Matches in DBpedia 2016-04 for { ?s ?p "In organic chemistry, Hückel's rule estimates whether a planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. The succinct expression as the 4n+2 rule has been attributed to von Doering (1951), although several authors were using this form at around the same time.A cyclic ring molecule follows Hückel's rule when the number of its π-electrons equals 4n+2 where n is zero or any positive integer, although clearcut examples are really only established for values of n = 0 up to about n = 6. Hückel's rule was originally based on calculations using the Hückel method, although it can also be justified by considering a particle in a ring system, by the LCAO method and by the Pariser–Parr–Pople method.Aromatic compounds are more stable than theoretically predicted by alkene hydrogenation data; the \"extra\" stability is due to the delocalized cloud of electrons, called resonance energy. Criteria for simple aromatics are: the molecule must follow Hückel's rule, having 4n+2 electrons in the delocalized, conjugated p-orbital cloud; the molecule must be able to be planar; the molecule must be cyclic; and, every atom in the ring must be able to participate in delocalizing the electrons by having a p-orbital or an unshared pair of electrons.↑ ↑ ↑ ↑ ↑ ↑"@en }
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- Hxc3xbcckels_rule abstract "In organic chemistry, Hückel's rule estimates whether a planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. The succinct expression as the 4n+2 rule has been attributed to von Doering (1951), although several authors were using this form at around the same time.A cyclic ring molecule follows Hückel's rule when the number of its π-electrons equals 4n+2 where n is zero or any positive integer, although clearcut examples are really only established for values of n = 0 up to about n = 6. Hückel's rule was originally based on calculations using the Hückel method, although it can also be justified by considering a particle in a ring system, by the LCAO method and by the Pariser–Parr–Pople method.Aromatic compounds are more stable than theoretically predicted by alkene hydrogenation data; the \"extra\" stability is due to the delocalized cloud of electrons, called resonance energy. Criteria for simple aromatics are: the molecule must follow Hückel's rule, having 4n+2 electrons in the delocalized, conjugated p-orbital cloud; the molecule must be able to be planar; the molecule must be cyclic; and, every atom in the ring must be able to participate in delocalizing the electrons by having a p-orbital or an unshared pair of electrons.↑ ↑ ↑ ↑ ↑ ↑".