Niels Bohr’s 1913 quantum model of the atom, which incorporated an explanation of Johannes Rydberg's 1888 formula, Max Planck’s 1900 quantum hypothesis, i.e. that atomic energy radiators have discrete energy values (ε = hν), J.J. Thomson’s 1904 plum pudding model, Albert Einstein’s 1905 light quanta postulate, and Ernest Rutherford's 1907 positive atomic nucleus discovery.

The history of quantum mechanics as this interlaces with history of quantum chemistry began essentially with the 1838 discovery of cathode rays by Michael Faraday, the 1859 statement of the black body radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig Boltzmann that the energy states of a physical system could be discrete, and the 1900 quantum hypothesis by Max Planck that any energy radiating atomic system can theoretically be divided into a number of discrete ‘energy elements’ ε such that each of these energy elements is proportional to the frequency ν with which they each individually radiate energy, as defined by the following formula: Image File history File links Size of this preview: 637 × 600 pixel Image in higher resolution (1943 × 1829 pixel, file size: 241 KB, MIME type: image/jpeg) made by User:Sadi Carnot I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document... Image File history File links Size of this preview: 637 × 600 pixel Image in higher resolution (1943 × 1829 pixel, file size: 241 KB, MIME type: image/jpeg) made by User:Sadi Carnot I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document... Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in 1922. ... Janne Rydberg Johannes Robert Rydberg, commonly known as Janne Rydberg, (November 8, 1854 - December 28, 1919), was a Swedish physicist mainly known for devising the Rydberg formula, in 1888, which is used to predict the wavelengths of photons (of light and other electromagnetic radiation) emitted by changes in the energy... The Rydberg formula (Rydberg-Ritz formula) is used in atomic physics for determining the full spectrum of light emission from hydrogen, later extended to be useful with any element by use of the Rydberg-Ritz combination principle. ... Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947 in Göttingen, Germany) was a German physicist. ... Sir Joseph John Thomson, OM , FRS (December 18, 1756 – August 30, 1940) often known as J. J. Thomson, was an English physicist, the discoverer of the electron. ... A schematic representation of the plum pudding model of the atom. ... “Einstein” redirects here. ... In physics, the photon (from Greek φοτος, meaning light) is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by quantum electrodynamics (QED) which is the oldest part of the Standard Model of particle physics. ... Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 - 19 October 1937), widely referred to as Lord Rutherford, was a nuclear physicist who became known as the father of nuclear physics. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... Fig. ... Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics and quantum field theory to address issues and problems in chemistry. ... Alternative meanings: There is also an Electric-type Pok mon named Electrode. ... Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Gustav Robert Kirchhof (March 12, 1824 – October 17, 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. ... Ludwig Eduard Boltzmann (Vienna, Austrian Empire, February 20, 1844 – Duino near Trieste, September 5, 1906) was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics. ... Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947 in Göttingen, Germany) was a German physicist. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ...

where h is a numerical value called Planck’s constant. Then, in 1905, to explain the photoelectric effect (1839), i.e. that shining light on certain materials can function to eject electrons from the material, Albert Einstein postulated, as based on Planck’s quantum hypothesis, that light itself consists of individual quantum particles, which later came to be called photons (1926). The phrase "quantum mechanics" was first used in Max Born's 1924 paper "Zur Quantenmechanik". In the years to follow, this theoretical basis slowly began to be applied to chemical structure, reactivity, and bonding. A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... “Einstein” redirects here. ... This article does not cite any references or sources. ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Max Born (December 11, 1882 in Breslau – January 5, 1970 in Göttingen) was a mathematician and physicist. ...

Overview

In short, in 1900, German physicist Max Planck introduced the idea that energy is quantized, in order to derive a formula for the observed frequency dependence of the energy emitted by a black body. In 1905, Einstein explained the photoelectric effect by postulating that light, or more specifically all electromagnetic radiation, can be divided into a finite number of "energy quanta" that are localized points in space. From the introduction section of his March 1905 quantum paper, “On a heuristic viewpoint concerning the emission and transformation of light”, Einstein states: Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947 in Göttingen, Germany) was a German physicist. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Einstein redirects here. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ...

This statement has been called the most revolutionary sentence written by a physicist of the twentieth century.^[1] These energy quanta later came to be called "photons", a term introduced by Gilbert N. Lewis in 1926. The idea that each photon had to consist of energy in terms of quanta was a remarkable achievement as it effectively removed the possibility of black body radiation attaining infinite energy if it were to be explained in terms of wave forms only. In 1913, Bohr explained the spectral lines of the hydrogen atom, again by using quantization, in his paper of July 1913 On the Constitution of Atoms and Molecules. In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... Lewis in the Berkeley Lab Gilbert Newton Lewis (October 23, 1875-March 23, 1946) was a famous American physical chemist. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. ...

These theories, though successful, were strictly phenomenological: there was no rigorous justification for quantization (aside, perhaps, for Henri Poincaré's discussion of Planck's theory in his 1912 paper Sur la théorie des quanta). They are collectively known as the old quantum theory. The term phenomenology in modern science, especially in physics, is used to describe a body of knowledge which relates several different empirical observations of phenomena to each other, in a way which is consistent with fundamental theory, but is not directly derived from theory. ... Jules TuPac Henri Poincaré (April 29, 1854 – July 17, 1912) (IPA: [][1]) was one of Frances greatest mathematicians and theoretical physicists, and a philosopher of science. ...

The phrase "quantum physics" was first used in Johnston's Planck's Universe in Light of Modern Physics (1931).

In 1924, the French physicist Louis de Broglie put forward his theory of matter waves by stating that particles can exhibit wave characteristics and vice versa. This theory was for a single particle and derived from special relativity theory. Modern quantum mechanics was born in 1925, when the German physicists Werner Heisenberg and Max Born developed matrix mechanics and the Austrian physicist Erwin Schrödinger invented wave mechanics and the non-relativistic Schrödinger equation as an approximation to the generalised case of de Broglie's theory (see Hanle (1977)). Schrödinger subsequently showed that the two approaches were equivalent. Louis-Victor-Pierre-Raymond, 7th duc de Broglie, generally known as Louis de Broglie (August 15, 1892–March 19, 1987), was a French physicist and Nobel Prize laureate. ... The special theory of relativity was proposed in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. Some three centuries earlier, Galileos principle of relativity had stated that all uniform motion was relative, and that there was no absolute and well-defined state of rest... Werner Karl Heisenberg (December 5, 1901 – February 1, 1976) was a celebrated German physicist and Nobel laureate, one of the founders of quantum mechanics, and acknowledged to be one of the most important physicists of the twentieth century. ... Max Born (December 11, 1882 in Breslau – January 5, 1970 in Göttingen) was a mathematician and physicist. ... Matrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg in 1925. ... Bust of Schrödinger, in the courtyard arcade of the main building, University of Vienna, Austria. ... The wave equation is an important partial differential equation which generally describes all kinds of waves, such as sound waves, light waves and water waves. ...

Heisenberg formulated his uncertainty principle in 1927, and the Copenhagen interpretation took shape at about the same time. Starting around 1927, Paul Dirac began the process of unifying quantum mechanics with special relativity by proposing the Dirac equation for the electron. The Dirac equation achieves the relativistic description of the wavefunction of an electron that Schrödinger failed to obtain. It predicts electron spin and led Dirac to predict the existence of the positron. He also pioneered the use of operator theory, including the influential bra-ket notation, as described in his famous 1930 textbook. During the same period, Hungarian polymath John von Neumann formulated the rigorous mathematical basis for quantum mechanics as the theory of linear operators on Hilbert spaces, as described in his likewise famous 1932 textbook. These, like many other works from the founding period still stand, and remain widely used. In quantum physics, the Heisenberg uncertainty principle is a mathematical property of a pair of canonical conjugate quantities - usually stated in a form of reciprocity of spans of their spectra. ... Paul Adrien Maurice Dirac, OM, FRS (IPA: [dɪræk]) (August 8, 1902 – October 20, 1984) was a British theoretical physicist and a founder of the field of quantum physics. ... The special theory of relativity was proposed in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. Some three centuries earlier, Galileos principle of relativity had stated that all uniform motion was relative, and that there was no absolute and well-defined state of rest... In physics, the Dirac equation is a relativistic quantum mechanical wave equation formulated by British physicist Paul Dirac in 1928 and provides a description of elementary spin-½ particles, such as electrons, consistent with both the principles of quantum mechanics and the theory of special relativity. ... e- redirects here. ... In physics, the Dirac equation is a relativistic quantum mechanical wave equation formulated by British physicist Paul Dirac in 1928 and provides a description of elementary spin-½ particles, such as electrons, consistent with both the principles of quantum mechanics and the theory of special relativity. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... Bra-ket notation is the standard notation for describing quantum states in the theory of quantum mechanics. ... John von Neumann (Hungarian Margittai Neumann János Lajos) (born December 28, 1903 in Budapest, Austria-Hungary; died February 8, 1957 in Washington D.C., United States) was a Hungarian-born American mathematician who made contributions to quantum physics, functional analysis, set theory, topology, economics, computer science, numerical analysis, hydrodynamics...

The field of quantum chemistry was pioneered by physicists Walter Heitler and Fritz London, who published a study of the covalent bond of the hydrogen molecule in 1927. Quantum chemistry was subsequently developed by a large number of workers, including the American theoretical chemist Linus Pauling at Cal Tech, and John Slater into various theories such as Molecular Orbital Theory or Valence Theory. Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics and quantum field theory to address issues and problems in chemistry. ... Walter Heinrich Heitler (02. ... Fritz Wolfgang London (March 7, 1900–March 30, 1954) was a German-born American physicist for whom the London force is named. ... Covalent bonding is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. ... The Hydrogen molecule consists of two Hydrogen atoms, in other words it is a diatomic molecule. ... Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American quantum chemist and biochemist. ...

Beginning in 1927, attempts were made to apply quantum mechanics to fields rather than single particles, resulting in what are known as quantum field theories. Early workers in this area included P.A.M. Dirac, W. Pauli, V. Weisskopf, and P. Jordan. This area of research culminated in the formulation of quantum electrodynamics by R.P. Feynman, F. Dyson, J. Schwinger, and S.I. Tomonaga during the 1940s. Quantum electrodynamics is a quantum theory of electrons, positrons, and the electromagnetic field, and served as a role model for subsequent quantum field theories. The theory of quantum chromodynamics was formulated beginning in the early 1960s. The theory as we know it today was formulated by Politzer, Gross and Wilzcek in 1975. Building on pioneering work by Schwinger, Higgs, Goldstone, Glashow, Weinberg and Salam independently showed how the weak nuclear force and quantum electrodynamics could be merged into a single electroweak force. Quantum field theory (QFT) is the quantum theory of fields. ... Paul Adrien Maurice Dirac, OM, FRS (IPA: [dɪræk]) (August 8, 1902 – October 20, 1984) was a British theoretical physicist and a founder of the field of quantum physics. ... This article is about Austrian-Swiss physicist Wolfgang Pauli. ... External links National Academy of Sciences biography Categories: People stubs | 1908 births | 2002 deaths | Manhattan Project | Physicists ... Pascual Jordan (October 18, 1902 in Hanover - July 31, 1980 in Hamburg) was a German physicist. ... Quantum electrodynamics (QED) is a relativistic quantum field theory of electromagnetism. ... Richard Phillips Feynman (May 11, 1918 – February 15, 1988; IPA: ) was an American physicist known for expanding the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, and particle theory. ... Freeman John Dyson (born December 15, 1923) is a British-born American physicist and mathematician, famous for his work in quantum mechanics, solid-state physics, nuclear weapons design and policy, and for his serious theorizing in futurism and science fiction concepts, including the search for extraterrestrial intelligence. ... Julian Seymour Schwinger (February 12, 1918 -- July 16, 1994) was an American theoretical physicist. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... e- redirects here. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... The electromagnetic field is a physical field that is produced by electrically charged objects and which affects the behaviour of charged objects in the vicinity of the field. ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... Prof. ... David Gross and his wife in Santa Barbara David Jonathan Gross (born February 19, 1941 in Washington, D.C.) is an American physicist and string theorist. ... Frank Wilczek (born May 15, 1951) is a Nobel prize winning American physicist. ... Julian Seymour Schwinger (February 12, 1918 -- July 16, 1994) was an American theoretical physicist. ... Peter Ware Higgs (born May 29, 1929), FRSE, FRS, until recently held a personal chair in theoretical physics at the University of Edinburgh and is now an emeritus professor. ... Jeffrey Goldstone is a theoretical physicist and an emeritus physics faculty at MIT. He was educated at the Cambridge University. ... Sheldon Glashow at Harvard University Professor Sheldon Lee Glashow (born December 5, 1932) is an American physicist. ... Steven Weinberg (born May 3, 1933) is an American physicist. ... Abdus Salam at Nobel Prize ceremony with the King of Sweden Dr. Abdus Salam (Urdu: عبد السلام) (January 29, 1926 at Santokdas, Sahiwal in Punjab – 21 November 1996 in Oxford, England) was a Pakistani theoretical physicist who received the Nobel Prize in Physics in 1979 for his work in electroweak theory which... In physics, the electroweak theory presents a unified description of two of the four fundamental forces of nature: electromagnetism and the weak nuclear force. ...

Timeline

The following timeline shows the key steps and contributors in the precursory development of quantum mechanics and quantum chemistry: Fig. ... Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics and quantum field theory to address issues and problems in chemistry. ...

Luigi Galvani - Italian physician famous for making frogs legs twitch. ... Look up Spark in Wiktionary, the free dictionary. ... Count Alessandro Giuseppe Antonio Anastasio Volta (February 18, 1745 - March 5, 1827) was an Italian physicist known especially for the development of the electric battery in 1800. ... A copper-zinc Voltaic pile A Voltaic pile on display in the Tempio Voltiano The Voltaic pile is the first modern electric battery, invented by Alessandro Volta in 1800. ... Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ... A schematic diagram of a Crookes tube apparatus. ... Diagram of a zinc anode in a galvanic cell. ... Diagram of a copper cathode in a Daniells cell. ... Sir Edward Frankland (January 18, 1825 – August 9, 1899) was an English chemist. ... In chemistry, valency is the power of an atom of an element to combine with other atoms measured by the number of electrons which an atom will give, take, or share to form a chemical compound. ... Gustav Robert Kirchhof (March 12, 1824 – October 17, 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. ... Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... Ludwig Eduard Boltzmann (February 20, 1844 – September 5, 1906) was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics. ... Sir William Crookes, OM, FRS (17 June 1832 – 4 April 1919) was an English chemist and physicist. ... Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ... Alfred Werner (December 12, 1866 - November 15, 1919) was a German Nobel prize-winning chemist. ... Look up affinity in Wiktionary, the free dictionary. ... Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894) was the German physicist and mechanician for whom the hertz, an SI unit, is named. ... Antoine Henri Becquerel (December 15, 1852 – August 25, 1908) was a French physicist, Nobel laureate, and one of the discoverers of radioactivity. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... watecs ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ... An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ... Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. ... This article is about electromagnetic radiation. ... ... It has been suggested that optical field be merged into this article or section. ... Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ... e- redirects here. ... A schematic representation of the plum pudding model of the atom. ... Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947 in Göttingen, Germany) was a German physicist. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ... Lewis in the Berkeley Lab Gilbert Newton Lewis (October 23, 1875-March 23, 1946) was a famous American physical chemist. ... The bonding in carbon dioxide The octet rule is a simple chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, similar to the electronic configuration of a noble gas. ... The cubical atom was an early atomic model developed by Gilbert N. Lewis in 1916 to account for the phenomenon of valency. ... Covalent bonding is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. ... Richard Wilhelm Heinrich Abegg (1869 – 1910) was a German chemist and pioneer of valence theory. ... In chemistry, Abegg’s rule states that the difference between the maximum positive and negative valence of an element is frequently eight. ... “Einstein” redirects here. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... This article does not cite any references or sources. ... Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 - 19 October 1937), widely referred to as Lord Rutherford, was a nuclear physicist who became known as the father of nuclear physics. ... An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in 1922. ... The Rydberg formula (Rydberg-Ritz formula) is used in atomic physics for determining the full spectrum of light emission from hydrogen, later extended to be useful with any element by use of the Rydberg-Ritz combination principle. ... Arnold Johannes Wilhelm Sommerfeld (December 5, 1868 in Königsberg, East Prussia – April 26, 1951 in Munich, Germany) was a German physicist who introduced the fine-structure constant in 1919. ... The Zeeman effect (IPA ) is the splitting of a spectral line into several components in the presence of a magnetic field. ... Irving Langmuir at home (c. ... A coordinate covalent bond (also known as dative bond) is a description of covalent bonding in many kinds of compounds. ... Louis-Victor-Pierre-Raymond, 7th duc de Broglie, generally known as Louis de Broglie (August 15, 1892 – March 19, 1987), was a French physicist and Nobel Prize laureate. ... A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ... In classical mechanics, momentum (pl. ... e- redirects here. ... Carl von Weizacker & Friedrich Hund, Goettingen DPI Friedrich Hund (February 4, 1896 - March 31, 1997) : German physicist known for his work on atoms and molecules. ... Hunds rule of maximum multiplicity, often simply referred to as Hunds rule, is a principle of atomic chemistry which states that a greater total spin state usually makes the resulting atom more stable, most commonly manifested in a lower energy state, because it forces the unpaired electrons to... In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... In chemistry, valence electrons are the electrons contained in the outermost, or valence, electron shell of an atom. ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... This article is about Austrian-Swiss physicist Wolfgang Pauli. ... The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... Bust of Schrödinger, in the courtyard arcade of the main building, University of Vienna, Austria. ... For a non-technical introduction to the topic, please see Introduction to quantum mechanics. ... In chemistry, valence bond theory explains the nature of a chemical bond in a molecule in terms of atomic valencies. ... Walter Heinrich Heitler (02. ... This article discusses the concept of a wavefunction as it relates to quantum mechanics. ... Covalent bonding is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. ... Robert Sanderson Mulliken (June 7, 1896-October 31, 1986) was an American physicist and chemist, primarily responsible for the elaboration of the molecular orbital method of computing the structure of molecules. ... Electron atomic and molecular orbitals, showing among others the sigma bond of two s-orbitals and a sigma bond of two p-orbitals In chemistry, sigma bonds (σ bonds) are a type of covalent chemical bond. ... Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (Ï€ bonds) are chemical bonds of the covalent type, where two lobes of one involved electron orbital overlap two lobes of the other involved electron orbital. ... In chemistry, delta bonds (δ bonds) are chemical bonds of the covalent type, where four lobes of one involved electron orbital overlap four lobes of the other involved electron orbital. ... Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American quantum chemist and biochemist. ... A chemical bond is the physical process responsible for the attractive interactions between atoms and molecules, and that which confers stability to diatomic and polyatomic chemical compounds. ... Fig. ... This article is about resonance in physics. ... John Edward Lennard-Jones (October 27, 1894 - November 1, 1954) was a mathematician who held a chair of theoretical physics at Bristol University, and then a chair of theoretical science at Cambridge University. ... The linear combination of atomic orbitals molecular orbital method (usually called the LCAO MO method) is a technique for calculating molecular orbitals in quantum chemistry. ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... Werner Karl Heisenberg (December 5, 1901 – February 1, 1976) was a celebrated German physicist and Nobel laureate, one of the founders of quantum mechanics, and acknowledged to be one of the most important physicists of the twentieth century. ... Perturbation theory comprises mathematical methods that are used to find an approximate solution to a problem which cannot be solved exactly, by starting from the exact solution of a related problem. ... Resonance in chemistry is a tool used to represent and model certain types of non-classical molecular structures. ... In theoretical physics, exchange forces are physical constraints whose effect resembles actual forces. ... Charles Alfred Coulson (1910-1974) was a prominent researcher in the field of theoretical chemistry. ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... This article discusses the concept of a wavefunction as it relates to quantum mechanics. ... The Hydrogen molecule consists of two Hydrogen atoms, in other words it is a diatomic molecule. ... Clemens C.J. Roothaan was born in 1918 in Nijmegen, the Netherlands. ... George Garfield Hall (born March 5, 1925), is an applied mathematician and scientist of distinction, known for original work and contributions to the field of Quantum chemistry. ... The Roothaan equations are a representation of the Hartree-Fock equation in a non orthonormal basis set which can be of Gaussian-type or Slater-type. ...

Founding experiments

• Thomas Young's double-slit experiment demonstrating the wave nature of light (c1805)
• Henri Becquerel discovers radioactivity (1896)
• Joseph John Thomson's cathode ray tube experiments (discovers the electron and its negative charge) (1897)
• The study of black body radiation between 1850 and 1900, which could not be explained without quantum concepts.
• The photoelectric effect: Einstein explained this in 1905 (and later received a Nobel prize for it) using the concept of photons, particles of light with quantized energy
• Robert Millikan's oil-drop experiment, which showed that electric charge occurs as quanta (whole units), (1909)
• Ernest Rutherford's gold foil experiment disproved the plum pudding model of the atom which suggested that the mass and positive charge of the atom are almost uniformly distributed. (1911)
• Otto Stern and Walther Gerlach conduct the Stern-Gerlach experiment, which demonstrates the quantized nature of particle spin (1920)
• Clinton Davisson and Lester Germer demonstrate the wave nature of the electron^[2] in the Electron diffraction experiment (1927)
• Clyde L. Cowan and Frederick Reines confirm the existence of the neutrino in the neutrino experiment (1955)
• Claus Jönsson`s double-slit experiment with electrons (1961)
• The Quantum Hall effect, discovered in 1980 by Klaus von Klitzing. The quantized version of the Hall effect has allowed for the definition of a new practical standard for electrical resistance and for an extremely precise independent determination of the fine structure constant.

Thomas Young, English scientist Thomas Young (June 13, 1773-May 10, 1829) was a English polymath, contributing to optics, physiology, and Egyptology, among other fields. ... Double-slit diffraction and interference pattern The double-slit experiment consists of letting light diffract through two slits, which produces fringes or wave-like interference patterns on a screen. ... Antoine Henri Becquerel (December 15, 1852 – August 25, 1908) was a French physicist, Nobel laureate, and one of the discoverers of radioactivity. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... Sir Joseph John Thomson Sir Joseph John Thomson (18 December 1856 – 30 August 1940), often known as J. J. Thomson, was an English physicist, the discoverer of the electron. ... e- redirects here. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... “Einstein” redirects here. ... Robert Andrews Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist who won the 1923 Nobel Prize for his measurement of the charge on the electron and for his work on the photoelectric effect. ... The purpose of Robert Millikans oil-drop experiment (1909) was to measure the electric charge of the electron. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... In physics, a quantum (plural: quanta) is an indivisible entity of energy. ... Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 - 19 October 1937), widely referred to as Lord Rutherford, was a nuclear physicist who became known as the father of nuclear physics. ... Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. ... Properties In chemistry and physics, an atom (Greek ἄτομος or átomos meaning indivisible) is the smallest particle still characterizing a chemical element. ... Otto Stern Otto Stern (February 17, 1888 – August 17, 1969) was an German physicist and Nobel laureate. ... Walther Gerlach (1 August 1889 - 10 August 1979) was a German physicist. ... In quantum mechanics, the Stern–Gerlach experiment, named after Otto Stern and Walther Gerlach, is a celebrated experiment in 1920 on deflection of particles, often used to illustrate basic principles of quantum mechanics. ... In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ... Clinton Joseph Davisson (22 October 1881–1 February 1958), was an American physicist. ... Lester Germer (full name Lester Halbert Germer; 1896–1971), American physicist. ... e- redirects here. ... This article is in need of attention from an expert on the subject. ... Clyde Lorrain Cowan Jr (1919–1974) was a captain in the United States Army Air Force. ... Frederick Reines Frederick Reines (March 16, 1918 - August 26, 1998) was an American physicist. ... Neutrinos are elementary particles denoted by the symbol ν. Travelling close to the speed of light, lacking electric charge and able to pass through ordinary matter almost undisturbed, they are extremely difficult to detect. ... The neutrino experiment, also called the Cowan and Reines neutrino experiment, was performed by Clyde L. Cowan and Frederick Reines in 1956. ... Double-slit diffraction and interference pattern The double-slit experiment consists of letting light diffract through two slits, which produces fringes or wave-like interference patterns on a screen. ... The quantum Hall effect is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall conductance takes on the quantized values where is the elementary charge and is Plancks constant. ... Klaus von Klitzing, (born June 28, 1943 in German occupied Åšroda Wielkopolska) is a German physicist. ... Hall effect diagram, showing electron flow (rather than conventional current). ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ... The fine-structure constant or Sommerfeld fine-structure constant, usually denoted , is the fundamental physical constant characterizing the strength of the electromagnetic interaction. ...

References

• Hanle, P.A. (1977) Erwin Schrodinger's Reaction to Louis de Broglie's Thesis on the Quantum Theory. Isis, Vol. 68, No. 4 (Dec., 1977), pp. 606-609

See also

• Quantum
• History of the molecule
• History of thermodynamics
• History of chemistry

In physics, a quantum (plural: quanta) is an indivisible entity of energy. ... In chemistry, the history of the molecule traces the origins of the concept or idea of the existence, in nature, of a bonded structure of two or more atoms, according to which the structures of the universe are built. ... Savery Engine [1698] The history of thermodynamics is a core strand in the history of physics and an important one in the history of science. ... Portrait of Monsieur Lavoisier and his Wife, by Jacques-Louis David The history of chemistry may be said to begin with the distinction of chemistry from alchemy by Robert Boyle in his work The Sceptical Chymist (1661). ...

External links

• A History of Quantum Mechanics
• A Brief History of Quantum Mechanics
• Homepage of the Quantum History Project