O
Oxygen is the third most abundant element in the universe and essential for respiration in most life forms.
Physical Properties
| Atomic Mass | 15.999 u |
| Density | 0.001429 g/cm³ |
| Melting Point | 54.36 K |
| Boiling Point | 90.2 K |
| Appearance | Colorless gas, pale blue liquid |
| State at Room Temp | Gas |
Chemical Properties
| Electronegativity | 3.44 (Pauling) |
| 1st Ionization Energy | 1313.9 kJ/mol |
| Electron Affinity | 140.98 kJ/mol |
| Oxidation States | -2, -1, +1, +2 |
Atomic Properties
| Electron Configuration | [He] 2s2 2p4 |
| Atomic Radius | 48.0 pm |
| Covalent Radius | 66.0 pm |
| Van der Waals Radius | 152.0 pm |
Discovery
| Discovered By | Carl Wilhelm Scheele |
| Discovery Year | 1771 |
| Location | Uppsala, Sweden |
| Named After | Greek 'oxy genes' meaning acid-forming |
About Oxygen
Oxygen is a highly reactive nonmetal and the most abundant element in Earth's crust. It readily forms oxides with most elements. Oxygen is essential for cellular respiration and combustion. The ozone layer protects life on Earth from ultraviolet radiation.
Uses & Applications
Steelmaking, medical breathing gas, welding and cutting, water treatment, rocket propellant, and chemical manufacturing.
Fun Fact
Oxygen is paramagnetic -- liquid oxygen is pale blue and can be suspended between the poles of a strong magnet.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 16 | 0.99757% | - | Yes |
| 17 | 0.00038% | - | Yes |
| 18 | 0.00205% | - | Yes |
Electron Configuration
[He] 2s2 2p4