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Chemical substance record

Dioxygen

7782-44-7O231.998 g/mol
ElementChEBI source record

Dioxygen is indexed in ChEBI under CHEBI:15379, with the reported formula O2. Use the source record and structural identifiers below to confirm the material you need. — ChEBI

Safety references

Safety documents & references

1 indexed references
JP · NITE

Government GHS classification

21C0005 · FY2009

View classification

Find a product-specific SDS

Safety guides and government classification records are not a manufacturer’s SDS. Match supplier, product number, concentration, physical form, region and revision before using a document.

Identity & molecular properties

Source-linked values
CAS number7782-44-7ChEBI ↗
Molecular formulaO2ChEBI ↗
Molar mass31.998 g/molChEBI ↗
Monoisotopic mass31.98983 DaChEBI ↗
Formal charge0ChEBI ↗
ChEBI identifierCHEBI:15379ChEBI ↗

Cross-source molecular data

PubChem
Molar mass31.999 g/molPubChem ↗
Exact mass31.989829239 DaPubChem ↗

PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.

Names & structural identifiers

Copy any identifier
dioxygen
dioxygen
MYMOFIZGZYHOMD-UHFFFAOYSA-N
O=O
InChI=1S/O2/c1-2

Classification & relationships

ChEBI ontology

Roles recorded in ChEBI

micronutrientnutrientreagentanti-inflammatory drugoxidising agentSaccharomyces cerevisiae metabolitehuman metabolitefood packaging gas

Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.

Safety classification · Japan

NITE / Japanese government
Japan · FY2009 source classification
Oxygen · 21C0005
EndpointReported classification
Specific target organ toxicity - Single exposureCategory 3 (Respiratory tract irritation)

Selected source-reported endpoints. Other endpoints, rationales and conditions remain in the original classification. Missing or unlisted information does not mean non-hazardous. This is not a global classification or transport decision.

Read the original NITE classification

Mass ↔ amount of substance

Calculated from sourced mass
Equivalent amount
0.031252 mol

Uses 31.998 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.

Elemental composition

Theoretical mass fractions
O
Oxygen · 2 atoms
100.00%

Calculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.

Research & patent references

Selected source associations
Oxygen: the air-borne nutrient that both sustains and threatens life. ↗Nutrition (Burbank, Los Angeles County, Calif.) · 2000 Jul-Aug · PMID 10906528
Oxygen-dependent differentiation of human keratinocytes. ↗The Journal of investigative dermatology · 2007 Feb · PMID 16977326

Sources & record history

Checked 27 Sep 2026
EMBL-EBI ChEBI · CHEBI:15379

Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0

NCBI PubChem · CID 977 · retrieved 2026-09-27

PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.