A space-filling model of the diatomic molecule dinitrogen, N2
Diatomic molecules (from Greek di- 'two') are molecules composed of only two atoms, of the same or different chemical elements. If a diatomic molecule consists of two atoms of the same element, such as hydrogen (H2) or oxygen (O2), then it is said to be homonuclear. Otherwise, if a diatomic molecule consists of two different atoms, such as carbon monoxide (CO) or nitric oxide (NO), the molecule is said to be heteronuclear. The bond in a homonuclear diatomic molecule is non-polar.
A periodic table showing the elements that exist as homonuclear diatomic molecules under typical laboratory conditions.
The only chemical elements that form stable homonuclear diatomic molecules at standard temperature and pressure (STP) (or at typical laboratory conditions of 1 bar and 25 °C) are the gases hydrogen (H2), nitrogen (N2), oxygen (O2), fluorine (F2), and chlorine (Cl2), and the liquid bromine (Br2).[1]
The noble gases (helium, neon, argon, krypton, xenon, and radon) are also gases at STP, but they are monatomic. The homonuclear diatomic gases and noble gases together are called "elemental gases" or "molecular gases", to distinguish them from other gases that are chemical compounds.[2]
At slightly elevated temperatures, the halogens bromine (Br2) and iodine (I2) also form diatomic gases.[3] All halogens have been observed as diatomic molecules, except for astatine and tennessine, which are uncertain.
Other elements form diatomic molecules when evaporated, but these diatomic species repolymerize when cooled. Heating ("cracking") elemental phosphorus gives diphosphorus (P2). Sulfur vapor is mostly disulfur (S2). Dilithium (Li2) and disodium (Na2)[4] are known in the gas phase. Ditungsten (W2) and dimolybdenum (Mo2) form with sextuple bonds in the gas phase. Dirubidium (Rb2) is diatomic.
^Hammond, C.R. (2012). "Section 4: Properties of the Elements and Inorganic Compounds" (PDF). Handbook of Chemistry and Physics. Archived (PDF) from the original on 11 November 2011.
^Emsley, J. (1989). The Elements. Oxford: Clarendon Press. pp. 22–23. ISBN 9780198555681.
^Whitten, Kenneth W.; Davis, Raymond E.; Peck, M. Larry; Stanley, George G. (2010). Chemistry (9th ed.). Brooks/Cole, Cengage Learning. pp. 337–338. ISBN 9780495391630.
^Lu, Z.W.; Wang, Q.; He, W.M.; Ma, Z.G. (July 1996). "New parametric emissions in diatomic sodium molecules". Applied Physics B. 63 (1): 43–46. Bibcode:1996ApPhB..63...43L. doi:10.1007/BF01112836. S2CID 120378643.
bromine (Br2) and iodine (I2) also form diatomic gases. All halogens have been observed as diatomicmolecules, except for astatine and tennessine, which...
symmetry group of the molecule. Among all the molecular symmetries, diatomicmolecules show some distinct features and they are relatively easier to analyze...
homonuclear molecules are diatomicmolecule, which consist of two atoms, although not all diatomicmolecules are homonuclear. Homonuclear diatomicmolecules include...
carbon vapor is around 28% diatomic, but theoretically this depends on the temperature and pressure. The electrons in diatomic carbon are distributed among...
f = 7 degrees of freedom, the maximum for a diatomicmolecule. At high enough temperatures, all diatomic gases approach this value. Quantum mechanics...
300 to 3000 cm−1 and wavelengths of approximately 30 to 3 µm. For a diatomicmolecule A−B, the vibrational frequency in s−1 is given by ν = 1 2 π k / μ...
208 Å. A useful conversion factor is 1 D = 3.335 64×10−30 C m. For diatomicmolecules there is only one (single or multiple) bond so the bond dipole moment...
paramagnetic diatomic. The bond order of diatomic oxygen is two. MO treatment of dioxygen is different from that of the previous diatomicmolecules because...
formula (•N=O or •NO). Nitric oxide is also a heteronuclear diatomicmolecule, a class of molecules whose study spawned early modern theories of chemical bonding...
second-most common diatomicmolecule in the interstellar medium, after molecular hydrogen. Because of its asymmetry, this polar molecule produces far brighter...
Indonesia, a hotel in Jakarta, Indonesia Hydrogen iodide, in chemistry, a diatomicmolecule Health informatics, a discipline at the intersection of information...
is also known as the von Neumann–Wigner theorem. In the case of a diatomicmolecule (with one parameter, namely the bond length), this means that the...
the molecule from one rotational energy level to the other through gain or loss of a photon. Analysis is simple in the case of diatomicmolecules. Quantum...
spacings, and their size can be understood by comparing the energy of a diatomicmolecule with internuclear spacing ~ 1 Å to the energy of a valence electron...
for the potential energy of a diatomicmolecule. It is a better approximation for the vibrational structure of the molecule than the quantum harmonic oscillator...
bond in elemental nitrogen (N≡N), the second strongest bond in any diatomicmolecule after carbon monoxide (CO), dominates nitrogen chemistry. This causes...
is present in the oxidation state +2. In the vapour phase, it is a diatomicmolecule. It has been detected in stellar objects and has been described as...
chloride, is also commonly given the formula HCl. Hydrogen chloride is a diatomicmolecule, consisting of a hydrogen atom H and a chlorine atom Cl connected...
requiring only two angles to describe, for example of a diatomicmolecule. More general molecules are 3-dimensional, such as water (asymmetric rotor), ammonia...
"photonic molecule," whose optical modes bear a strong resemblance to the electronic states of a diatomicmolecule like hydrogen." "Photonic molecules, named...
the binding energy of the molecule. However, this has not yet been detected. The structure of PsH is as a diatomicmolecule, with a chemical bond between...
Carbon monosulfide is a chemical compound with the formula CS. This diatomicmolecule is the sulfur analogue of carbon monoxide, and is unstable as a solid...
microscope. Some of the largest molecules are macromolecules or supermolecules. The smallest molecule is the diatomic hydrogen (H2), with a bond length...
by periodic motion, such as a pendulum, tuning fork, or vibrating diatomicmolecule. Mathematically speaking, the essential feature of an oscillator is...
the diatomicmolecule can be regenerated only with difficulty, but not by normal distillation. Commonly the names of the acid and the molecules are not...
groups containing a triple bond are cyanides and isocyanides. Some diatomicmolecules, such as diphosphorus and carbon monoxide, are also triple bonded...
characteristics of a molecule is its geometry often called its structure. While the structure of diatomic, triatomic or tetra-atomic molecules may be trivial...
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