{"slug":"diatomic-and-monatomic-elements","title":"List of diatomic molecules and monatomic elements","shortTitle":"Diatomic and monatomic elements","description":"A curated reference list of common elemental diatomic molecules and monatomic noble gases with formulas, categories, and source identifiers.","seoTitle":"List of diatomic molecules and monatomic elements","seoDescription":"Browse a curated list of diatomic molecules and monatomic elements with formulas, PubChem identifiers, source notes, and downloadable CSV/JSON data.","keywords":["list of diatomic molecule","list of diatomic molecules","list of monatomic and diatomic elements","diatomic elements list","monatomic elements list"],"aliases":["list-of-diatomic-molecule","list-of-diatomic-molecules","list-of-monatomic-and-diatomic-elements"],"updatedAt":"2026-05-02","audience":"Chemistry students, instructors, and researchers who need a small, source-backed elemental molecule reference.","methodology":"The starter list separates stable elemental diatomic molecules from monatomic noble gases. PubChem supplies compound identifiers where available, while NIST is cited for reference data on selected diatomic species.","expansionPlan":"The expanded dataset should add radicals, ions, isotopologues, and transient diatomic species as separate filtered views so the basic educational list remains readable.","sources":[{"name":"PubChem","url":"https://pubchem.ncbi.nlm.nih.gov/","role":"Canonical compound identifiers, names, formulas, structures, SMILES, and downloadable compound records.","licenseNote":"NCBI places no restrictions on PubChem data, though original submitters may retain rights in submitted records."},{"name":"NIST Chemistry WebBook","url":"https://webbook.nist.gov/chemistry/","role":"Reference physical chemistry data and diatomic constants for selected species.","licenseNote":"NIST SRD 69 should be cited and linked rather than mirrored wholesale."},{"name":"OpenStax Chemistry","url":"https://openstax.org/details/books/chemistry-2e","role":"Chemistry definitions used for educational polarity, bonding, organic chemistry, and molecule-class explanations."}],"columns":[{"key":"name","label":"Name"},{"key":"formula","label":"Formula"},{"key":"molecularWeight","label":"MW (g/mol)"},{"key":"classification","label":"Classification"},{"key":"category","label":"Basis"},{"key":"smiles","label":"SMILES"},{"key":"pubchemCid","label":"PubChem CID"},{"key":"sourceIds","label":"Source IDs"},{"key":"notes","label":"Notes"}],"rows":[{"id":"hydrogen","name":"Hydrogen","formula":"H2","classification":"Diatomic molecule","category":"Elemental diatomic gas","smiles":"[H][H]","pubchemCid":"783","sourceIds":["PubChem CID 783","NIST diatomic constants"],"notes":"One of the seven commonly taught elemental diatomic molecules.","molecularWeight":2.02},{"id":"nitrogen","name":"Nitrogen","formula":"N2","classification":"Diatomic molecule","category":"Elemental diatomic gas","smiles":"N#N","pubchemCid":"947","sourceIds":["PubChem CID 947","NIST diatomic constants"],"notes":"Major component of Earth atmosphere.","molecularWeight":28.01},{"id":"oxygen","name":"Oxygen","formula":"O2","classification":"Diatomic molecule","category":"Elemental diatomic gas","smiles":"O=O","pubchemCid":"977","sourceIds":["PubChem CID 977","NIST diatomic constants"],"notes":"Paramagnetic elemental oxygen molecule.","molecularWeight":32},{"id":"fluorine","name":"Fluorine","formula":"F2","classification":"Diatomic molecule","category":"Halogen diatomic molecule","smiles":"FF","pubchemCid":"24524","sourceIds":["PubChem CID 24524"],"molecularWeight":38},{"id":"chlorine","name":"Chlorine","formula":"Cl2","classification":"Diatomic molecule","category":"Halogen diatomic molecule","smiles":"ClCl","pubchemCid":"24526","sourceIds":["PubChem CID 24526"],"molecularWeight":70.9},{"id":"bromine","name":"Bromine","formula":"Br2","classification":"Diatomic molecule","category":"Halogen diatomic molecule","smiles":"BrBr","pubchemCid":"24408","sourceIds":["PubChem CID 24408"],"molecularWeight":159.81},{"id":"iodine","name":"Iodine","formula":"I2","classification":"Diatomic molecule","category":"Halogen diatomic molecule","smiles":"II","pubchemCid":"807","sourceIds":["PubChem CID 807"],"molecularWeight":253.8},{"id":"helium","name":"Helium","formula":"He","classification":"Monatomic element","category":"Noble gas","smiles":"[He]","pubchemCid":"23987","sourceIds":["PubChem CID 23987"],"molecularWeight":4},{"id":"neon","name":"Neon","formula":"Ne","classification":"Monatomic element","category":"Noble gas","smiles":"[Ne]","pubchemCid":"23935","sourceIds":["PubChem CID 23935"],"molecularWeight":20.18},{"id":"argon","name":"Argon","formula":"Ar","classification":"Monatomic element","category":"Noble gas","smiles":"[Ar]","pubchemCid":"23968","sourceIds":["PubChem CID 23968"],"molecularWeight":39.95},{"id":"krypton","name":"Krypton","formula":"Kr","classification":"Monatomic element","category":"Noble gas","smiles":"[Kr]","pubchemCid":"5416","sourceIds":["PubChem CID 5416"],"molecularWeight":83.8},{"id":"xenon","name":"Xenon","formula":"Xe","classification":"Monatomic element","category":"Noble gas","smiles":"[Xe]","pubchemCid":"23991","sourceIds":["PubChem CID 23991"],"molecularWeight":131.29},{"id":"radon","name":"Radon","formula":"Rn","classification":"Monatomic element","category":"Noble gas","smiles":"[Rn]","pubchemCid":"24857","sourceIds":["PubChem CID 24857"],"molecularWeight":222},{"id":"carbon-monoxide","name":"Carbon Monoxide","formula":"CO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[C-]#[O+]","pubchemCid":"281","sourceIds":["PubChem CID 281"],"molecularWeight":28.01},{"id":"nitric-oxide","name":"Nitric Oxide","formula":"NO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[N]=O","pubchemCid":"145068","sourceIds":["PubChem CID 145068"],"molecularWeight":30.01},{"id":"hydrogen-chloride","name":"Hydrogen Chloride","formula":"ClH","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"Cl","pubchemCid":"313","sourceIds":["PubChem CID 313"],"molecularWeight":36.46},{"id":"hydrogen-fluoride","name":"Hydrogen Fluoride","formula":"FH","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"F","pubchemCid":"14917","sourceIds":["PubChem CID 14917"],"molecularWeight":20.01},{"id":"hydrogen-bromide","name":"Hydrogen Bromide","formula":"BrH","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"Br","pubchemCid":"260","sourceIds":["PubChem CID 260"],"molecularWeight":80.91},{"id":"hydrogen-iodide","name":"Hydrogen Iodide","formula":"HI","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"I","pubchemCid":"24841","sourceIds":["PubChem CID 24841"],"molecularWeight":127.91},{"id":"hydrogen-cyanide","name":"Hydrogen Cyanide","formula":"CHN","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"C#N","pubchemCid":"768","sourceIds":["PubChem CID 768"],"molecularWeight":27.03},{"id":"sodium-chloride","name":"Sodium Chloride","formula":"ClNa","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[Na+].[Cl-]","pubchemCid":"5234","sourceIds":["PubChem CID 5234"],"molecularWeight":58.44},{"id":"potassium-chloride","name":"Potassium Chloride","formula":"ClK","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[Cl-].[K+]","pubchemCid":"4873","sourceIds":["PubChem CID 4873"],"molecularWeight":74.55},{"id":"lithium-hydride","name":"Lithium Hydride","formula":"HLi","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[H-].[Li+]","pubchemCid":"62714","sourceIds":["PubChem CID 62714"],"molecularWeight":7.95},{"id":"sodium-hydride","name":"Sodium Hydride","formula":"HNa","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[H-].[Na+]","pubchemCid":"24758","sourceIds":["PubChem CID 24758"],"molecularWeight":24},{"id":"potassium-hydride","name":"Potassium Hydride","formula":"HK","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[H-].[K+]","pubchemCid":"82127","sourceIds":["PubChem CID 82127"],"molecularWeight":40.11},{"id":"lithium-fluoride","name":"Lithium Fluoride","formula":"FLi","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[Li+].[F-]","pubchemCid":"224478","sourceIds":["PubChem CID 224478"],"molecularWeight":25.94},{"id":"sodium-fluoride","name":"Sodium Fluoride","formula":"FNa","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[F-].[Na+]","pubchemCid":"5235","sourceIds":["PubChem CID 5235"],"molecularWeight":41.99},{"id":"potassium-fluoride","name":"Potassium Fluoride","formula":"FK","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[F-].[K+]","pubchemCid":"522689","sourceIds":["PubChem CID 522689"],"molecularWeight":58.1},{"id":"lithium-chloride","name":"Lithium Chloride","formula":"ClLi","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[Li+].[Cl-]","pubchemCid":"433294","sourceIds":["PubChem CID 433294"],"molecularWeight":42.39},{"id":"potassium-bromide","name":"Potassium Bromide","formula":"BrK","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[K+].[Br-]","pubchemCid":"253877","sourceIds":["PubChem CID 253877"],"molecularWeight":119},{"id":"sodium-iodide","name":"Sodium Iodide","formula":"INa","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[Na+].[I-]","pubchemCid":"5238","sourceIds":["PubChem CID 5238"],"molecularWeight":149.89},{"id":"silicon-monoxide","name":"Silicon Monoxide","formula":"OSi","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=[Si]","pubchemCid":"66241","sourceIds":["PubChem CID 66241"],"molecularWeight":44.08},{"id":"sulfur-monoxide","name":"Sulfur Monoxide","formula":"OS","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=S","pubchemCid":"114845","sourceIds":["PubChem CID 114845"],"molecularWeight":48.06},{"id":"phosphorus-monoxide","name":"Phosphorus Monoxide","formula":"OP","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=[P]","pubchemCid":"6857426","sourceIds":["PubChem CID 6857426"],"molecularWeight":46.97},{"id":"aluminum-monoxide","name":"Aluminum Monoxide","formula":"AlO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=[Al]","pubchemCid":"142249","sourceIds":["PubChem CID 142249"],"molecularWeight":42.98},{"id":"magnesium-oxide","name":"Magnesium Oxide","formula":"MgO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=[Mg]","pubchemCid":"14792","sourceIds":["PubChem CID 14792"],"molecularWeight":40.3},{"id":"calcium-oxide","name":"Calcium Oxide","formula":"CaO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O=[Ca]","pubchemCid":"14778","sourceIds":["PubChem CID 14778"],"molecularWeight":56.08},{"id":"boron-nitride","name":"Boron Nitride","formula":"BN","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"B#N","pubchemCid":"66227","sourceIds":["PubChem CID 66227"],"molecularWeight":24.82},{"id":"carbon-monosulfide","name":"Carbon Monosulfide","formula":"CS","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[C-]#[S+]","pubchemCid":"108054","sourceIds":["PubChem CID 108054"],"molecularWeight":44.07},{"id":"cyanogen","name":"Cyanogen","formula":"C2N2","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"C(#N)C#N","pubchemCid":"9999","sourceIds":["PubChem CID 9999"],"molecularWeight":52.04},{"id":"dicarbon","name":"Dicarbon","formula":"C2H2","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"C#C","pubchemCid":"6326","sourceIds":["PubChem CID 6326"],"molecularWeight":26.04},{"id":"boron-monoxide","name":"Boron Monoxide","formula":"BO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[B]=O","pubchemCid":"6327189","sourceIds":["PubChem CID 6327189"],"molecularWeight":26.81},{"id":"chlorine-monoxide","name":"Chlorine Monoxide","formula":"Cl2O","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"O(Cl)Cl","pubchemCid":"24646","sourceIds":["PubChem CID 24646"],"molecularWeight":86.9},{"id":"nitrosyl-chloride","name":"Nitrosyl Chloride","formula":"ClNO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"N(=O)Cl","pubchemCid":"17601","sourceIds":["PubChem CID 17601"],"molecularWeight":65.46},{"id":"hydroxyl-radical","name":"Hydroxyl Radical","formula":"HO","category":"Heteronuclear diatomic molecule","classification":"Diatomic molecule","smiles":"[OH]","pubchemCid":"157350","sourceIds":["PubChem CID 157350"],"molecularWeight":17.01}]}