Oxygen
Definition and meaning of Oxygen in chemistry.
Oxygen is a chemical element with the symbol O and atomic number 8. It is a highly reactive nonmetal and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, constituting roughly 46% of the planet's crust by mass.
In more detail
At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This diatomic gas constitutes about 20.9% of the Earth's atmosphere. Oxygen is continuously replenished in the Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. In biological systems, it plays a vital role in cellular respiration, where it acts as the terminal electron acceptor in the electron transport chain to generate ATP. Industrially, oxygen is produced by the fractional distillation of liquefied air or by using zeolites with pressure-swing adsorption to concentrate oxygen from air. It is primarily used in steel production, welding, and medical applications.
Key facts
| Field | General Chemistry |
|---|---|
| Formula | O2 |
| Molar mass | 31.999 g/mol |
| State at STP | Gas |
| Boiling point | -183.0 °C |
During combustion, oxygen reacts rapidly with a fuel source, such as methane in natural gas, to release heat, water, and carbon dioxide.
Frequently asked questions
Why is oxygen necessary for human survival?
Oxygen is required for cellular respiration, a metabolic process that extracts energy from nutrients and produces ATP, which powers cellular functions.
Is oxygen flammable?
Oxygen itself is not flammable, but it is an oxidizer that vigorously supports and accelerates the combustion of other materials.