Sulfur

Sulfur (S) is a reactive nonmetal with atomic number 16 and an atomic mass of 32.06. Its electron configuration is [Ne] 3s2 3p4, which gives it 6 valence electrons.

Sulfur key data

Symbol	S
Atomic number	16
Atomic mass (standard atomic weight)	32.06
Molar mass	32.06 g/mol
Protons	16
Neutrons (most abundant isotope, sulfur-32)	16
Electrons (neutral atom)	16
Valence electrons	6
Category	Reactive nonmetal
Period	3
Group	16
Block	p-block
Noble gas notation	[Ne] 3s2 3p4
Full electron configuration	1s2 2s2 2p6 3s2 3p4
Electrons per shell	2, 8, 6

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

Measured properties of sulfur

From PubChem, the US National Institutes of Health. Public domain.

Melting point	388.36 K (115.21 °C), 82nd of 103 by melting point
Boiling point	717.75 K (444.6 °C), 78th of 93 by boiling point
Density	2.067 g/cm³, 76th of 96 by density
State at room temperature	Solid
Electronegativity	2.58 (Pauling), 9th of 95 by electronegativity
Van der Waals radius	180 pm, joint 81st of 99 by atomic radius
First ionisation energy	10.36 eV (999.6 kJ/mol), 17th of 102 by first ionisation energy
Electron affinity	2.077 eV (200.4 kJ/mol), 8th of 57 by electron affinity
Common oxidation states	+6, +4, −2
Discovered	Ancient

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Sulfur electron configuration

The full electron configuration of sulfur is 1s2 2s2 2p6 3s2 3p4. With the noble-gas core collapsed it is [Ne] 3s2 3p4, and the outermost subshell is 3p4.

Bohr model of sulfur (S): a nucleus and three shells holding 2, 8 and 6 electrons from the inside out. — Bohr model of sulfur (S). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Orbital box diagram of sulfur (S), 1s2 2s2 2p6 3s2 3p4: one box per orbital, filled by Hund’s rule, showing two unpaired electrons, in 3p. — Orbital diagram of sulfur (S). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one sulfur atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

one atom = 32.06 / (6.02214076 × 10²³)
= 5.3237 × 10⁻²³ g

Atoms in one gram

atoms per gram = 6.02214076 × 10²³ / 32.06
= 1.8784 × 10²² atoms

Sulfur on the periodic table

Sulfur is in period 3, group 16, in the p-block.

The other elements of group 16 are oxygen, selenium, tellurium, polonium and livermorium.