About

Oxygen is a highly reactive nonmetal essential for aerobic respiration in most terrestrial life and for combustion. It is the third most abundant element in the universe by mass and the most abundant by mass in the Earth's crust, mainly found in oxides and silicates. Its allotrope, ozone (O₃), forms a crucial layer in the stratosphere that protects Earth from ultraviolet radiation.

Atomic Properties

Atomic Number8

Atomic Weight15.999 u

Neutrons (common)8

Electron Configuration[He] 2s² 2p⁴

Full Configuration1s² 2s² 2p⁴

Electrons per Shell2, 6

Electronegativity3.44

Electron Affinity141 kJ/mol

Oxidation States+2, +1, 0, -1, -2

Covalent Radius64 pm

Van der Waals Radius152 pm

Ionic Radius140 pm

Periodic Table Position

Group16

Period2

BlockP

Chemical SeriesOther nonmetals

Physical Properties

State at STPgas

AppearanceColorless gas

Crystal Structuremonoclinic

Magnetic Orderingparamagnetic

Speed of Sound316 m/s

Thermal Properties

Melting Point54.36 K

Boiling Point90.188 K

Triple Point54.36 K

Thermal Conductivity0.027 W/(m·K)

Specific Heat0.918 J/(g·K)

Molar Heat29.378 J/(mol·K)

Heat of Fusion0.444 kJ/mol

Heat of Vaporization6.82 kJ/mol

Abundance

In Earth's Crust461,000 ppm

In Ocean857,000 ppm

In Solar System8,260 ppm

In Human Body614,300 ppm

In Universe10,000 ppm

Discovery

Discovered byCarl Wilhelm Scheele & Joseph Priestley

Discovery Year1,774

Occurrenceprimordial

CAS Number7782-44-7

Electron Configuration

Energy

↿⇂

↿

Isotopes of Oxygen

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
¹⁵O	15.003065	—	122.266 s	Positron Emission
¹⁶O	15.994914	99.757%	Stable	Stable
¹⁷O	16.999131	0.038%	Stable	Stable
¹⁸O	17.999160	0.205%	Stable	Stable

Interactive Visualization

Explore the 3D Bohr model of Oxygen in our interactive viewer.

View 3D Model of Oxygen