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23,500 | In some general chemistry textbooks, hybridization is presented for main group coordination number 5 and above using an "expanded octet" scheme with d-orbitals first proposed by Pauling. However, such a scheme is now considered to be incorrect in light of computational chemistry calculations. In 1990, Eric Alfred Magnu... | Sp hybridization | 0.808767 |
23,501 | Infrared cirrus or galactic cirrus are galactic filamentary structures seen in space over most of the sky that emit far-infrared light. The name is given because the structures are cloud-like in appearance. These structures were first detected by the Infrared Astronomy Satellite at wavelengths of 60 and 100 micrometres... | Infrared cirrus | 0.808767 |
23,502 | The Transporter Classification Database (or TCDB) is an International Union of Biochemistry and Molecular Biology (IUBMB)-approved classification system for membrane transport proteins, including ion channels. | Transporter Classification Database | 0.808764 |
23,503 | The Journal of Atmospheric and Solar-Terrestrial Physics is a monthly peer-reviewed scientific journal covering the atmospheric and solar-terrestrial physics. It was established in 1950 as the Journal of Atmospheric and Terrestrial Physics, obtaining its current name in 1997. It is published by Elsevier and sponsored b... | Journal of Atmospheric and Solar-Terrestrial Physics | 0.808764 |
23,504 | A TI-polaron (translation-invariant polaron) is a type of elementary quasiparticle in solid-state physics. The ground state of TI-polaron is a delocalized state of electron-phonon system: the probabilities of electron's occurrence at any point of a space are similar. Both the electron density and the amplitudes of phon... | TI-polaron | 0.80876 |
23,505 | Clifford algebras are thus non-anticommutative ("quantum") deformations of the exterior algebra. They are studied in geometric algebra. Another alternative is to consider vector fields as derivations. The (noncommutative) algebra of differential operators they generate is the Weyl algebra and is a noncommutative ("quan... | Exterior calculus | 0.808759 |
23,506 | On a pseudo-Riemannian manifold, 1-forms can be identified with vector fields; vector fields have additional distinct algebraic structures, which are listed here for context and to avoid confusion. Firstly, each (co)tangent space generates a Clifford algebra, where the product of a (co)vector with itself is given by th... | Exterior calculus | 0.808759 |
23,507 | The algebra of differential forms along with the exterior derivative defined on it is preserved by the pullback under smooth functions between two manifolds. This feature allows geometrically invariant information to be moved from one space to another via the pullback, provided that the information is expressed in term... | Exterior calculus | 0.808759 |
23,508 | {\displaystyle df(x)=f'(x)dx.} ) This allows expressing the fundamental theorem of calculus, the divergence theorem, Green's theorem, and Stokes' theorem as special cases of a single general result, the generalized Stokes theorem. Differential 1-forms are naturally dual to vector fields on a differentiable manifold, an... | Exterior calculus | 0.808759 |
23,509 | {\displaystyle dx,dy,\ldots .} On an n-dimensional manifold, the top-dimensional form (n-form) is called a volume form. The differential forms form an alternating algebra. | Exterior calculus | 0.808759 |
23,510 | In mathematics, differential forms provide a unified approach to define integrands over curves, surfaces, solids, and higher-dimensional manifolds. The modern notion of differential forms was pioneered by Élie Cartan. It has many applications, especially in geometry, topology and physics. For instance, the expression f... | Exterior calculus | 0.808759 |
23,511 | In organic chemistry, methylenation is a chemical reaction that inserts a methylene (−CH2−) group into a chemical compound: A − B + CH 2 ⟶ A − CH 2 − B {\displaystyle {\ce {A-B}}+{\color {red}{\ce {CH2}}}\longrightarrow {\ce {A}}{\color {red}{\ce {-CH2 -}}}{\ce {B}}} Typically, the reaction is used to prepare terminal ... | Methylenation | 0.808758 |
23,512 | Other characters with similar appearance but different meanings include: U+00BA º MASCULINE ORDINAL INDICATOR (º) (indicator used in Italian, Spanish and Portuguese that follows a numeral denoting that it is an ordinal number, rather than a cardinal number; varies with the font and sometimes underlined) U+1D52 ᵒ MODIFI... | Degree sign | 0.808757 |
23,513 | In statistics, bivariate data is data on each of two variables, where each value of one of the variables is paired with a value of the other variable. It is a specific but very common case of multivariate data. The association can be studied via a tabular or graphical display, or via sample statistics which might be us... | Bivariate data | 0.808752 |
23,514 | In the analysis of bivariate data, one typically either compares summary statistics of each of the variables or uses regression analysis to find the strength and direction of a specific relationship between the variables. If each variable can only take one of a small number of values, such as only "male" or "female", o... | Bivariate data | 0.808752 |
23,515 | For discrete calculation without calculus, marginal cost equals the change in total (or variable) cost that comes with each additional unit produced. Since fixed cost does not change in the short run, it has no effect on marginal cost. For instance, suppose the total cost of making 1 shoe is $30 and the total cost of m... | Marginal costs | 0.808751 |
23,516 | Or another way of putting it: a nanometer is the amount an average man's beard grows in the time it takes him to raise the razor to his face.Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from molecular components which assemble themselves chemically by prin... | Nanotechnology | 0.808746 |
23,517 | The lower limit is set by the size of atoms (hydrogen has the smallest atoms, which are approximately a quarter of a nm kinetic diameter) since nanotechnology must build its devices from atoms and molecules. The upper limit is more or less arbitrary but is around the size below which the phenomena not observed in large... | Nanotechnology | 0.808746 |
23,518 | By comparison, typical carbon-carbon bond lengths, or the spacing between these atoms in a molecule, are in the range 0.12–0.15 nm, and a DNA double-helix has a diameter around 2 nm. On the other hand, the smallest cellular life-forms, the bacteria of the genus Mycoplasma, are around 200 nm in length. By convention, na... | Nanotechnology | 0.808746 |
23,519 | Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced. In its original sense, nanotechnology refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complet... | Nanotechnology | 0.808746 |
23,520 | In vector calculus, a complex lamellar vector field is a vector field which is orthogonal to a family of surfaces. In the broader context of differential geometry, complex lamellar vector fields are more often called hypersurface-orthogonal vector fields. They can be characterized in a number of different ways, many of... | Lamellar vector field | 0.808746 |
23,521 | Using a different formulation of the Frobenius theorem, it is also equivalent to require that ω is locally expressible as λ du for some functions λ and u.In the special case of vector fields on three-dimensional Euclidean space, the hypersurface-orthogonal condition is equivalent to the complex lamellar condition, as s... | Lamellar vector field | 0.808746 |
23,522 | In greater generality, a vector field F on a pseudo-Riemannian manifold is said to be hypersurface-orthogonal if through an arbitrary point there is a smoothly embedded hypersurface which, at all of its points, is orthogonal to the vector field. By the Frobenius theorem this is equivalent to requiring that the Lie brac... | Lamellar vector field | 0.808746 |
23,523 | Synthetic virology is a branch of virology engaged in the study and engineering of synthetic man-made viruses. It is a multidisciplinary research field at the intersection of virology, synthetic biology, computational biology, and DNA nanotechnology, from which it borrows and integrates its concepts and methodologies. ... | Synthetic virology | 0.808745 |
23,524 | The ePSORTdb data is derived from a manual literature search (using PubMed) as well as Swiss-Prot annotations. The cPSORTdb predictions are generated using the updated PSORTb 3.0 tool.PSORTdb can be accessed through a web interface or via BLAST. The entire database is also available for download under the GNU General P... | PSORTdb | 0.808743 |
23,525 | PSORTdb is a database of protein subcellular localization (SCL) for bacteria and archaea. It is a member of the PSORT family of bioinformatics tools. The database consists of two datasets, ePSORTdb and cPSORTdb, which contain information determined through experimental validation and computational prediction, respectiv... | PSORTdb | 0.808743 |
23,526 | Pretty-printing usually refers to displaying mathematical expressions similar to the way they would be typeset professionally. For example, in computer algebra systems such as Maxima or Mathematica the system may write output like "x ^ 2 + 3 * x" as " x 2 + 3 x {\displaystyle x^{2}+3x} ". Some graphing calculators, suc... | Code beautification | 0.808741 |
23,527 | Here is a list of algebraic properties satisfied by the set of constraints. Both operations are associative and commutative, Sum is distributive over intersection, that is, for any three constraints, ( ( ≺ 1 , m 1 ) ⊓ ( ≺ 2 , m 2 ) ) + ( ≺ 3 , m 3 ) {\displaystyle ((\prec _{1},m_{1})\sqcap (\prec _{2},m_{2}))+(\prec _{... | Difference bound matrix | 0.808741 |
23,528 | In order to define the data structure difference bound matrix, it is first required to give a data structure to encode atomic constraints. Furthermore, we introduce an algebra for atomic constraints. This algebra is similar to the tropical semiring, with two modifications: An arbitrary ordered monoid may be used instea... | Difference bound matrix | 0.808741 |
23,529 | Müllerian mimicry, too, in which two or more distasteful species that share one or more predators have come to mimic each other's warning signals, was clearly adaptive; Fritz Müller described the effect in 1879, in an account notable for being the first use of a mathematical argument in evolutionary ecology to show how... | Coloration evidence for natural selection | 0.80874 |
23,530 | The object of Warning Colours is to assist the education of enemies, enabling them to easily learn and remember the animals which are to be avoided. The great advantage conferred upon the conspicuous species is obvious when it is remembered that such an easy and successful education means an education involving only a ... | Coloration evidence for natural selection | 0.80874 |
23,531 | In the words of camouflage researchers Innes Cuthill and A. Székely, the English zoologist and camouflage expert Hugh Cott's 1940 book Adaptive Coloration in Animals provided "persuasive arguments for the survival value of coloration, and for adaptation in general, at a time when natural selection was far from universa... | Coloration evidence for natural selection | 0.80874 |
23,532 | Vladimir Markovnikov, born in 1838, was a Russian scientist who did most of his work at Kazan University in Russia. At Kazan, he studied under Butlerov in a laboratory better known as "the cradle of Russian organic chemistry", after which he also studied chemistry in Germany for two years. Markovnikov's contributions t... | History of chemistry | 0.808739 |
23,533 | There were several problems with alchemy, as seen from today's standpoint. There was no systematic naming scheme for new compounds, and the language was esoteric and vague to the point that the terminologies meant different things to different people. In fact, according to The Fontana History of Chemistry (Brock, 1992)... | History of chemistry | 0.808739 |
23,534 | Sir William Ramsay worked with Frederick Soddy to demonstrate, in 1903, that alpha particles (helium nuclei) were continually produced during the radioactive decay of a sample of radium. Ramsay was awarded the 1904 Nobel Prize for Chemistry in recognition of "services in the discovery of the inert gaseous elements in t... | History of chemistry | 0.808739 |
23,535 | The most celebrated discoveries of Scottish chemist William Ramsay were made in inorganic chemistry. Ramsay was intrigued by the British physicist John Strutt, 3rd Baron Rayleigh's 1892 discovery that the atomic weight of nitrogen found in chemical compounds was lower than that of nitrogen found in the atmosphere. He a... | History of chemistry | 0.808739 |
23,536 | The later part of the nineteenth century saw a huge increase in the exploitation of petroleum extracted from the earth for the production of a host of chemicals and largely replaced the use of whale oil, coal tar and naval stores used previously. Large-scale production and refinement of petroleum provided feedstocks fo... | History of chemistry | 0.808739 |
23,537 | The history of chemistry represents a time span from ancient history to the present. By 1000 BC, civilizations used technologies that would eventually form the basis of the various branches of chemistry. Examples include the discovery of fire, extracting metals from ores, making pottery and glazes, fermenting beer and ... | History of chemistry | 0.808739 |
23,538 | In 1991, Sumio Iijima used electron microscopy to discover a type of cylindrical fullerene known as a carbon nanotube, though earlier work had been done in the field as early as 1951. This material is an important component in the field of nanotechnology. In 1994, K. C. Nicolaou with his group and Robert A. Holton and ... | History of chemistry | 0.808739 |
23,539 | In 1970, John Pople developed the Gaussian program greatly easing computational chemistry calculations. In 1971, Yves Chauvin offered an explanation of the reaction mechanism of olefin metathesis reactions. In 1975, Karl Barry Sharpless and his group discovered stereoselective oxidation reactions including Sharpless ep... | History of chemistry | 0.808739 |
23,540 | For that discovery, he was awarded the Nobel Prize for Physics for 1932. In 1927 he published his uncertainty principle, upon which he built his philosophy and for which he is best known. | History of chemistry | 0.808739 |
23,541 | (This aspect of the quantum theory made Schrödinger and several other physicists profoundly unhappy, and he devoted much of his later life to formulating philosophical objections to the generally accepted interpretation of the theory that he had done so much to create.) German theoretical physicist Werner Heisenberg wa... | History of chemistry | 0.808739 |
23,542 | Adopting a proposal made by Louis de Broglie in 1924 that particles of matter have a dual nature and in some situations act like waves, Schrödinger introduced a theory describing the behaviour of such a system by a wave equation that is now known as the Schrödinger equation. The solutions to Schrödinger's equation, unl... | History of chemistry | 0.808739 |
23,543 | In addition to his original work, he wrote masterful syntheses of several areas of physical theory that are considered classics of scientific literature. In 1926 at the age of 39, Austrian theoretical physicist Erwin Schrödinger produced the papers that gave the foundations of quantum wave mechanics. In those papers he... | History of chemistry | 0.808739 |
23,544 | Einstein stressed the importance of Broglie's work both explicitly and by building further on it. In 1925, Austrian-born physicist Wolfgang Pauli developed the Pauli exclusion principle, which states that no two electrons around a single nucleus in an atom can occupy the same quantum state simultaneously, as described ... | History of chemistry | 0.808739 |
23,545 | This formed the basis of his liquid drop model and later provided a theory base for nuclear fission after its discovery by chemists Otto Hahn and Fritz Strassman, and explanation and naming by physicists Lise Meitner and Otto Frisch. In 1913, Henry Moseley, working from Van den Broek's earlier idea, introduced the conc... | History of chemistry | 0.808739 |
23,546 | Bohr also postulated that electromagnetic radiation is absorbed or emitted when an electron moves from one orbit to another. Because only certain electron orbits are permitted, the emission of light accompanying a jump of an electron from an excited energy state to ground state produces a unique emission spectrum for e... | History of chemistry | 0.808739 |
23,547 | In 1913, Niels Bohr, a Danish physicist, introduced the concepts of quantum mechanics to atomic structure by proposing what is now known as the Bohr model of the atom, where electrons exist only in strictly defined circular orbits around the nucleus similar to rungs on a ladder. The Bohr Model is a planetary model in w... | History of chemistry | 0.808739 |
23,548 | In 1923 Millikan was awarded the Nobel Prize for Physics. In 1909, S. P. L. Sørensen invented the pH concept and developed methods for measuring acidity. In 1911, Antonius Van den Broek proposed the idea that the elements on the periodic table are more properly organized by positive nuclear charge rather than atomic we... | History of chemistry | 0.808739 |
23,549 | In 1903, Mikhail Tsvet invented chromatography, an important analytic technique. In 1904, Hantaro Nagaoka proposed an early nuclear model of the atom, where electrons orbit a dense massive nucleus. In 1905, Fritz Haber and Carl Bosch developed the Haber process for making ammonia, a milestone in industrial chemistry wi... | History of chemistry | 0.808739 |
23,550 | Kekulé is also famous for having clarified the nature of aromatic compounds, which are compounds based on the benzene molecule. In 1865, Adolf von Baeyer began work on indigo dye, a milestone in modern industrial organic chemistry which revolutionized the dye industry. Swedish chemist and inventor Alfred Nobel found th... | History of chemistry | 0.808739 |
23,551 | British chemist and physicist William Crookes is noted for his cathode ray studies, fundamental in the development of atomic physics. His researches on electrical discharges through a rarefied gas led him to observe the dark space around the cathode, now called the Crookes dark space. He demonstrated that cathode rays ... | History of chemistry | 0.808739 |
23,552 | German chemist August Kekulé von Stradonitz's most important single contribution was his structural theory of organic composition, outlined in two articles published in 1857 and 1858 and treated in great detail in the pages of his extraordinarily popular Lehrbuch der organischen Chemie ("Textbook of Organic Chemistry")... | History of chemistry | 0.808739 |
23,553 | The discovery of the artificial synthesis of urea contributed greatly to the theory of isomerism, as the empirical chemical formulas for urea and ammonium cyanate are identical (see Wöhler synthesis). In 1832, Friedrich Wöhler and Justus von Liebig discovered and explained functional groups and radicals in relation to ... | History of chemistry | 0.808739 |
23,554 | The vitalism question was revolutionized in 1828 when Friedrich Wöhler synthesized urea, thereby establishing that organic compounds could be produced from inorganic starting materials and disproving the theory of vitalism. This opened a new research field in chemistry, and by the end of the 19th century, scientists we... | History of chemistry | 0.808739 |
23,555 | A major example was the ion theory of Svante Arrhenius which anticipated ideas about atomic substructure that did not fully develop until the 20th century. Michael Faraday was another early worker, whose major contribution to chemistry was electrochemistry, in which (among other things) a certain quantity of electricit... | History of chemistry | 0.808739 |
23,556 | For 32 years, du Pont served as president of E. I. du Pont de Nemours and Company, which eventually grew into one of the largest and most successful companies in America. Throughout the 19th century, chemistry was divided between those who followed the atomic theory of John Dalton and those who did not, such as Wilhelm... | History of chemistry | 0.808739 |
23,557 | The year 1885 also saw the publishing of J. H. van 't Hoff's L'Équilibre chimique dans les Systèmes gazeux ou dissous à I'État dilué (Chemical equilibria in gaseous systems or strongly diluted solutions), which dealt with this theory of dilute solutions. Here he demonstrated that the "osmotic pressure" in solutions whi... | History of chemistry | 0.808739 |
23,558 | Many reasons for this neglect have been cited, including some theoretical problems, such as Jöns Jacob Berzelius's "dualism", which asserted that compounds are held together by the attraction of positive and negative electrical charges, making it inconceivable that a molecule composed of two electrically similar atoms—... | History of chemistry | 0.808739 |
23,559 | PCR could be used to synthesize specific pieces of DNA and made possible the sequencing of DNA of organisms, which culminated in the huge human genome project. An important piece in the double helix puzzle was solved by one of Pauling's students Matthew Meselson and Frank Stahl, the result of their collaboration (Mesel... | History of chemistry | 0.808739 |
23,560 | By the mid 20th century, in principle, the integration of physics and chemistry was extensive, with chemical properties explained as the result of the electronic structure of the atom; Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more com... | History of chemistry | 0.808739 |
23,561 | Though they developed a consistent quantitative foundation based on notions of atomic and molecular weights, combining proportions, and thermodynamic quantities, chemists had less use of advanced mathematics. Some even expressed reluctance about the use of mathematics within chemistry. For example, the philosopher Augu... | History of chemistry | 0.808739 |
23,562 | Before the 20th century, chemistry was defined as the science of the nature of matter and its transformations. It was therefore distinct from physics which was not concerned with such dramatic transformation of matter. Moreover, in contrast to physics, chemistry remained predominantly a descriptive and empirical scienc... | History of chemistry | 0.808739 |
23,563 | As understanding of the nature of matter has evolved, so too has the self-understanding of the science of chemistry by its practitioners. This continuing historical process of evaluation includes the categories, terms, aims and scope of chemistry. Additionally, the development of the social institutions and networks wh... | History of chemistry | 0.808739 |
23,564 | He also discovered that the "inflammable air" discovered by Cavendish – which he termed hydrogen (Greek for water-former) – combined with oxygen to produce a dew, as Priestley had reported, which appeared to be water. In Reflexions sur le Phlogistique (1783), Lavoisier showed the phlogiston theory of combustion to be i... | History of chemistry | 0.808739 |
23,565 | Anglo-Irish chemist Robert Boyle (1627–1691) is considered to have initiated the gradual separation of chemistry from alchemy. Although skeptical of elements and convinced of alchemy, Boyle played a key part in elevating the "sacred art" as an independent, fundamental and philosophical discipline. He is best known for ... | History of chemistry | 0.808739 |
23,566 | van 't Hoff's publication, called Voorstel tot Uitbreiding der Tegenwoordige in de Scheikunde gebruikte Structuurformules in de Ruimte, etc. (Proposal for the development of 3-dimensional chemical structural formulae) and consisting of twelve pages of text and one page of diagrams, gave the impetus to the development o... | History of chemistry | 0.808739 |
23,567 | An important breakthrough in making sense of the list of known chemical elements (as well as in understanding the internal structure of atoms) was Dmitri Mendeleev's development of the first modern periodic table, or the periodic classification of the elements. Mendeleev, a Russian chemist, felt that there was some typ... | History of chemistry | 0.808739 |
23,568 | Since virtually all chemical processes and many physical ones involve such changes, his work has significantly impacted both the theoretical and experiential aspects of these sciences. In 1877, Ludwig Boltzmann established statistical derivations of many important physical and chemical concepts, including entropy, and ... | History of chemistry | 0.808739 |
23,569 | American mathematical physicist J. Willard Gibbs's work on the applications of thermodynamics was instrumental in transforming physical chemistry into a rigorous deductive science. During the years from 1876 to 1878, Gibbs worked on the principles of thermodynamics, applying them to the complex processes involved in ch... | History of chemistry | 0.808739 |
23,570 | The term chymistry has been used to describe the blend of alchemy and chemistry that existed before that time.During the Renaissance, exoteric alchemy remained popular in the form of Paracelsian iatrochemistry, while spiritual alchemy flourished, realigned to its Platonic, Hermetic, and Gnostic roots. Consequently, the... | History of chemistry | 0.808739 |
23,571 | Alchemy is defined by the Hermetic quest for the philosopher's stone, the study of which is steeped in symbolic mysticism, and differs greatly from modern science. Alchemists toiled to make transformations on an esoteric (spiritual) and/or exoteric (practical) level. It was the protoscientific, exoteric aspects of alch... | History of chemistry | 0.808739 |
23,572 | Glenn T. Seaborg was an American nuclear chemist best known for his work on isolating and identifying transuranium elements (those heavier than uranium). He shared the 1951 Nobel Prize for Chemistry with Edwin Mattison McMillan for their independent discoveries of transuranium elements. Seaborgium was named in his hono... | History of chemistry | 0.808739 |
23,573 | In 1951, a milestone article in quantum chemistry is the seminal paper of Clemens C. J. Roothaan on Roothaan equations. It opened the avenue to the solution of the self-consistent field equations for small molecules like hydrogen or nitrogen. Those computations were performed with the help of tables of integrals which ... | History of chemistry | 0.808739 |
23,574 | The situation around 1930 is described by Paul Dirac: The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be solu... | History of chemistry | 0.808739 |
23,575 | Some view the birth of quantum chemistry in the discovery of the Schrödinger equation and its application to the hydrogen atom in 1926. However, the 1927 article of Walter Heitler and Fritz London is often recognised as the first milestone in the history of quantum chemistry. This is the first application of quantum me... | History of chemistry | 0.808739 |
23,576 | The book contains the results of numerous experiments and establishes an early version of the law of conservation of mass. Working during the time just after Paracelsus and iatrochemistry, Jan Baptist van Helmont suggested that there are insubstantial substances other than air and coined a name for them – "gas", from t... | History of chemistry | 0.808739 |
23,577 | In 1615 Jean Beguin published the Tyrocinium Chymicum, an early chemistry textbook, and in it draws the first-ever chemical equation. In 1637 René Descartes publishes Discours de la méthode, which contains an outline of the scientific method. The Dutch chemist Jan Baptist van Helmont's work Ortus medicinae was publishe... | History of chemistry | 0.808739 |
23,578 | In 1938, Hahn, Meitner and Strassmann discovered nuclear fission. In their second publication on nuclear fission in February of 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chain reaction. Hahn received the 19... | History of chemistry | 0.808739 |
23,579 | Otto Hahn was a German chemist and a pioneer in the fields of radioactivity and radiochemistry. He played a leading role in the discovery of nuclear fission and established nuclear chemistry as a scientic field. Hahn, Lise Meitner and Fritz Strassmann discovered radioactive isotopes of radium, thorium, protactinium and... | History of chemistry | 0.808739 |
23,580 | From his results, Rutherford developed a model of the atom that was similar to the solar system, known as the Rutherford model. Like planets, electrons orbited a central, sun-like nucleus. For his work with radiation and the atomic nucleus, Rutherford received the 1908 Nobel Prize in Chemistry. | History of chemistry | 0.808739 |
23,581 | New Zealand-born chemist and physicist Ernest Rutherford is considered to be "the father of nuclear physics." Rutherford is best known for devising the names alpha, beta, and gamma to classify various forms of radioactive "rays" which were poorly understood at his time (alpha and beta rays are particle beams, while gam... | History of chemistry | 0.808739 |
23,582 | He was elected to the Academy of Sciences (1905), having in 1903 jointly with Marie received the Royal Society's prestigious Davy Medal and jointly with her and Becquerel the Nobel Prize for Physics. He was run over by a carriage in the rue Dauphine in Paris in 1906 and died instantly. His complete works were published... | History of chemistry | 0.808739 |
23,583 | She was the sole winner of the 1911 Nobel Prize for Chemistry. She was the first woman to win a Nobel Prize, and she is the only woman to win the award in two different fields. While working with Marie to extract pure substances from ores, an undertaking that really required industrial resources but that they achieved ... | History of chemistry | 0.808739 |
23,584 | While it took three years for them to isolate radium, they were never able to isolate polonium. Along with the discovery of two new elements and finding techniques for isolating radioactive isotopes, Curie oversaw the world's first studies into the treatment of neoplasms, using radioactive isotopes. With Henri Becquere... | History of chemistry | 0.808739 |
23,585 | This revolutionary idea created the field of atomic physics and the Curies coined the word radioactivity to describe the phenomena. Pierre and Marie further explored radioactivity by working to separate the substances in uranium ores and then using the electrometer to make radiation measurements to 'trace' the minute a... | History of chemistry | 0.808739 |
23,586 | Thus, Volta is considered to be the founder of the discipline of electrochemistry. A Galvanic cell (or voltaic cell) is an electrochemical cell that derives electrical energy from a spontaneous redox reaction taking place within the cell. It generally consists of two different metals connected by a salt bridge, or indi... | History of chemistry | 0.808739 |
23,587 | The real breakthrough came with an international chemical congress held in the German town of Karlsruhe in September 1860, at which most of the leading European chemists were present. The Karlsruhe Congress had been arranged by Kekulé, Wurtz, and a few others who shared Cannizzaro's sense of the direction chemistry sho... | History of chemistry | 0.808738 |
23,588 | In 1840, Germain Hess proposed Hess's law, an early statement of the law of conservation of energy, which establishes that energy changes in a chemical process depend only on the states of the starting and product materials and not on the specific pathway taken between the two states. In 1847, Hermann Kolbe obtained ac... | History of chemistry | 0.808738 |
23,589 | In 1754, Scottish chemist Joseph Black isolated carbon dioxide, which he called "fixed air". In 1757, Louis Claude Cadet de Gassicourt, while investigating arsenic compounds, creates Cadet's fuming liquid, later discovered to be cacodyl oxide, considered to be the first synthetic organometallic compound. In 1758, Josep... | History of chemistry | 0.808738 |
23,590 | The van 't Hoff-Le Chatelier principle, or simply Le Chatelier's principle, explains the response of dynamic chemical equilibria to external stresses.In 1884, Hermann Emil Fischer proposed the structure of purine, a key structure in many biomolecules, which he later synthesized in 1898. He also began work on the chemis... | History of chemistry | 0.808738 |
23,591 | In 1884, Jacobus Henricus van 't Hoff published Études de Dynamique chimique (Studies in Dynamic Chemistry), a seminal study on chemical kinetics. In this work, van 't Hoff entered for the first time the field of physical chemistry. Of great importance was his development of the general thermodynamic relationship betwe... | History of chemistry | 0.808738 |
23,592 | Lavoisier made many fundamental contributions to the science of chemistry. Following his work, chemistry acquired a strict, quantitative nature, allowing reliable predictions to be made. The revolution in chemistry which he brought about was a result of a conscious effort to fit all experiments into the framework of a ... | History of chemistry | 0.808738 |
23,593 | Although many of Lavoisier's partners were influential for the advancement of chemistry as a scientific discipline, his wife Marie-Anne Lavoisier was arguably the most influential of them all. Upon their marriage, Mme. Lavoisier began to study chemistry, English, and drawing in order to help her husband in his work eit... | History of chemistry | 0.808738 |
23,594 | In addition, it contained a list of elements, or substances that could not be broken down further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulfur. His list, however, also included light and caloric, which he believed to be material substances. In the work, Lavoisier underscored the obs... | History of chemistry | 0.808738 |
23,595 | Another strong chlorine oxidant and bleach which he investigated and was the first to produce, potassium chlorate (KClO3), is known as Berthollet's Salt. Berthollet is also known for his scientific contributions to the theory of chemical equilibrium via the mechanism of reversible reactions. Lavoisier's Traité Élémenta... | History of chemistry | 0.808738 |
23,596 | For cases where no sharing was involved, Lewis in 1923 developed the electron pair theory of acids and base: Lewis redefined an acid as any atom or molecule with an incomplete octet that was thus capable of accepting electrons from another atom; bases were, of course, electron donors. His theory is known as the concept... | History of chemistry | 0.808738 |
23,597 | Lewis's model equated the classical chemical bond with the sharing of a pair of electrons between the two bonded atoms. Lewis introduced the "electron dot diagrams" in this paper to symbolize the electronic structures of atoms and molecules. Now known as Lewis structures, they are discussed in virtually every introduct... | History of chemistry | 0.808738 |
23,598 | A Swedish chemist and disciple of Dalton, Jöns Jacob Berzelius embarked on a systematic program to try to make accurate and precise quantitative measurements and to ensure the purity of chemicals. Along with Lavoisier, Boyle, and Dalton, Berzelius is known as the father of modern chemistry. In 1828 he compiled a table ... | History of chemistry | 0.808738 |
23,599 | A 100,000-year-old ochre-processing workshop was found at Blombos Cave in South Africa. It indicates that early humans had an elementary knowledge of chemistry. Paintings drawn by early humans consisting of early humans mixing animal blood with other liquids found on cave walls also indicate a small knowledge of chemis... | History of chemistry | 0.808738 |
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