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Carbyne TEM
In organic chemistry, a carbyne is a general term for any chemical compound, compound whose molecular structure, structure consists of an electric charge, electrically neutral carbon atom connected by a single bond, single covalent bond and has three non-bonded electrons. The carbon atom has either one or three unpaired electrons, depending on its excited state, excitation state; making it a radical (chemistry), radical. The chemical formula can be written or (also written as ), or just CH. Carbynes can be seen as derivatives of the simplest such compound, the methylidyne radical or substitution (chemistry), unsubstituted carbyne or , in which the functional group is a hydrogen atom. Reported for the first time back in 1967 by Kasatochkin, carbyne is an infinite sp1 hybridized long linear chain of carbon, where each link is just a single carbon atom. Electronic configuration Carbyne molecules are generally found to be in electronic doublet states: the non-bonding electrons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbine
A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges. The smaller size and lighter weight of carbines make them easier to handle. They are typically issued to high-mobility troops such as special operations soldiers and paratroopers, as well as to mounted, artillery, logistics, or other non-infantry personnel whose roles do not require full-sized rifles, although there is a growing tendency for carbines to be issued to front-line soldiers to offset the increasing weight of other issued equipment. An example of this is the M4 carbine, the standard issue carbine of the United States Armed Forces. Etymology The name comes from its first users — cavalry troopers called " carabiniers", from the French ''carabine'', from Old French ''carabin'' (soldier armed with a musket), whose origin is unclear. One theory connects ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Orbital
In quantum mechanics, an atomic orbital () is a Function (mathematics), function describing the location and Matter wave, wave-like behavior of an electron in an atom. This function describes an electron's Charge density, charge distribution around the Atomic nucleus, atom's nucleus, and can be used to calculate the probability of finding an electron in a specific region around the nucleus. Each orbital in an atom is characterized by a set of values of three quantum numbers , , and , which respectively correspond to electron's energy, its angular momentum, orbital angular momentum, and its orbital angular momentum projected along a chosen axis (magnetic quantum number). The orbitals with a well-defined magnetic quantum number are generally complex-valued. Real-valued orbitals can be formed as linear combinations of and orbitals, and are often labeled using associated Spherical harmonics#Harmonic polynomial representation, harmonic polynomials (e.g., ''xy'', ) which describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibromofluoromethane
Dibromofluoromethane is a mixed halomethane. It is soluble in alcohol, acetone, benzene and chloroform. It is prepared from dibromomethane and antimony(III) fluoride. Applications It can be used to prepare bromofluoromethane by reductive debromination with organotin hydride as tributyltin hydride. Regulations Its ozone depletion potential The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for examp ... (ODP) is 1.0 and it is included in list of Class I Ozone-Depleting Substances. References {{Halomethanes Halomethanes Bromofluoroalkanes Ozone-depleting chemical substances ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Photolysis
Flash photolysis is a pump-probe laboratory technique, in which a sample is first excited by a strong pulse of light from a pulsed laser of nanosecond, picosecond, or femtosecond pulse width or by another short-pulse light source such as a flash lamp. This first strong pulse is called the pump pulse and starts a chemical reaction or leads to an increased population for energy levels other than the ground state within a sample of atoms or molecules. Typically the absorption of light by the sample is recorded within short time intervals (by a so-called test or probe pulses) to monitor relaxation or reaction processes initiated by the pump pulse. Flash photolysis was developed shortly after World War II as an outgrowth of attempts by military scientists to build cameras fast enough to photograph missiles in flight. The technique was developed in 1949 by Manfred Eigen, Ronald George Wreyford Norrish and George Porter, who won the 1967 Nobel Prize in Chemistry for this invention. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluoromethylidyne
Fluoromethylidyne is not a stable chemical species but a metastable radical containing one highly reactive carbon atom bound to one fluorine atom with the formula CF. The carbon atom has a lone-pair and a single unpaired (radical) electron in the ground state. Ground-state fluoromethylidyne radicals can be produced by the ultraviolet photodissociation of dibromodifluoromethane at 248 nanometer wavelength. It readily and irreversibly dimerises to difluoroacetylene, also known as difluoroethyne, perfluoroacetylene, or di- or perfluoroethylyne. Under certain conditions it can hexamerise to hexafluorobenzene. See also * Carbyne In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three ... References Free radicals Reactive intermediates {{Organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Intermediate
In chemistry, a reactive intermediate or an intermediate is a short-lived, high-energy, highly reactive molecule. When generated in a chemical reaction, it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, matrix isolation. When their existence is indicated, reactive intermediates can help explain how a chemical reaction takes place. Most chemical reactions take more than one elementary step to complete, and a reactive intermediate is a high-energy, hence unstable, product that exists only in one of the intermediate steps. The series of steps together make a reaction mechanism. A reactive intermediate differs from a reactant or product or a simple reaction intermediate only in that it cannot usually be isolated but is sometimes observable only through fast spectroscopic methods. It is stable in the sense that an elementary reaction forms the reactive intermediate and the elementary rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degenerate Energy Levels
In quantum mechanics, an energy level is degenerate if it corresponds to two or more different measurable states of a quantum system. Conversely, two or more different states of a quantum mechanical system are said to be degenerate if they give the same value of energy upon measurement. The number of different states corresponding to a particular energy level is known as the ''degree of degeneracy'' (or simply the ''degeneracy'') of the level. It is represented mathematically by the Hamiltonian for the system having more than one linearly independent eigenstate with the same energy eigenvalue. When this is the case, energy alone is not enough to characterize what state the system is in, and other quantum numbers are needed to characterize the exact state when distinction is desired. In classical mechanics, this can be understood in terms of different possible trajectories corresponding to the same energy. Degeneracy plays a fundamental role in quantum statistical mechanics. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoelectronic
Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in the structure. For example, , , and are isoelectronic, while and = are not. This definition is sometimes termed valence isoelectronicity. Definitions can sometimes be not as strict, sometimes requiring identity of the total electron count and with it the entire electronic configuration. More usually, definitions are broader, and may extend to allowing different numbers of atoms in the species being compared.A. A. Aradi & T. P. Fehlner, "Isoelectronic Organometallic Molecules", in F. G. A. Stone & Robert West (eds.) ''Advances in Organometallic Chemistry Vol. 30'' (1990), Chapter 5 (at p. 190google books link/ref> The importance of the concept lies in identifying significantly related species, as pairs or series. Isoelectronic specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-bonding Orbital
A non-bonding orbital, also known as ''non-bonding molecular orbital'' (NBMO), is a molecular orbital whose occupation by electrons neither increases nor decreases the bond order between the involved atoms. Non-bonding orbitals are often designated by the letter n in molecular orbital diagrams and electron transition notations. Non-bonding orbitals are the equivalent in molecular orbital theory of the lone pairs in Lewis structures. The energy level of a non-bonding orbital is typically in between the lower energy of a valence shell bonding orbital and the higher energy of a corresponding antibonding orbital. As such, a non-bonding orbital with electrons would commonly be a HOMO ( highest occupied molecular orbital). According to molecular orbital theory, molecular orbitals are often modeled by the linear combination of atomic orbitals. In a simple diatomic molecule such as hydrogen fluoride (chemical formula: HF), one atom may have many more electrons than the other. A sigm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Hybridisation
In chemistry, orbital hybridisation (or hybridization) is the concept of mixing atomic orbitals to form new ''hybrid orbitals'' (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory. For example, in a carbon atom which forms four single bonds, the valence-shell s orbital combines with three valence-shell p orbitals to form four equivalent sp3 mixtures in a tetrahedral arrangement around the carbon to bond to four different atoms. Hybrid orbitals are useful in the explanation of molecular geometry and atomic bonding properties and are symmetrically disposed in space. Usually hybrid orbitals are formed by mixing atomic orbitals of comparable energies. History and uses Chemist Linus Pauling first developed the hybridisation theory in 1931 to explain the structure of simple molecules such as methane (CH4) using atomic orbitals. Pauling pointed out that a carbon atom forms four ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Overlap
In chemical bonds, an orbital overlap is the concentration of orbitals on adjacent atoms in the same regions of space. Orbital overlap can lead to bond formation. The general principle for orbital overlap is that, the greater the overlap between orbitals, the greater the bond strength. Linus Pauling explained the importance of orbital overlap in the molecular bond angles observed through experimentation; it is the basis for orbital hybridization. As ''s'' orbitals are spherical (and have no directionality) and ''p'' orbitals are oriented 90° to each other, a theory was needed to explain why molecules such as methane (CH4) had observed bond angles of 109.5°. Pauling proposed that s and p orbitals on the carbon atom can combine to form hybrids (sp3 in the case of methane) which are directed toward the hydrogen atoms. The carbon hybrid orbitals have greater overlap with the hydrogen orbitals, and can therefore form stronger C–H bonds.Pauling, Linus. (1960). ''The Nature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
