/mol

6th Ionization Energy: 8495.824 kJ/mol

7th Ionization Energy: 27107.363 kJ/mol

8th Ionization Energy: 31719.56 kJ/mol

Oxidation States: +6, +4, +2 (common), +5, +3, +1, -1, -2 (uncommon)

Melting and Burning Sulfur

Top: Melting sulfur. Melted liquid sulfur is a blood red color. Bottom: Sulfur burns with a blue flame. Credit: Johannes Hemmerlein/GNU License

Fun Sulfur Facts

  • Sulfur occurs freely in nature as a native element.
  • Sulfur turns red when melting.
  • Sulfur combusts with a blue flame.
  • Sulfur has the greatest number of allotropes of any element. There are 30 known allotropes, but the brittle yellow crystals are the most common.
  • Sulfur is used to vulcanize rubber.
  • Sulfur can be used as an antiseptic and antifungal.
  • Most sulfur is used to manufacture sulfuric acid.
  • Many sulfur compounds are toxic. Hydrogen sulfide deadens your sense of smell and can cause respiratory paralysis and death.
  • Sulfur is mined from salt domes by forcing steam into wells. The steam melts the sulfur and the liquid water and sulfur are pumped out.
  • Another source of sulfur is from its removal as a byproduct of petroleum refining.
  • Sulfur has no smell. The smell generally associated with sulfur is actually from sulfur compounds.

Learn more about elements on the periodic table.

Sulfur Facts
Last modified: May 28th, 2015 by Todd Helmenstine

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