Oxygen Element Properties
Complete reference for Oxygen (O, element 8): atomic data, electron configuration with interactive shell diagram, isotopes, physical constants, and a temperature unit toggle.
Oxygen
Nonmetal — Period 2, Group 16
Atomic Identity
Electron Configuration
Two unpaired electrons — triplet ground state (³P₂)
Physical Properties
Isotopes of Oxygen
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Stability |
|---|---|---|---|---|---|---|
| Oxygen-15 | ¹⁵O | 8 | 7 | 15.00307 | Radioactive |
Unstable
β⁺ decay, t½ = 122.24 s |
| Oxygen-16 | ¹⁶O | 8 | 8 | 15.99491 | 99.757% | Stable |
| Oxygen-17 | ¹⁷O | 8 | 9 | 16.99913 | 0.038% | Stable |
| Oxygen-18 | ¹⁸O | 8 | 10 | 17.99916 | 0.205% | Stable |
| Oxygen-19 | ¹⁹O | 8 | 11 | 19.00358 | Radioactive |
Unstable
β⁻ decay, t½ = 26.91 s |
Oxygen-16 (¹⁶O) is a doubly magic nucleus (8 protons and 8 neutrons fill complete nuclear shells), making it exceptionally stable. Oxygen-18 (¹⁸O) is used in paleoclimatology — the ¹⁸O/¹⁶O ratio in ice cores and foraminifera shells reveals past ocean temperatures and ice volumes.
Chemical Properties
Atomic Properties
Key Facts About Oxygen
Atmospheric Abundance
Molecular oxygen (O₂) constitutes approximately 20.95% of Earth's dry atmosphere by volume. Nearly all of this oxygen is of biogenic origin — produced by photosynthesis over approximately 2.4 billion years. The Great Oxidation Event (~2.4 Ga) fundamentally transformed Earth's surface chemistry.
Essential for Aerobic Life
Oxygen serves as the terminal electron acceptor in aerobic cellular respiration. Mitochondria use O₂ to oxidize glucose, producing ATP, CO₂, and water. Approximately 90% of the energy used by aerobic organisms comes from O₂-dependent metabolism. It is also a structural component of water (H₂O), making up nearly 89% of water by mass.
Ozone Layer (O₃)
In the stratosphere (15–35 km altitude), oxygen forms ozone (O₃) that absorbs 97–99% of the Sun's harmful ultraviolet radiation (UV-B and UV-C). Without this shield, most surface life would be destroyed by UV damage to DNA. Chlorofluorocarbons (CFCs) catalytically destroy ozone, leading to the Montreal Protocol (1987).
Steel & Industrial Production
The basic oxygen furnace (BOF) uses pure O₂ blown into molten iron to remove carbon and impurities, producing steel. This process accounts for about 70% of global steel production. LOX (liquid oxygen) is also used in rocket propulsion as a powerful oxidizer paired with liquid hydrogen or RP-1 kerosene in engines like SpaceX's Merlin.
Most Abundant Element in Crust
Oxygen is the most abundant element by mass in Earth's crust (approximately 46%), in the hydrosphere (~89% by mass as water), and in the human body (~65% by mass). As silicates and oxides, oxygen bonds dominate rock-forming minerals — quartz (SiO₂), feldspars, olivine, and carbonates all rely on O²⁻ anions.
Reactive Oxygen Species (ROS)
Partially reduced oxygen species — superoxide (O₂⁻·), hydrogen peroxide (H₂O₂), hydroxyl radical (·OH), and singlet oxygen (¹O₂) — are collectively called reactive oxygen species. ROS play dual roles: at low levels they act as signaling molecules; at high levels they cause oxidative stress, damaging DNA, proteins, and lipids. Antioxidants (vitamins C and E, superoxide dismutase) counter ROS damage.
Summary
Complete reference for Oxygen (O, element 8): atomic data, electron configuration with interactive shell diagram, isotopes, physical constants, and a temperature unit toggle.
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 oxygen-16, oxygen-17, and oxygen-18 data including natural abundance.
- Consult the chemical properties panel for electronegativity, ionization energies, and oxidation states.
- Explore the key facts section for biological roles, industrial applications, and atmospheric significance.
Use cases
- Look up oxygen constants for chemistry homework or exams.
- Verify atomic data when writing lab reports or research papers.
- Reference isotope data for stable isotope labeling or mass spectrometry.
- Check physical properties for engineering applications involving liquid oxygen.
- Teach or learn oxygen chemistry and its essential role in biology and combustion.
- Confirm electron configuration before writing molecular orbital diagrams.
- Quick-reference oxidation states for inorganic or analytical chemistry.
- Review electronegativity and ionization energy for spectroscopy or computational chemistry.