Physics:Quantum chemical bond - Revision history

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	~~{{Quantum article nav\|previous=Physics:Quantum molecular structure\|previous label=Molecular structure\|next=Physics:Quantum molecular orbital\|next label=Molecular orbital}}~~



	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}
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	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}I		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}

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	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}~~Book II~~		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}I

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	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}Book II

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	'''Chemical bond''' is the association of ~~[[Physics:Quantum~~ atoms~~\|atoms]]~~ or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their ~~[[Physics:Quantum wavefunction\|~~wavefunctions]], and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].		'''Chemical bond''' is the association of atoms or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their wavefunctions, and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].

	A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=Journal of the American Chemical Society \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>		A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=Journal of the American Chemical Society \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>

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	'''Chemical bond''' is the association of [[Physics:Quantum atoms\|atoms]] or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their [[Physics:Quantum wavefunction\|wavefunctions]], and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].		'''Chemical bond''' is the association of [[Physics:Quantum atoms\|atoms]] or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their [[Physics:Quantum wavefunction\|wavefunctions]], and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].

	A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=[[Journal of the American Chemical Society]] \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>		A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=Journal of the American Chemical Society \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>

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	Early chemical theory developed before atoms were fully understood. Robert Boyle, Antoine Lavoisier, Joseph Proust, Humphry Davy, Jöns Jakob Berzelius, Edward Frankland, August Kekulé, A. S. Couper, Alexander Butlerov, Hermann Kolbe, and Richard Abegg contributed to ideas about elements, compounds, valency, and chemical combination.<ref name="Whittaker">{{Cite book \|last=Whittaker \|first=Edmund T. \|title=A history of the theories of aether & electricity. 1: The classical theories \|date=1989 \|publisher=Dover Publ \|isbn=978-0-486-26126-3 \|edition=Repr \|location=New York}}</ref><ref name=Pullman-1998>{{cite book\|last1=Pullman\|first1=Bernard\|title=The Atom in the History of Human Thought\|date=1998\|publisher=Oxford University Press\|location=Oxford, England\|isbn=978-0-19-515040-7\|pages=31–33\|url=https://books.google.com/books?id=IQs5hur-BpgC&\|access-date=25 October 2020\|archive-date=5 February 2021\|archive-url=https://web.archive.org/web/20210205165029/https://books.google.com/books?id=IQs5hur-BpgC&q=Leucippus+Democritus+atom&pg=PA56\|url-status=live}}</ref><ref>{{Cite web\|title=Law of definite proportions {{!}} chemistry\|url=https://www.britannica.com/science/law-of-definite-proportions\|access-date=2020-09-03\|website=Encyclopedia Britannica\|language=en}}</ref><ref name=Hudson-1992>{{Cite book \|last=Hudson \|first=John \|url=http://link.springer.com/10.1007/978-1-4684-6441-2 \|title=The History of Chemistry \|date=1992 \|publisher=Springer US \|isbn=978-1-4684-6443-6 \|location=Boston, MA \|language=en \|doi=10.1007/978-1-4684-6441-2}}</ref><ref>{{cite journal \|last1=Frankland \|first1=E. \|year=1852 \|title=On a New Series of Organic Bodies Containing Metals \|journal=Philosophical Transactions of the Royal Society of London \|volume=142 \|pages=417–444 \|doi=10.1098/rstl.1852.0020 \|s2cid=186210604}}</ref><ref>{{Cite journal \|last=Abegg \|first=R. \|year=1904 \|title=Die Valenz und das periodische System. Versuch einer Theorie der Molekularverbindungen \|trans-title=Valency and the periodic table. Attempt at a theory of molecular compounds \|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3959087;view=1up;seq=344 \|journal=Zeitschrift für anorganische Chemie \|language=German \|volume=39 \|issue=1 \|pages=330–380 \|doi=10.1002/zaac.19040390125}}</ref>		Early chemical theory developed before atoms were fully understood. Robert Boyle, Antoine Lavoisier, Joseph Proust, Humphry Davy, Jöns Jakob Berzelius, Edward Frankland, August Kekulé, A. S. Couper, Alexander Butlerov, Hermann Kolbe, and Richard Abegg contributed to ideas about elements, compounds, valency, and chemical combination.<ref name="Whittaker">{{Cite book \|last=Whittaker \|first=Edmund T. \|title=A history of the theories of aether & electricity. 1: The classical theories \|date=1989 \|publisher=Dover Publ \|isbn=978-0-486-26126-3 \|edition=Repr \|location=New York}}</ref><ref name=Pullman-1998>{{cite book\|last1=Pullman\|first1=Bernard\|title=The Atom in the History of Human Thought\|date=1998\|publisher=Oxford University Press\|location=Oxford, England\|isbn=978-0-19-515040-7\|pages=31–33\|url=https://books.google.com/books?id=IQs5hur-BpgC&\|access-date=25 October 2020\|archive-date=5 February 2021\|archive-url=https://web.archive.org/web/20210205165029/https://books.google.com/books?id=IQs5hur-BpgC&q=Leucippus+Democritus+atom&pg=PA56\|url-status=live}}</ref><ref>{{Cite web\|title=Law of definite proportions {{!}} chemistry\|url=https://www.britannica.com/science/law-of-definite-proportions\|access-date=2020-09-03\|website=Encyclopedia Britannica\|language=en}}</ref><ref name=Hudson-1992>{{Cite book \|last=Hudson \|first=John \|url=http://link.springer.com/10.1007/978-1-4684-6441-2 \|title=The History of Chemistry \|date=1992 \|publisher=Springer US \|isbn=978-1-4684-6443-6 \|location=Boston, MA \|language=en \|doi=10.1007/978-1-4684-6441-2}}</ref><ref>{{cite journal \|last1=Frankland \|first1=E. \|year=1852 \|title=On a New Series of Organic Bodies Containing Metals \|journal=Philosophical Transactions of the Royal Society of London \|volume=142 \|pages=417–444 \|doi=10.1098/rstl.1852.0020 \|s2cid=186210604}}</ref><ref>{{Cite journal \|last=Abegg \|first=R. \|year=1904 \|title=Die Valenz und das periodische System. Versuch einer Theorie der Molekularverbindungen \|trans-title=Valency and the periodic table. Attempt at a theory of molecular compounds \|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3959087;view=1up;seq=344 \|journal=Zeitschrift für anorganische Chemie \|language=German \|volume=39 \|issue=1 \|pages=330–380 \|doi=10.1002/zaac.19040390125}}</ref>

	The nuclear atom and the role of electrons became clearer through the work of Hantaro Nagaoka, Ernest Rutherford, Max Planck, and Niels Bohr.<ref>The Genesis of the Bohr Atom, John L. Heilbron and Thomas S. Kuhn, Historical Studies in the Physical Sciences, Vol. 1 (1969), pp. vi, 211-290 (81 pages), University of California Press.</ref><ref>{{cite book \|author=B. Bryson \|title=A Short History of Nearly Everything \|title-link=A Short History of Nearly Everything \|publisher=[[Broadway Books]] \|year=2003 \|isbn=0-7679-0817-1 \|author-link=Bill Bryson }}</ref><ref>Original Proceedings of the 1911 Solvay Conference published 1912. THÉORIE DU RAYONNEMENT ET LES QUANTA. RAPPORTS ET DISCUSSIONS DELA Réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911, Sous les Auspices dk M. E. SOLVAY. Publiés par MM. P. LANGEVIN et M. de BROGLIE. Translated from the French, p. 127.</ref>		The nuclear atom and the role of electrons became clearer through the work of Hantaro Nagaoka, Ernest Rutherford, Max Planck, and Niels Bohr.<ref>The Genesis of the Bohr Atom, John L. Heilbron and Thomas S. Kuhn, Historical Studies in the Physical Sciences, Vol. 1 (1969), pp. vi, 211-290 (81 pages), University of California Press.</ref><ref>{{cite book \|author=B. Bryson \|title=A Short History of Nearly Everything \|title-link=A Short History of Nearly Everything \|publisher=Broadway Books \|year=2003 \|isbn=0-7679-0817-1 \|author-link=Bill Bryson }}</ref><ref>Original Proceedings of the 1911 Solvay Conference published 1912. THÉORIE DU RAYONNEMENT ET LES QUANTA. RAPPORTS ET DISCUSSIONS DELA Réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911, Sous les Auspices dk M. E. SOLVAY. Publiés par MM. P. LANGEVIN et M. de BROGLIE. Translated from the French, p. 127.</ref>

	In 1916 Gilbert N. Lewis introduced the electron-pair bond model, while Walther Kossel developed an ionic bonding model. Bohr also proposed an early model of chemical bonding.<ref>{{cite journal\|last=Lewis\|first=Gilbert N.\|author-link=Gilbert N. Lewis\|year=1916\|title=The Atom and the Molecule\|journal=[[Journal of the American Chemical Society]]\|volume=38\|page=772\|url=http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/papers/corr216.3-lewispub-19160400.html\|doi=10.1021/ja02261a002\|issue=4\|bibcode=1916JAChS..38..762L \|s2cid=95865413\|url-access=subscription}} [http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 a copy] {{Webarchive\|url=https://web.archive.org/web/20210418014936/http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 \|date=2021-04-18 }}</ref><ref name="Pais">{{Cite book\|last=Pais\|first=Abraham \|year=1986\|location=New York\|title=Inward Bound: Of Matter and Forces in the Physical World\|publisher=Oxford University Press\|isbn=978-0-19-851971-3\|pages=[https://archive.org/details/inwardboundofmat00pais_0/page/228 228–230]\|url=https://archive.org/details/inwardboundofmat00pais_0/page/228}}</ref><ref>{{cite journal\|last=Svidzinsky\|first=Anatoly A. \|author2=Marlan O. Scully \|author3-link=Dudley R. Herschbach \|author3=Dudley R. Herschbach\|year=2005\|title=Bohr's 1913 molecular model revisited \|journal=Proceedings of the National Academy of Sciences \|volume=102\|pages=11985–11988\|doi=10.1073/pnas.0505778102 \|pmid=16103360 \|pmc=1186029 \|issue=34\|arxiv=physics/0508161\|bibcode=2005PNAS..10211985S\|doi-access=free \|url=http://www.pnas.org/content/102/34/11985.full.pdf \|archive-url=https://web.archive.org/web/20180718233029/http://www.pnas.org/content/102/34/11985.full.pdf \|archive-date=2018-07-18 \|url-status=live}}</ref>		In 1916 Gilbert N. Lewis introduced the electron-pair bond model, while Walther Kossel developed an ionic bonding model. Bohr also proposed an early model of chemical bonding.<ref>{{cite journal\|last=Lewis\|first=Gilbert N.\|author-link=Gilbert N. Lewis\|year=1916\|title=The Atom and the Molecule\|journal=Journal of the American Chemical Society\|volume=38\|page=772\|url=http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/papers/corr216.3-lewispub-19160400.html\|doi=10.1021/ja02261a002\|issue=4\|bibcode=1916JAChS..38..762L \|s2cid=95865413\|url-access=subscription}} [http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 a copy] {{Webarchive\|url=https://web.archive.org/web/20210418014936/http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 \|date=2021-04-18 }}</ref><ref name="Pais">{{Cite book\|last=Pais\|first=Abraham \|year=1986\|location=New York\|title=Inward Bound: Of Matter and Forces in the Physical World\|publisher=Oxford University Press\|isbn=978-0-19-851971-3\|pages=[https://archive.org/details/inwardboundofmat00pais_0/page/228 228–230]\|url=https://archive.org/details/inwardboundofmat00pais_0/page/228}}</ref><ref>{{cite journal\|last=Svidzinsky\|first=Anatoly A. \|author2=Marlan O. Scully \|author3-link=Dudley R. Herschbach \|author3=Dudley R. Herschbach\|year=2005\|title=Bohr's 1913 molecular model revisited \|journal=Proceedings of the National Academy of Sciences \|volume=102\|pages=11985–11988\|doi=10.1073/pnas.0505778102 \|pmid=16103360 \|pmc=1186029 \|issue=34\|arxiv=physics/0508161\|bibcode=2005PNAS..10211985S\|doi-access=free \|url=http://www.pnas.org/content/102/34/11985.full.pdf \|archive-url=https://web.archive.org/web/20180718233029/http://www.pnas.org/content/102/34/11985.full.pdf \|archive-date=2018-07-18 \|url-status=live}}</ref>

	In 1927 Øyvind Burrau gave a quantum treatment of the hydrogen molecular ion, and Walter Heitler and Fritz London developed the approach that became valence bond theory.<ref>{{cite book\| author=Laidler, K. J. \|year=1993\|title=The World of Physical Chemistry\| url=https://archive.org/details/worldofphysicalc0000laid \| url-access=registration \|publisher=Oxford University Press \| page=[https://archive.org/details/worldofphysicalc0000laid/page/346 346]\|isbn=978-0-19-855919-1}}</ref><ref name="London">{{cite journal\|first1=W. \|last1=Heitler \|first2=F. \|last2=London \|title=Wechselwirkung neutraler Atome und homoopolare Bindung nach der Quantenmechanik \|trans-title=Interaction of neutral atoms and homeopolar bonds according to quantum mechanics \|journal=Zeitschrift für Physik \|volume=44 \|issue=6–7 \|pages=455–472 \|date=1927 \|doi=10.1007/bf01397394 \|bibcode=1927ZPhy...44..455H \|s2cid=119739102}} English translation in {{cite book\| last=Hettema\| first=H.\| title=Quantum Chemistry: Classic Scientific Papers\| url=https://books.google.com/books?id=qsidHRJmUoIC\| access-date=2012-02-05\| year=2000\| publisher=World Scientific\| isbn=978-981-02-2771-5\| pages=140}}</ref> Molecular orbital theory, LCAO methods, and later density functional theory became major tools in quantum chemistry.<ref>{{cite journal \| last=James \| first=H.H. \|author2=Coolidge, A S. \| title=The Ground State of the Hydrogen Molecule \| journal=[[Journal of Chemical Physics]] \| volume=1 \| issue=12 \| pages=825–835 \| year=1933 \| doi=10.1063/1.1749252 \| bibcode=1933JChPh...1..825J }}</ref>		In 1927 Øyvind Burrau gave a quantum treatment of the hydrogen molecular ion, and Walter Heitler and Fritz London developed the approach that became valence bond theory.<ref>{{cite book\| author=Laidler, K. J. \|year=1993\|title=The World of Physical Chemistry\| url=https://archive.org/details/worldofphysicalc0000laid \| url-access=registration \|publisher=Oxford University Press \| page=[https://archive.org/details/worldofphysicalc0000laid/page/346 346]\|isbn=978-0-19-855919-1}}</ref><ref name="London">{{cite journal\|first1=W. \|last1=Heitler \|first2=F. \|last2=London \|title=Wechselwirkung neutraler Atome und homoopolare Bindung nach der Quantenmechanik \|trans-title=Interaction of neutral atoms and homeopolar bonds according to quantum mechanics \|journal=Zeitschrift für Physik \|volume=44 \|issue=6–7 \|pages=455–472 \|date=1927 \|doi=10.1007/bf01397394 \|bibcode=1927ZPhy...44..455H \|s2cid=119739102}} English translation in {{cite book\| last=Hettema\| first=H.\| title=Quantum Chemistry: Classic Scientific Papers\| url=https://books.google.com/books?id=qsidHRJmUoIC\| access-date=2012-02-05\| year=2000\| publisher=World Scientific\| isbn=978-981-02-2771-5\| pages=140}}</ref> Molecular orbital theory, LCAO methods, and later density functional theory became major tools in quantum chemistry.<ref>{{cite journal \| last=James \| first=H.H. \|author2=Coolidge, A S. \| title=The Ground State of the Hydrogen Molecule \| journal=Journal of Chemical Physics \| volume=1 \| issue=12 \| pages=825–835 \| year=1933 \| doi=10.1063/1.1749252 \| bibcode=1933JChPh...1..825J }}</ref>

	== Bond energies and lengths ==		== Bond energies and lengths ==

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	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}Book II

	{{Quantum matter backlink\|Molecules}}		{{Quantum matter backlink\|Molecules}}

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	{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}		{{Short description\|Quantum-mechanical association of atoms into molecules and matter}}

	{{Quantum matter backlink\|Molecules}}		{{Quantum matter backlink\|Molecules}}
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	'''Chemical bond''' is the association of [[Physics:Quantum atoms\|atoms]] or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their [[Physics:Quantum wavefunction\|wavefunctions]], and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].		'''Chemical bond''' is the association of [[Physics:Quantum atoms\|atoms]] or [[Physics:Quantum atoms/ion\|ions]] into [[Physics:Quantum molecular structure\|molecules]], crystals, metals, and other forms of matter. In quantum physics, bonding is explained by the behavior of [[Physics:Quantum atoms/electron\|electrons]], their [[Physics:Quantum wavefunction\|wavefunctions]], and the allowed [[Physics:Quantum atoms/orbital\|atomic orbitals]] and [[Physics:Quantum atoms/orbital\|molecular orbitals]].

	A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=[[Journal of the American Chemical Society]] \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>		A chemical bond may result from electrostatic attraction between oppositely charged ions, as in ionic bonding, or from the sharing and delocalization of electrons, as in covalent and metallic bonding. In a quantum description, constructive wavefunction interference can stabilize two nuclei by forming a lower-energy electronic state.<ref name="Levine Head-Gordon 2020 p. ">{{cite journal \| last1=Levine \| first1=Daniel S. \| last2=Head-Gordon \| first2=Martin \| title=Clarifying the quantum mechanical origin of the covalent chemical bond \| journal=Nature Communications \| publisher=Springer Science and Business Media LLC \| volume=11 \| issue=1 \| date=2020-09-29 \| issn=2041-1723 \| doi=10.1038/s41467-020-18670-8 \| page=4893\| pmid=32994392 \| pmc=7524788 \| bibcode=2020NatCo..11.4893L \| s2cid=222157102 }}</ref> The equilibrium bond distance reflects a balance between attractive and repulsive interactions that can be treated quantitatively by quantum theory.<ref>{{citation \| last=Pauling \| first=L. \| year=1931 \| title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules \| journal=Journal of the American Chemical Society \| volume=53 \| issue=4 \| pages=1367–1400 \| doi=10.1021/ja01355a027 \| bibcode=1931JAChS..53.1367P }}</ref><ref>{{Cite journal \|last=Hund \|first=F. \|date=1928 \|title=Zur Deutung der Molekelspektren. IV \|url=http://link.springer.com/10.1007/BF01400239 \|journal=Zeitschrift für Physik \|language=de \|volume=51 \|issue=11–12 \|pages=759–795 \|doi=10.1007/BF01400239 \|bibcode=1928ZPhy...51..759H \|s2cid=121366097 \|issn=1434-6001\|url-access=subscription }}</ref>

	</div>		</div>
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	Early chemical theory developed before atoms were fully understood. Robert Boyle, Antoine Lavoisier, Joseph Proust, Humphry Davy, Jöns Jakob Berzelius, Edward Frankland, August Kekulé, A. S. Couper, Alexander Butlerov, Hermann Kolbe, and Richard Abegg contributed to ideas about elements, compounds, valency, and chemical combination.<ref name="Whittaker">{{Cite book \|last=Whittaker \|first=Edmund T. \|title=A history of the theories of aether & electricity. 1: The classical theories \|date=1989 \|publisher=Dover Publ \|isbn=978-0-486-26126-3 \|edition=Repr \|location=New York}}</ref><ref name=Pullman-1998>{{cite book\|last1=Pullman\|first1=Bernard\|title=The Atom in the History of Human Thought\|date=1998\|publisher=Oxford University Press\|location=Oxford, England\|isbn=978-0-19-515040-7\|pages=31–33\|url=https://books.google.com/books?id=IQs5hur-BpgC&\|access-date=25 October 2020\|archive-date=5 February 2021\|archive-url=https://web.archive.org/web/20210205165029/https://books.google.com/books?id=IQs5hur-BpgC&q=Leucippus+Democritus+atom&pg=PA56\|url-status=live}}</ref><ref>{{Cite web\|title=Law of definite proportions {{!}} chemistry\|url=https://www.britannica.com/science/law-of-definite-proportions\|access-date=2020-09-03\|website=Encyclopedia Britannica\|language=en}}</ref><ref name=Hudson-1992>{{Cite book \|last=Hudson \|first=John \|url=http://link.springer.com/10.1007/978-1-4684-6441-2 \|title=The History of Chemistry \|date=1992 \|publisher=Springer US \|isbn=978-1-4684-6443-6 \|location=Boston, MA \|language=en \|doi=10.1007/978-1-4684-6441-2}}</ref><ref>{{cite journal \|last1=Frankland \|first1=E. \|year=1852 \|title=On a New Series of Organic Bodies Containing Metals \|journal=Philosophical Transactions of the Royal Society of London \|volume=142 \|pages=417–444 \|doi=10.1098/rstl.1852.0020 \|s2cid=186210604}}</ref><ref>{{Cite journal \|last=Abegg \|first=R. \|year=1904 \|title=Die Valenz und das periodische System. Versuch einer Theorie der Molekularverbindungen \|trans-title=Valency and the periodic table. Attempt at a theory of molecular compounds \|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3959087;view=1up;seq=344 \|journal=Zeitschrift für anorganische Chemie \|language=German \|volume=39 \|issue=1 \|pages=330–380 \|doi=10.1002/zaac.19040390125}}</ref>		Early chemical theory developed before atoms were fully understood. Robert Boyle, Antoine Lavoisier, Joseph Proust, Humphry Davy, Jöns Jakob Berzelius, Edward Frankland, August Kekulé, A. S. Couper, Alexander Butlerov, Hermann Kolbe, and Richard Abegg contributed to ideas about elements, compounds, valency, and chemical combination.<ref name="Whittaker">{{Cite book \|last=Whittaker \|first=Edmund T. \|title=A history of the theories of aether & electricity. 1: The classical theories \|date=1989 \|publisher=Dover Publ \|isbn=978-0-486-26126-3 \|edition=Repr \|location=New York}}</ref><ref name=Pullman-1998>{{cite book\|last1=Pullman\|first1=Bernard\|title=The Atom in the History of Human Thought\|date=1998\|publisher=Oxford University Press\|location=Oxford, England\|isbn=978-0-19-515040-7\|pages=31–33\|url=https://books.google.com/books?id=IQs5hur-BpgC&\|access-date=25 October 2020\|archive-date=5 February 2021\|archive-url=https://web.archive.org/web/20210205165029/https://books.google.com/books?id=IQs5hur-BpgC&q=Leucippus+Democritus+atom&pg=PA56\|url-status=live}}</ref><ref>{{Cite web\|title=Law of definite proportions {{!}} chemistry\|url=https://www.britannica.com/science/law-of-definite-proportions\|access-date=2020-09-03\|website=Encyclopedia Britannica\|language=en}}</ref><ref name=Hudson-1992>{{Cite book \|last=Hudson \|first=John \|url=http://link.springer.com/10.1007/978-1-4684-6441-2 \|title=The History of Chemistry \|date=1992 \|publisher=Springer US \|isbn=978-1-4684-6443-6 \|location=Boston, MA \|language=en \|doi=10.1007/978-1-4684-6441-2}}</ref><ref>{{cite journal \|last1=Frankland \|first1=E. \|year=1852 \|title=On a New Series of Organic Bodies Containing Metals \|journal=Philosophical Transactions of the Royal Society of London \|volume=142 \|pages=417–444 \|doi=10.1098/rstl.1852.0020 \|s2cid=186210604}}</ref><ref>{{Cite journal \|last=Abegg \|first=R. \|year=1904 \|title=Die Valenz und das periodische System. Versuch einer Theorie der Molekularverbindungen \|trans-title=Valency and the periodic table. Attempt at a theory of molecular compounds \|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3959087;view=1up;seq=344 \|journal=Zeitschrift für anorganische Chemie \|language=German \|volume=39 \|issue=1 \|pages=330–380 \|doi=10.1002/zaac.19040390125}}</ref>

	The nuclear atom and the role of electrons became clearer through the work of Hantaro Nagaoka, Ernest Rutherford, Max Planck, and Niels Bohr.<ref>The Genesis of the Bohr Atom, John L. Heilbron and Thomas S. Kuhn, Historical Studies in the Physical Sciences, Vol. 1 (1969), pp. vi, 211-290 (81 pages), University of California Press.</ref><ref>{{cite book \|author=B. Bryson \|title=A Short History of Nearly Everything \|title-link=A Short History of Nearly Everything \|publisher=[[Broadway Books]] \|year=2003 \|isbn=0-7679-0817-1 \|author-link=Bill Bryson }}</ref><ref>Original Proceedings of the 1911 Solvay Conference published 1912. THÉORIE DU RAYONNEMENT ET LES QUANTA. RAPPORTS ET DISCUSSIONS DELA Réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911, Sous les Auspices dk M. E. SOLVAY. Publiés par MM. P. LANGEVIN et M. de BROGLIE. Translated from the French, p. 127.</ref>		The nuclear atom and the role of electrons became clearer through the work of Hantaro Nagaoka, Ernest Rutherford, Max Planck, and Niels Bohr.<ref>The Genesis of the Bohr Atom, John L. Heilbron and Thomas S. Kuhn, Historical Studies in the Physical Sciences, Vol. 1 (1969), pp. vi, 211-290 (81 pages), University of California Press.</ref><ref>{{cite book \|author=B. Bryson \|title=A Short History of Nearly Everything \|title-link=A Short History of Nearly Everything \|publisher=Broadway Books \|year=2003 \|isbn=0-7679-0817-1 \|author-link=Bill Bryson }}</ref><ref>Original Proceedings of the 1911 Solvay Conference published 1912. THÉORIE DU RAYONNEMENT ET LES QUANTA. RAPPORTS ET DISCUSSIONS DELA Réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911, Sous les Auspices dk M. E. SOLVAY. Publiés par MM. P. LANGEVIN et M. de BROGLIE. Translated from the French, p. 127.</ref>

	In 1916 Gilbert N. Lewis introduced the electron-pair bond model, while Walther Kossel developed an ionic bonding model. Bohr also proposed an early model of chemical bonding.<ref>{{cite journal\|last=Lewis\|first=Gilbert N.\|author-link=Gilbert N. Lewis\|year=1916\|title=The Atom and the Molecule\|journal=[[Journal of the American Chemical Society]]\|volume=38\|page=772\|url=http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/papers/corr216.3-lewispub-19160400.html\|doi=10.1021/ja02261a002\|issue=4\|bibcode=1916JAChS..38..762L \|s2cid=95865413\|url-access=subscription}} [http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 a copy] {{Webarchive\|url=https://web.archive.org/web/20210418014936/http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 \|date=2021-04-18 }}</ref><ref name="Pais">{{Cite book\|last=Pais\|first=Abraham \|year=1986\|location=New York\|title=Inward Bound: Of Matter and Forces in the Physical World\|publisher=Oxford University Press\|isbn=978-0-19-851971-3\|pages=[https://archive.org/details/inwardboundofmat00pais_0/page/228 228–230]\|url=https://archive.org/details/inwardboundofmat00pais_0/page/228}}</ref><ref>{{cite journal\|last=Svidzinsky\|first=Anatoly A. \|author2=Marlan O. Scully \|author3-link=Dudley R. Herschbach \|author3=Dudley R. Herschbach\|year=2005\|title=Bohr's 1913 molecular model revisited \|journal=Proceedings of the National Academy of Sciences \|volume=102\|pages=11985–11988\|doi=10.1073/pnas.0505778102 \|pmid=16103360 \|pmc=1186029 \|issue=34\|arxiv=physics/0508161\|bibcode=2005PNAS..10211985S\|doi-access=free \|url=http://www.pnas.org/content/102/34/11985.full.pdf \|archive-url=https://web.archive.org/web/20180718233029/http://www.pnas.org/content/102/34/11985.full.pdf \|archive-date=2018-07-18 \|url-status=live}}</ref>		In 1916 Gilbert N. Lewis introduced the electron-pair bond model, while Walther Kossel developed an ionic bonding model. Bohr also proposed an early model of chemical bonding.<ref>{{cite journal\|last=Lewis\|first=Gilbert N.\|author-link=Gilbert N. Lewis\|year=1916\|title=The Atom and the Molecule\|journal=Journal of the American Chemical Society\|volume=38\|page=772\|url=http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/papers/corr216.3-lewispub-19160400.html\|doi=10.1021/ja02261a002\|issue=4\|bibcode=1916JAChS..38..762L \|s2cid=95865413\|url-access=subscription}} [http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 a copy] {{Webarchive\|url=https://web.archive.org/web/20210418014936/http://www.itis.arezzo.it/index.php?option=com_content&view=article&id=221%3Athe-atom-and-the-molecule-&catid=106%3Apagine-html&Itemid=98 \|date=2021-04-18 }}</ref><ref name="Pais">{{Cite book\|last=Pais\|first=Abraham \|year=1986\|location=New York\|title=Inward Bound: Of Matter and Forces in the Physical World\|publisher=Oxford University Press\|isbn=978-0-19-851971-3\|pages=[https://archive.org/details/inwardboundofmat00pais_0/page/228 228–230]\|url=https://archive.org/details/inwardboundofmat00pais_0/page/228}}</ref><ref>{{cite journal\|last=Svidzinsky\|first=Anatoly A. \|author2=Marlan O. Scully \|author3-link=Dudley R. Herschbach \|author3=Dudley R. Herschbach\|year=2005\|title=Bohr's 1913 molecular model revisited \|journal=Proceedings of the National Academy of Sciences \|volume=102\|pages=11985–11988\|doi=10.1073/pnas.0505778102 \|pmid=16103360 \|pmc=1186029 \|issue=34\|arxiv=physics/0508161\|bibcode=2005PNAS..10211985S\|doi-access=free \|url=http://www.pnas.org/content/102/34/11985.full.pdf \|archive-url=https://web.archive.org/web/20180718233029/http://www.pnas.org/content/102/34/11985.full.pdf \|archive-date=2018-07-18 \|url-status=live}}</ref>

	In 1927 Øyvind Burrau gave a quantum treatment of the hydrogen molecular ion, and Walter Heitler and Fritz London developed the approach that became valence bond theory.<ref>{{cite book\| author=Laidler, K. J. \|year=1993\|title=The World of Physical Chemistry\| url=https://archive.org/details/worldofphysicalc0000laid \| url-access=registration \|publisher=Oxford University Press \| page=[https://archive.org/details/worldofphysicalc0000laid/page/346 346]\|isbn=978-0-19-855919-1}}</ref><ref name="London">{{cite journal\|first1=W. \|last1=Heitler \|first2=F. \|last2=London \|title=Wechselwirkung neutraler Atome und homoopolare Bindung nach der Quantenmechanik \|trans-title=Interaction of neutral atoms and homeopolar bonds according to quantum mechanics \|journal=Zeitschrift für Physik \|volume=44 \|issue=6–7 \|pages=455–472 \|date=1927 \|doi=10.1007/bf01397394 \|bibcode=1927ZPhy...44..455H \|s2cid=119739102}} English translation in {{cite book\| last=Hettema\| first=H.\| title=Quantum Chemistry: Classic Scientific Papers\| url=https://books.google.com/books?id=qsidHRJmUoIC\| access-date=2012-02-05\| year=2000\| publisher=World Scientific\| isbn=978-981-02-2771-5\| pages=140}}</ref> Molecular orbital theory, LCAO methods, and later density functional theory became major tools in quantum chemistry.<ref>{{cite journal \| last=James \| first=H.H. \|author2=Coolidge, A S. \| title=The Ground State of the Hydrogen Molecule \| journal=[[Journal of Chemical Physics]] \| volume=1 \| issue=12 \| pages=825–835 \| year=1933 \| doi=10.1063/1.1749252 \| bibcode=1933JChPh...1..825J }}</ref>		In 1927 Øyvind Burrau gave a quantum treatment of the hydrogen molecular ion, and Walter Heitler and Fritz London developed the approach that became valence bond theory.<ref>{{cite book\| author=Laidler, K. J. \|year=1993\|title=The World of Physical Chemistry\| url=https://archive.org/details/worldofphysicalc0000laid \| url-access=registration \|publisher=Oxford University Press \| page=[https://archive.org/details/worldofphysicalc0000laid/page/346 346]\|isbn=978-0-19-855919-1}}</ref><ref name="London">{{cite journal\|first1=W. \|last1=Heitler \|first2=F. \|last2=London \|title=Wechselwirkung neutraler Atome und homoopolare Bindung nach der Quantenmechanik \|trans-title=Interaction of neutral atoms and homeopolar bonds according to quantum mechanics \|journal=Zeitschrift für Physik \|volume=44 \|issue=6–7 \|pages=455–472 \|date=1927 \|doi=10.1007/bf01397394 \|bibcode=1927ZPhy...44..455H \|s2cid=119739102}} English translation in {{cite book\| last=Hettema\| first=H.\| title=Quantum Chemistry: Classic Scientific Papers\| url=https://books.google.com/books?id=qsidHRJmUoIC\| access-date=2012-02-05\| year=2000\| publisher=World Scientific\| isbn=978-981-02-2771-5\| pages=140}}</ref> Molecular orbital theory, LCAO methods, and later density functional theory became major tools in quantum chemistry.<ref>{{cite journal \| last=James \| first=H.H. \|author2=Coolidge, A S. \| title=The Ground State of the Hydrogen Molecule \| journal=Journal of Chemical Physics \| volume=1 \| issue=12 \| pages=825–835 \| year=1933 \| doi=10.1063/1.1749252 \| bibcode=1933JChPh...1..825J }}</ref>

	== Bond energies and lengths ==		== Bond energies and lengths ==