CHEBI:18276 - dihydrogen

Main ChEBI Ontology Automatic Xrefs Reactions Pathways Models
ChEBI Name dihydrogen
ChEBI ID CHEBI:18276
Definition An elemental molecule consisting of two hydrogens joined by a single bond.
Stars This entity has been manually annotated by the ChEBI Team.
Secondary ChEBI IDs CHEBI:5785, CHEBI:13350, CHEBI:25363
Supplier Information ChemicalBook:CB4217972, ChemicalBook:CB7686195
Download Molfile XML SDF
Wikipedia License
Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, hydrogen gas, molecular hydrogen, or simply hydrogen. It is colorless, odorless, non-toxic, and highly combustible. Constituting about 75% of all normal matter, hydrogen is the most abundant chemical element in the universe. Stars, including the Sun, mainly consist of hydrogen in a plasma state, while on Earth, hydrogen is found in water, organic compounds, as dihydrogen, and in other molecular forms. The most common isotope of hydrogen (protium, 1H) consists of one proton, one electron, and no neutrons. In the early universe, the formation of hydrogen's protons occurred in the first second after the Big Bang; neutral hydrogen atoms only formed about 370,000 years later during the recombination epoch as the universe expanded and plasma had cooled enough for electrons to remain bound to protons. Hydrogen gas was first produced artificially in the early 16th century by the reaction of acids with metals. Henry Cavendish, in 1766–81, identified hydrogen gas as a distinct substance and discovered its property of producing water when burned; hence its name means "water-former" in Greek. Understanding the colors of light absorbed and emitted by hydrogen was a crucial part of developing quantum mechanics. Hydrogen, typically nonmetallic except under extreme pressure, readily forms covalent bonds with most nonmetals, contributing to the formation of compounds like water and various organic substances. Its role is crucial in acid-base reactions, which mainly involve proton exchange among soluble molecules. In ionic compounds, hydrogen can take the form of either a negatively charged anion, where it is known as hydride, or as a positively charged cation, H+, called a proton. Although tightly bonded to water molecules, protons strongly affect the behavior of aqueous solutions, as reflected in the importance of pH. Hydride on the other hand, is rarely observed because it tends to deprotonate solvents, yielding H2. Industrial hydrogen production occurs through steam reforming of natural gas. The more familiar electrolysis of water is uncommon because it is energy-intensive, i.e. expensive. Its main industrial uses include fossil fuel processing, such as hydrocracking and hydrodesulfurization. Ammonia production also is a major consumer of hydrogen. Fuel cells for electricity generation from hydrogen is rapidly emerging.
Read full article at Wikipedia
Formula H2
Net Charge 0
Average Mass 2.01588
Monoisotopic Mass 2.01565
InChI InChI=1S/H2/h1H
InChIKey UFHFLCQGNIYNRP-UHFFFAOYSA-N
SMILES [H][H]
Metabolite of Species Details
Homo sapiens (NCBI:txid9606) See: DOI
Roles Classification
Chemical Role(s): antioxidant
A substance that opposes oxidation or inhibits reactions brought about by dioxygen or peroxides.
electron donor
A molecular entity that can transfer an electron to another molecular entity.
Biological Role(s): human metabolite
Any mammalian metabolite produced during a metabolic reaction in humans (Homo sapiens).
food packaging gas
A food additive that is a (generally inert) gas which is used to envelop foodstuffs during packing and so protect them from unwanted chemical reactions such as food spoilage or oxidation during subsequent transport and storage. The term includes propellant gases, used to expel foods from a container.
Application(s): fuel
An energy-rich substance that can be transformed with release of usable energy.
food packaging gas
A food additive that is a (generally inert) gas which is used to envelop foodstuffs during packing and so protect them from unwanted chemical reactions such as food spoilage or oxidation during subsequent transport and storage. The term includes propellant gases, used to expel foods from a container.
View more via ChEBI Ontology
ChEBI Ontology
Outgoing dihydrogen (CHEBI:18276) has role antioxidant (CHEBI:22586)
dihydrogen (CHEBI:18276) has role electron donor (CHEBI:15022)
dihydrogen (CHEBI:18276) has role food packaging gas (CHEBI:77974)
dihydrogen (CHEBI:18276) has role fuel (CHEBI:33292)
dihydrogen (CHEBI:18276) has role human metabolite (CHEBI:77746)
dihydrogen (CHEBI:18276) is a elemental hydrogen (CHEBI:33260)
dihydrogen (CHEBI:18276) is a elemental molecule (CHEBI:25362)
dihydrogen (CHEBI:18276) is a gas molecular entity (CHEBI:138675)
Incoming dideuterium (CHEBI:29294) is a dihydrogen (CHEBI:18276)
diprotium (CHEBI:29299) is a dihydrogen (CHEBI:18276)
ditritium (CHEBI:29298) is a dihydrogen (CHEBI:18276)
H group (CHEBI:64428) is substituent group from dihydrogen (CHEBI:18276)
IUPAC Name
dihydrogen
Synonyms Sources
dihydrogen ChEBI
E 949 ChEBI
E-949 ChEBI
E949 ChEBI
H2 KEGG COMPOUND
H2 IUPAC
H2 UniProt
Hydrogen KEGG COMPOUND
molecular hydrogen ChEBI
Manual Xrefs Databases
748 MolBase
C00282 KEGG COMPOUND
HMDB0001362 HMDB
Hydrogen Wikipedia
HYDROGEN-MOLECULE MetaCyc
View more database links
Registry Numbers Types Sources
1333-74-0 CAS Registry Number KEGG COMPOUND
1333-74-0 CAS Registry Number ChemIDplus
1333-74-0 CAS Registry Number NIST Chemistry WebBook
3 Gmelin Registry Number Gmelin
3587189 Reaxys Registry Number Reaxys
Citations Types Sources
15303745 PubMed citation Europe PMC
16517646 PubMed citation Europe PMC
18706888 PubMed citation Europe PMC
19905000 PubMed citation Europe PMC
19908827 PubMed citation Europe PMC
20568549 PubMed citation Europe PMC
24171421 PubMed citation Europe PMC
Last Modified
13 October 2017