O₂
What we inhale
O₂ is the chemical formula for molecular oxygen—two oxygen atoms bonded together.
This is the form of oxygen we breathe, making up about 21% of Earth's atmosphere.
The subscript 2 distinguishes it from O (a single oxygen atom) and O₃ (ozone).
In medical contexts, O₂ often refers to supplemental oxygen: The patient is on O₂.
Having two atoms
- oxidizerElectron-accepting reactant
- combustionExothermic reaction with oxygen
- reactiveTending to respond
- covalent bondShared-electron atomic link
paramagnetic · ozone · redox · electron · valence · atmosphere · photosynthesis · electrolysis
Pulmonary gas exchange
- inhalationTaking breath in
- aerobicRequiring free oxygen
- cellular respirationCell-level fuel burning
- mitochondriaCell's energy-producing organelles
ATP · metabolism · hemoglobin · blood · lungs · alveoli · gas exchange · hypoxia
Heat-fusing metal pieces
- steelmakingIndustrial alloy production
- cutting torchFlame tool that severs metal
- blast furnaceOre-to-metal converter
- smeltingExtracting metal from ore
combustion · rocket propellant · cryogenic · LOX · pressure vessel · cylinder · water treatment · aquaculture
Nostril oxygen delivery device
- ventilatorMechanical breathing apparatus
- hyperbaricAbove atmospheric pressure
- COPDChronic obstructive pulmonary disease
- concentratorDevice that intensifies beams
nebulizer · resuscitation · ICU · anesthesia · blood gas · intubation · respiratory distress · flow rate
England's capital city
- concert venuePlace for live performances
- telecommunicationsRemote signal transmission technology
- mobile networkWireless telecommunications infrastructure
- UKBritish sovereign state
sponsorship · dome · Greenwich · entertainment · stadium · British · carrier · wireless
diatomic
Having two atoms
- oxidizerElectron-accepting reactant
- combustionExothermic reaction with oxygen
- reactiveTending to respond
covalent bond · paramagnetic · ozone · redox · electron · valence · atmosphere · photosynthesis · electrolysis · double bond
breathing
Pulmonary gas exchange
- inhalationTaking breath in
- aerobicRequiring free oxygen
- cellular respirationCell-level fuel burning
mitochondria · ATP · metabolism · hemoglobin · blood · lungs · alveoli · gas exchange · hypoxia · saturation
welding
Heat-fusing metal pieces
- steelmakingIndustrial alloy production
- cutting torchFlame tool that severs metal
- blast furnaceOre-to-metal converter
smelting · combustion · rocket propellant · cryogenic · LOX · pressure vessel · cylinder · water treatment · aquaculture · aerospace
nasal cannula
Nostril oxygen delivery device
- ventilatorMechanical breathing apparatus
- hyperbaricAbove atmospheric pressure
- COPDChronic obstructive pulmonary disease
concentrator · nebulizer · resuscitation · ICU · anesthesia · blood gas · intubation · respiratory distress · flow rate
London
England's capital city
- concert venuePlace for live performances
- telecommunicationsRemote signal transmission technology
- mobile networkWireless telecommunications infrastructure
UK · sponsorship · dome · Greenwich · entertainment · stadium · British · carrier · wireless
Respiration byproduct, photosynthesis fuel
carbon monoxide · CO · asphyxiant · hydrogen cyanide · toxic gas
O₂nitrogen
Element seven, colorless gas
inert gas · noble gases · reducing agent · ozone · argon
oxygen, oxygenate, oxygenation, oxygenated, deoxygenate, deoxygenated, deoxygenation, oxide, oxidize