List of molecules in interstellar space
Encyclopedia
This is a list of molecules that have been detected in the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

 and circumstellar envelope
Circumstellar envelope
Circumstellar envelope is the part of the star,having roughly spherical shape and not gravitationally bound to the star core.Usually circumstellar envelopes are formed from the dense stellar wind or presentbefore formation of the star...

s, grouped by the number of component atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s. The chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 is listed for each detected compound, along with any ionized form that has also been observed.

Detection

The molecules listed below were detected by spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

. Their spectral features are generated by transitions of component electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s between different energy levels, or by rotational or vibrational spectra. Detection usually occurs in radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

, microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

, or infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 portions of the spectrum. The first such molecule to be detected in the interstellar medium was the methylidyne
Methylidyne
Methylidyne is a carbyne encountered in organic chemistry. Methylidyne has a linear doublet ground state and is thus paramagnetic. It is stable in the gaseous state. Methylidyne can be considered to be a monoradical; addition reactions are very fast and exothermic. Methylidyne tends to polymerise...

 radical (CH) in 1937.

Interstellar molecules are formed by chemical reactions within very sparse interstellar or circumstellar clouds of dust and gas. Usually this occurs when a molecule becomes ionized, often as the result of an interaction with a cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

. This positively-charged molecule then draws in a nearby reactant by electrostatic attraction of the neutral molecule's electrons. Molecules can also be generated by reactions between neutral atoms and molecules, although this process is generally slower. The dust plays a critical role of shielding the molecules from the ionizing effect of ultraviolet radiation emitted by stars.

A particularly large and rich region for detecting interstellar molecules is Sagittarius B2
Sagittarius B2
Sagittarius B2 is a giant molecular cloud of gas and dust that is located about from the center of the Milky Way. This complex is the largest molecular cloud in the vicinity of the core and one of the largest in the galaxy, spanning a region about across. The total mass of Sgr B2 is about 3...

 (Sgr B2). This giant molecular cloud
Molecular cloud
A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen ....

 lies near the center of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

 galaxy and is a frequent target for new searches. About half of the molecules listed below were first found near Sgr B2, and nearly every other molecule has since been detected in this feature. A rich source of investigation for circumstellar molecules is the relatively nearby star CW Leonis (IRC +10216), where about 50 molecules have been identified.

Molecules

The following tables list molecules that have been detected in the interstellar medium, grouped by the number of component atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s. If there is no entry in the Molecule column, only the ionized form has been detected. For molecules where no designation was given in the scientific literature, that field is left empty. Mass is given in Atomic mass unit
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...

s. The total number of unique species is listed in parentheses in each section header.

Diatomic (32)

Molecule|MassAlCl Aluminium monochloride
Aluminium monochloride
Aluminium monochloride is the metal halide with the formula AlCl. This compound is produced as a step in the Alcan process to smelt aluminium from an aluminium-rich alloy...

62.5
AlF Aluminium monofluoride
Aluminium monofluoride
Aluminium monofluoride is the chemical substance with the formula AlF. This elusive species is formed by the reaction between aluminium trifluoride and metallic aluminium at elevated temperatures but quickly reverts back to the reactants when cooled...

46
AlO Aluminium monoxide 43
C2 Diatomic carbon
Diatomic carbon
Diatomic carbon is a diatomic molecule of carbon , which occurs in electric arcs; in comets, stellar atmospheres and the interstellar medium; and in blue hydrocarbon flames.-Chemistry:...

24
Fluoromethylidynium 31 CF+
CH Methylidyne
Methylidyne
Methylidyne is a carbyne encountered in organic chemistry. Methylidyne has a linear doublet ground state and is thus paramagnetic. It is stable in the gaseous state. Methylidyne can be considered to be a monoradical; addition reactions are very fast and exothermic. Methylidyne tends to polymerise...

 radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...

13 CH+

|-
|align="center"|CN||Cyanogen
Cyanogen
Cyanogen is the chemical compound with the formula 2. It is a colorless, toxic gas with a pungent odor.The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups — analogous to diatomic halogen molecules, such as Cl2, but far less oxidizing...

 radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...


|align="center"|26||align="center"|CN+, CN-
|-
|align="center"|CO||Carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...


|align="center"|28||align="center"|CO+
|-
|align="center"|CP||Carbon monophosphide
|align="center"|43||align="center"|—
|-
|align="center"|CS||Carbon monosulfide
Carbon monosulfide
Carbon monosulfide is a chemical compound with the formula CS. This diatomic molecule is the sulfur analogue of carbon monoxide, and is unstable as a solid or a liquid, but it has been observed as a gas both in the laboratory and in the interstellar medium. The molecule resembles carbon monoxide...


|align="center"|44||align="center"|—
|-
|align="center"|FeO||Iron(II) oxide
Iron(II) oxide
Iron oxide, also known as ferrous oxide, is one of the iron oxides. It is a black-colored powder with the chemical formula . It consists of the chemical element iron in the oxidation state of 2 bonded to oxygen. Its mineral form is known as wüstite. Iron oxide should not be confused with rust,...


|align="center"|82||align="center"|—
|-
|align="center"|H2||Molecular hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...


|align="center"|2||align="center"|—
|-
|align="center"|HCl||Hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...


|align="center"|36.5||align="center"|—
|-
|align="center"|HF||Hydrogen fluoride
Hydrogen fluoride
Hydrogen fluoride is a chemical compound with the formula HF. This colorless gas is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers . HF is widely used in the...


|align="center"|20||align="center"|—
|-
|align="center"|HO||Hydroxyl radical
Hydroxyl radical
The hydroxyl radical, •OH, is the neutral form of the hydroxide ion . Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides or, in...


|align="center"|17||align="center"|OH+
|-
|align="center"|KCl||Potassium chloride
Potassium chloride
The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are...


|align="center"|75.5||align="center"|—
|-
|align="center"|NH||Nitrogen monohydride
|align="center"|15||align="center"|—
|-
|align="center"|N2||Molecular nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...


|align="center"|28||align="center"|—
|-
|align="center"|NO||Nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...


|align="center"|30||align="center"|NO+
|-
|align="center"|NS||Nitrogen sulfide
Mononitrogen monosulfide
Mononitrogen monosulfide is an inorganic compound with the formula SN. It is the sulfur analogue of nitric oxide, NO. It can be produced through electrical discharges in mixtures of nitrogen and sulfur compounds, as well as the reaction of nitrogen with sulfur vapor. The valence electrons of this...


|align="center"|46||align="center"|—
|-
|align="center"|NaCl||Sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...


|align="center"|58.5||align="center"|—
|-
|align="center"|—||Magnesium monohydride cation
|align="center"|25.3||align="center"|MgH+
|-
|align="center"|NaI||Sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....


|align="center"|150||align="center"|—
|-
|align="center"|O2||Molecular oxygen
|align="center"|32||align="center"|—
|-
|align="center"|PN||Phosphorus nitride
|align="center"|45||align="center"|—
|-
|align="center"|PO||Phosphorus monoxide
|align="center"|47||align="center"|—
|-
|align="center"|SH||Sulfur monohydride
|align="center"|33||align="center"|SH+
|-
|align="center"|SO||Sulfur monoxide
Sulfur monoxide
Sulfur monoxide is an inorganic compound with formula . It is only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 . It has been detected in space but is rarely encountered intact otherwise.-Structure and bonding:The SO molecule has a triplet ground state similar...


|align="center"|48||align="center"|SO+
|-
|align="center"|SiC||Carborundum
Silicon carbide
Silicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...


|align="center"|40||align="center"|—
|-
|align="center"|SiN||Silicon mononitride
|align="center"|42||align="center"|—
|-
|align="center"|SiO||Silicon monoxide
Silicon monoxide
Silicon monoxide is the chemical compound with the formula SiO. In the vapour phase it is a diatomic molecule. It has been detected in stellar objects and it has been described as the most common oxide of silicon in the universe....


|align="center"|44||align="center"|—
|-
|align="center"|SiS||Silicon monosulfide
|align="center"|60||align="center"|—
|}

Triatomic (37)

Molecule|MassAlNC Aluminium isocyanide 53
AlOH Aluminium hydroxide
Aluminium hydroxide
Aluminium hydroxide, Al3, ATH, sometimes erroneously called Hydrate of alumina, is found in nature as the mineral gibbsite and its three, much more rare forms, polymorphs: bayerite, doyleite and nordstrandite. Closely related are aluminium oxide hydroxide, AlO, and aluminium oxide, Al2O3,...

44
C3 Tricarbon
Tricarbon
Tricarbon or C3 is a small carbon cluster first spectroscopically observed in the beginning 20th century in the tail of a comet by William Huggins and subsequently identified in stellar atmospheres. Tricarbon can be found in interstellar space and can be produced in the laboratory by a process...

36
C2H Ethynyl radical
Ethynyl radical
The ethynyl radical, with chemical formula C2H, is an abundant interstellar polyatomic molecule that does not occur naturally on Earth. It was first observed by electron spin resonance isolated in a solid argon matrix at liquid helium temperatures in 1963 by Cochran and coworkers at the Johns...

25
C2O Dicarbon monoxide
Dicarbon monoxide
Dicarbon monoxide is an extremely reactive molecule that contains two carbon atoms and one oxygen atom. Dicarbon monoxide, covalently bonded, is a product of the photolysis of carbon suboxide. It is closely related to CO, CO2 and C3O2, and other oxocarbons.It is stable enough to observe reactions...

40
C2S Thioxoethenylidene 56
C2P 55
CO2 Carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

44
FeCN Iron cyanide 82
Protonated molecular hydrogen
Protonated molecular hydrogen
Protonated molecular hydrogen, trihydrogen cation, or H3+, is one of the most abundant ions in the universe. It is stable in the interstellar medium due to the low temperature and low density of interstellar space. The role that H3+ plays in the gas-phase chemistry of the ISM is unparalleled by...

3 H3+
H2C Methylene
Methylene
Methylene is a chemical species in which a carbon atom is bonded to two hydrogen atoms. Three different possibilities present themselves:* the -CH2- substituent group: e.g., dichloromethane ....

14
Chloronium
Halonium ion
A halonium ion in organic chemistry is any onium compound containing a halogen atom carrying a positive charge. This cation has the general structure R-X+-R where X is any halogen and R any organic residue and this structure can be cyclic or an open chain molecular structure...

37.5 H2Cl+
H2O Water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

18 H2O+
H2S Hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

34
HCN Hydrogen cyanide 27
HNC Hydrogen isocyanide
Hydrogen isocyanide
Hydrogen isocyanide is a chemical with the molecular formula HNC. It is a minor tautomer of hydrogen cyanide, HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium.- Nomenclature :...

27
HCO Formyl radical 29 HCO+
HCP Phosphaethyne 44
Thioformyl 45 HCS+
HNC Hydrogen isocyanide
Hydrogen isocyanide
Hydrogen isocyanide is a chemical with the molecular formula HNC. It is a minor tautomer of hydrogen cyanide, HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium.- Nomenclature :...

27
Diazenylium
Diazenylium
N2H+, known as diazenylium, was one of the first ions to be observed in interstellar clouds. Since then, it has been observed for a variety of purposes in several different types of interstellar environments...

29 HN2+
HNO Nitroxyl
Nitroxyl
Nitroxyl is the chemical compound HNO. It is well known in the gas phase . In aqueous solution it acts as an acid with the conjugate base NO−, . NO− is the reduced form of nitric oxide and is isoelectronic with dioxygen...

31
Isoformyl 29 HOC+
KCN Potassium cyanide
Potassium cyanide
Potassium cyanide is an inorganic compound with the formula KCN. This colorless crystalline compound, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewelry for chemical gilding and...

65
MgCN Magnesium cyanide 50
MgNC Magnesium isocyanide 50
NH2 Amino radical 16
29 N2H+
N2O Nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

44
NaCN Sodium cyanide
Sodium cyanide
Sodium cyanide is an inorganic compound with the formula NaCN. This highly toxic colorless salt is used mainly in gold mining but has other niche applications...

49
NaOH Sodium hydroxide 40
OCS Carbonyl sulfide
Carbonyl sulfide
Carbonyl sulfide is the chemical compound with the formula OCS. Commonly written as COS, it is a colourless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom...

60
O3 Ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

48
SO2 Sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

64
c-SiC2 c-Silicon dicarbide name="aass226" /> 52
SiCN Silicon carbonitride 54
SiNC Silicon naphthalocyanine 54


Four atoms (22)

Molecule|MassCH3 Methyl 15
l-C3H Propynylidyne
Propynylidyne
Propynylidyne is a chemical compound that has been identified in interstellar space.- Simulated spectrum :A rotational spectrum of the 2Π electronic ground state of l-C3H can be made using the PGopher software and molecular constants extracted from the literature...

37
c-C3H Cyclopropynylidyne 37
C3N Cyanoethynyl 50 C3N
C3O Tricarbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 monoxide
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

52
C3S Tricarbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...

68
Hydronium
Hydronium
In chemistry, a hydronium ion is the cation , a type of oxonium ion produced by protonation of water. This cation is often used to represent the nature of the proton in aqueous solution, where the proton is highly solvated...

19 H3O+
C2H2 Acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...

26
H2CN Methylene
Methylene
Methylene is a chemical species in which a carbon atom is bonded to two hydrogen atoms. Three different possibilities present themselves:* the -CH2- substituent group: e.g., dichloromethane ....

 amidogen
28 H2CN+
H2CO Formaldehyde
Interstellar formaldehyde
Interstellar formaldehyde was first discovered in 1969 by L. Snyder et al.. using the National Radio Astronomy Observatory. Formaldehyde was detected by means of the 111 - 110 ground state rotational transition at 4830 MHz.-Initial discovery:Formaldehyde was first discovered in interstellar...

30
H2CS Thioformaldehyde 46
HCCN 39
Protonated hydrogen cyanide 28 HCNH+
HCNH+
HCNH+, also known as protonated hydrogen cyanide, is a molecular ion of astrophysical interest.- Structure :The ground state structure of HCNH+ is a simple linear molecule...

Protonated carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

45 HOCO+
HCNO Fulminic acid
Fulminic acid
Fulminic acid is a compound with a molecular formula HCNO. This substance was discovered in 1824 by Justus von Liebig. It is an organic acid and an isomer of isocyanic acid, discovered one year later by Friedrich Woehler....

43
HOCN Cyanic acid 43
HOOH Hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

34
HNCO Isocyanic acid
Isocyanic acid
Isocyanic acid is an inorganic compound with the formula HNCO, discovered in 1830 by Liebig and Wöhler. This colourless substance is volatile and poisonous, with a boiling point of 23.5 °C...

43
HNCS Isothiocyanic acid 59
NH3 Ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

17
HSCN Thiocyanic acid
Thiocyanic acid
Thiocyanic acid is a chemical compound with the formula HSCN that exists as a mixture with the isomeric compound isothiocyanic acid . It is the sulfur analog of cyanic acid ....

59
SiC3 Silicon tricarbide  64


Five atoms (16)

Molecule|MassC5 —  60
CH4 Methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

16
c-C3H2 Cyclopropenylidene
Cyclopropenylidene
Cylopropenylidene, or c-C3H2 belongs to a highly reactive class of organic molecules known as carbenes. Due to its reactivity, cyclopropenylidene is only seen terrestrially in the laboratory. However, it is found in significant concentrations in the interstellar medium due to the extreme environment...

38
l-H2C3 Propadienylidene 38
H2CCN Cyanomethyl 40
H2C2O Ketene
Ethenone
Ethenone is the formal name for ketene, an organic compound with formula C2H2O or H2C=C=O. It is the simplest member of the ketene class. It is a tautomer of ethynol.- Properties :...

42
H2CNH Methylenimine 29
Protonated formaldehyde 31 H2COH+
C4H Butadiynyl 49 C4H
HC3N Cyanoacetylene
Cyanoacetylene
Cyanoacetylene is an organic compound with formula or H-C≡C-C≡N. It is the simplest cyanopolyyne. Cyanoacetylene has been detected by spectroscopic methods in interstellar clouds, in the coma of comet Hale–Bopp and in the atmosphere of Saturn's moon Titan....

51
HCC-NC Isocyanoacetylene 51
HCOOH Formic acid
Formic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...

46
NH2CN Cyanamide
Cyanamide
Cyanamide is an organic compound with the formula CN2H2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol deterrent drug in Canada, Europe and Japan. The molecule features a nitrile group attached to an...

42
HC(O)CN Cyanoformaldehyde 55
SiC4 Silicon-carbide cluster 92
SiH4 Silane
Silane
Silane is a toxic, extremely flammable chemical compound with chemical formula SiH4. In 1857, the German chemists and Friedrich Woehler discovered silane among the products formed by the action of hydrochloric acid on aluminum silicide, which they had previously prepared...

32


Six atoms (14)

Molecule|Massc-H2C3O Cyclopropenone 54
C2H4 Ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

28
CH3CN Acetonitrile
Acetonitrile
Acetonitrile is the chemical compound with formula . This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture...

40
CH3NC Methyl isocyanide
Methyl isocyanide
Methyl isocyanide or Isocyanomethane is an organic compound and a member of the isocyanide family. This colorless liquid is structurally similar to the isomeric methyl cyanide , but its reactivity is very different...

40
CH3OH Methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

32
CH3SH Methanethiol
Methanethiol
Methanethiol is a colorless gas with a smell like rotten cabbage. It is a natural substance found in the blood and brain of humans and other animal as well as plant tissues. It is disposed of through animal feces. It occurs naturally in certain foods, such as some nuts and cheese...

48
l-H2C4 Diacetylene
Diacetylene
Diacetylene , with the formula C4H2, is a highly unsaturated hydrocarbon that contains three single bonds and two triple bonds. It is the first in the series of polyynes.-Occurrence:...

50
Protonated cyanoacetylene 52 HC3NH+
HCONH2 Formamide
Formamide
Formamide, also known as methanamide, is an amide derived from formic acid. It is a clear liquid which is miscible with water and has an ammonia-like odor. It is used primarily for manufacturing sulfa drugs and synthesizing vitamins and as a softener for paper and fiber...

44
C5H Pentynylidyne 61
C5N Cyanobutadiynyl 74
HC2CHO Propynal 54
HC4N —  63
CH2CNH Ketenimine
Ketenimine
Ketenimines are a group of organic compounds sharing a common functional group with the general structure R1R2C=C=NR3. A ketenimine is a cumulated alkene and imine and is related to an allene and a ketene.The parent compound is ketenimine or CH2CNH...

40


Seven atoms (8)

Molecule|Massc-C2H4O Ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

44
CH3C2H Methylacetylene
Methylacetylene
Methylacetylene is an alkyne with the chemical formula H3C≡CH. It is a component of MAPP gas along with its isomer 1,2-propadiene , which is commonly used in gas welding...

40
H3CNH2 Methylamine
Methylamine
Methylamine is the organic compound with a formula of CH3NH2. This colourless gas is a derivative of ammonia, but with one H atom replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, THF, and water, or as the anhydrous gas in pressurized...

31
CH2CHCN Acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...

53
H2CHCOH Vinyl alcohol 44
C6H Hexatriynyl 73 C6H
HC4CN Cyanodiacetylene 75
CH3CHO Acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...

44


Eight atoms (9)

Molecule|Mass
H3CC2CN Methylcyanoacetylene 65
H2COHCHO Glycolaldehyde
Glycolaldehyde
Glycolaldehyde is the smallest possible molecule that contains both an aldehyde group and a hydroxyl group. It is the only possible diose, a 2-carbon monosaccharide, although a diose is not strictly a saccharide...

60
HCOOCH3 Methyl formate
Methyl formate
Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of an ester, it is a clear liquid with an ethereal odor, high vapor pressure, and low surface tension.-Production:...

60
CH3COOH Acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

60
H2C6 Hexapentaenylidene 74
CH2CHCHO Propenal
Acrolein
Acrolein is the simplest unsaturated aldehyde. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity...

56
CH2CCHCN Cyanoallene 65
C7H Heptatrienyl radical 85
NH2CH2CN Aminoacetonitrile
Aminoacetonitrile
Aminoacetonitrile is a simple organic compound containing both nitrile and amino groups. It is somewhat similar to the simplest amino acid, glycine...

56

Nine atoms (8)

Molecule|MassCH3C4H Methyldiacetylene 64
CH3OCH3 Dimethyl Ether
Dimethyl ether
Dimethyl ether , also known as methoxymethane, is the organic compound with the formula . The simplest ether, it is a colourless gas that is a useful precursor to other organic compounds and an aerosol propellant. When combusted, DME produces minimal soot and CO, though HC and NOx formation is...

46
CH3CH2CN Propionitrile
Propionitrile
Propanenitrile, Propionitrile or ethyl cyanide, is a nitrile with the molecular formula C2H5CN. It is a clear liquid with an ethereal, sweet odor.-Production:...

55
CH3CONH2 Acetamide
Acetamide
Acetamide is an organic compound with the formula CH3CONH2. It is the simplest amide derived from acetic acid. It finds some use as a plasticizer and as an industrial solvent...

59
CH3CH2OH Ethyl Alcohol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

46
C8H Octatetraynyl 97 C8H
HC7N Cyanohexatriyne or Cyanotriacetylene 99
CH3CHCH2 Propylene (propene)
Propylene
Propene, also known as propylene or methylethylene, is an unsaturated organic compound having the chemical formula C3H6. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons, and it is also second in natural abundance.-Properties:At room temperature and...

42

Ten or more atoms (15)

Atoms|Designation|Ions
10 (CH3)2CO Acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...

58
10 (CH2OH)2 Ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

62
10 CH3CH2CHO Propanal
Propionaldehyde
Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone...

58
10 CH3C5N Methyl-cyano-diacetylene 89
11 HC8CN Cyanotetra-acetylene 123
11 C2H5OCHO Ethyl formate
Ethyl formate
Ethyl formate is an ester formed when ethanol reacts with formic acid . It is also known as ethyl methanoate because formic acid is also known as methanoic acid. Ethyl formate has the characteristic smell of rum and is also partially responsible for the flavor of raspberries.-Exposure:Ethyl...

74
11 CH3C6H Methyltriacetylene 88
11 H3COC2H5 trans-Ethyl methyl ether 60
12 C6H6 Benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

78
12 C3H7CN n-propyl cyanide
Butyronitrile
Butyronitrile or butanenitrile or propyl cyanide, is a nitrile with the formula C3H7CN. This colorless liquid is miscible with most polar organic solvents. It is mainly used as a precursor to the poultry drug amprolium....

69
13 HC10CN Cyanodecapentayne 147
13 HC11N 159
24 C14H10 Anthracene
Anthracene
Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a component of coal-tar. Anthracene is used in the production of the red dye alizarin and other dyes...

178
60 C60 Buckminsterfullerene
Buckminsterfullerene
Buckminsterfullerene is a spherical fullerene molecule with the formula . It was first intentionally prepared in 1985 by Harold Kroto, James Heath, Sean O'Brien, Robert Curl and Richard Smalley at Rice University...

720
70 C70 70-fullerene
Fullerene
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes...

840

Deuterated molecules (10)

These molecules all contain one or more deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...

 atoms, a heavier isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

 of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

.
Atoms|Designation
2 HD Deuterated molecular hydrogen
Hydrogen deuteride
Hydrogen deuteride is a diatomic molecule composed of the two isotopes of hydrogen: the majority isotope 1H protium and 2H deuterium. Its molecular formula is HD.- Availability in nature :...

3 H2D+, HD2+ Trihydrogen cation
3 HDO, D2O Heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

3 DCN Hydrogen cyanide
3 DCO Formyl radical
3 DNC Hydrogen isocyanide
3 N2D+ — 
4 NH2D, NHD2, ND3 Ammonia
4 HDCO, D2CO Formaldehyde
7 CH2DCCH, CH3CCD Methylacetylene

Unconfirmed (8)

Evidence for the existence of the following molecules has been reported in scientific literature, but they have not yet been confirmed.
Atoms|Designation
2 SiH Silylidine
4 PH3 Phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

10 H2NH2CCOOH Glycine
Glycine
Glycine is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.Glycine is a colourless, sweet-tasting crystalline solid...

12 CO(CH2OH)2 1,3-dihydroxypropanone
Dihydroxyacetone
Dihydroxyacetone , or DHA, also known as glycerone, is a simple carbohydrate with formula .DHA is primarily used as an ingredient in sunless tanning products. It is often derived from plant sources such as sugar beets and sugar cane, and by the fermentation of glycerin.-Chemistry:DHA is a...

12 C2H5OCH3 Ethyl methyl ether
18 C10H8+ Naphthalene
Naphthalene
Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...

 cation
24 C24 Graphene
Graphene
Graphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm, who described single-layer...

60 C60+ Buckminsterfullerene
Buckminsterfullerene
Buckminsterfullerene is a spherical fullerene molecule with the formula . It was first intentionally prepared in 1985 by Harold Kroto, James Heath, Sean O'Brien, Robert Curl and Richard Smalley at Rice University...

 cation

See also

  • Astrochemistry
    Astrochemistry
    Astrochemistry is the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium...

  • Chemistry
    Chemistry
    Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

  • Chemical formula
    Chemical formula
    A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

  • Diffuse interstellar band
    Diffuse interstellar band
    Diffuse interstellar bands are absorption features seen in the spectra of astronomical objects in our galaxy. They are caused by the absorption of light by the interstellar medium...

  • Forbidden mechanism
    Forbidden mechanism
    In physics, a forbidden mechanism or forbidden line is a spectral line emitted by atoms undergoing nominally "forbidden" energy transitions not normally allowed by the selection rules of quantum mechanics. In formal physics, this means that the process cannot proceed via the most efficient route...

  • Helium hydride ion
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