O
15.999Oxygen
Oksijen
Oxygen is a reactive nonmetal gas essential for respiration and combustion. It makes up about 21% of Earth’s atmosphere by volume and is used in steelmaking, medicine, welding, water treatment and chemical production.
8
15.999 g/mol
[He] 2s² 2p⁴
2 | 6
3.44
1.31e-3 g/cm³
-218.8 °C
-182.9 °C
Carl Wilhelm Scheele
Oxygen was discovered independently by Carl Wilhelm Scheele and Joseph Priestley in the 1770s. Antoine Lavoisier later explained its role in combustion and named it oxygen.
Oxygen-16
Natural abundance: About 99.76%. The most abundant stable isotope of oxygen.Oxygen-17
Natural abundance: About 0.04%. Stable isotope used in specialized spectroscopy and isotope studies.Oxygen-18
Natural abundance: About 0.20%. Stable isotope used in isotope tracing, climate studies and enriched water.H₂O
WaterEssential compound for life and a common solvent.CO₂
Carbon DioxideProduct of respiration and combustion; also an important greenhouse gas.H₂O₂
Hydrogen PeroxideOxidizer used in bleaching, disinfection and chemical synthesis.SiO₂
Silicon DioxideMajor component of sand, quartz and glass.- Steelmaking and metal refining
- Medical oxygen and breathing support
- Oxy-acetylene welding and metal cutting
- Production of chemicals such as hydrogen peroxide and nitric acid
- Wastewater and industrial effluent treatment
Oxygen is essential for aerobic respiration in humans and many other organisms. It is also a major component of water, carbohydrates, fats, proteins and many minerals.
- Liquid oxygen is pale blue.
- O₂ is paramagnetic because it has two unpaired electrons in molecular orbitals.
- Oxygen is the most abundant element in Earth’s crust by mass.
- Ozone is a form of oxygen with three oxygen atoms per molecule.
- Stratospheric ozone absorbs much of the Sun’s harmful UV-B radiation.
- Oxygen has atomic number 8 and belongs to group 16.
- Its electron configuration is [He] 2s² 2p⁴.
- Oxygen has six valence electrons and commonly forms O²⁻ in ionic compounds.
- Oxygen usually has oxidation state -2, but it is -1 in peroxides and positive in compounds with fluorine.
What is the atomic number of oxygen?
The atomic number of oxygen is 8.
What is the electron configuration of oxygen?
Oxygen has the electron configuration [He] 2s² 2p⁴.
How much oxygen is in the atmosphere?
Oxygen makes up about 21% of Earth’s atmosphere by volume.
Why is oxygen paramagnetic?
O₂ is paramagnetic because it has two unpaired electrons in molecular orbitals.
What are the allotropes of oxygen?
The main oxygen allotropes are dioxygen (O₂) and ozone (O₃).
What is oxygen used for?
Oxygen is used in steelmaking, medicine, welding and cutting, chemical production, water treatment and respiration support.