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Ball-and-stick Model
In chemistry, the ball-and-stick model is a molecular model of a chemical substance which displays both the Molecular geometry, three-dimensional position of the atoms and the chemical bond, bonds between them. The atoms are typically represented by sphere (geometry), spheres, connected by rods which represent the bonds. Double bond, Double and triple bonds are usually represented by two or three curved rods, respectively, or alternately by correctly positioned sticks for the sigma bond, sigma and pi bonds. In a good model, the angles between the rods should be the same as the Bond angle, angles between the bonds, and the distances between the centers of the spheres should be proportional to the distances between the corresponding atomic nucleus, atomic nuclei. The chemical element of each atom is often indicated by the sphere's color. In a ball-and-stick model, the radius of the spheres is usually much smaller than the rod lengths, in order to provide a clearer view of the atoms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proline Model
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the Protein biosynthesis, biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO− form. The "side chain" from the Alpha and beta carbon, α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is Genetic code, encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG). Proline is the only proteinogenic secondary amino acid, amino acid which is a secondary amine, as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring. History and etymology Proline was f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Waals Radius
The van der Waals radius, ''r'', of an atom is the radius of an imaginary hard sphere representing the distance of closest approach for another atom. It is named after Johannes Diderik van der Waals, winner of the 1910 Nobel Prize in Physics, as he was the first to recognise that atoms were not simply points and to demonstrate the physical consequences of their size through the van der Waals equation of state. van der Waals volume The van der Waals volume, ''V'', also called the atomic volume or molecular volume, is the atomic property most directly related to the van der Waals radius. It is the volume "occupied" by an individual atom (or molecule). The van der Waals volume may be calculated if the van der Waals radii (and, for molecules, the inter-atomic distances, and angles) are known. For a single atom, it is the volume of a sphere whose radius is the van der Waals radius of the atom:V_ = \pi r_^3. For a molecule, it is the volume enclosed by the van der Waals surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(methyl Methacrylate)
Poly(methyl methacrylate) (PMMA) is a synthetic polymer derived from methyl methacrylate. It is a transparent thermoplastic, used as an engineering plastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Walcast, Hesalite, Plexiglas, Acrylite, Lucite, PerClax, and Perspex, among several others ( see below). This plastic is often used in sheet form as a lightweight or shatter-resistant alternative to glass. It can also be used as a casting resin, in inks and coatings, and for many other purposes. It is often technically classified as a type of glass, in that it is a non-crystalline vitreous substance—hence its occasional historic designation as ''acrylic glass''. History The first acrylic acid was created in 1843. Methacrylic acid, derived from acrylic acid, was formulated in 1865. The reaction between methacrylic acid and methanol results in the ester methyl methacrylate. It was developed in 1928 in several different la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edinburgh
Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh had a population of in , making it the List of towns and cities in Scotland by population, second-most populous city in Scotland and the List of cities in the United Kingdom, seventh-most populous in the United Kingdom. The Functional urban area, wider metropolitan area had a population of 912,490 in the same year. Recognised as the capital of Scotland since at least the 15th century, Edinburgh is the seat of the Scottish Government, the Scottish Parliament, the Courts of Scotland, highest courts in Scotland, and the Palace of Holyroodhouse, the official residence of the Monarchy of the United Kingdom, British monarch in Scotland. It is also the annual venue of the General Assembly of the Church of Scotland. The city has long been a cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ångström
The angstrom (; ) is a unit of length equal to m; that is, one ten- billionth of a metre, a hundred-millionth of a centimetre, 0.1 nanometre, or 100 picometres. The unit is named after the Swedish physicist Anders Jonas Ångström (1814–1874). It was originally spelled with Swedish letters, as Ångström and later as ångström (). The latter spelling is still listed in some dictionaries, but is now rare in English texts. Some popular US dictionaries list only the spelling ''angstrom''. The unit's symbol is Å, which is a letter of the Swedish alphabet, regardless of how the unit is spelled. However, "A" or "A.U." may be used in less formal contexts or typographically limited media. The angstrom is often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridgeshire
Cambridgeshire (abbreviated Cambs.) is a Ceremonial counties of England, ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, Northamptonshire to the west, and Bedfordshire to the south-west. The largest settlement is the city of Peterborough, and the city of Cambridge is the county town. The county has an area of and had an estimated population of 906,814 in 2022. Peterborough, in the north-west, and Cambridge, in the south, are by far the largest settlements. The remainder of the county is rural, and contains the city of Ely, Cambridgeshire, Ely in the east, Wisbech in the north-east, and St Neots and Huntingdon in the west. For Local government in England, local government purposes Cambridgeshire comprises a non-metropolitan county, with five Districts of England, districts, and the Unitary authorities of England, unitary authority area o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bottisham
Bottisham is a village and civil parish in the East Cambridgeshire district of Cambridgeshire, England, about east of Cambridge, halfway to Newmarket, Suffolk, Newmarket. According to the 2001 census it had a population of 1,983, including Chittering, Cambridgeshire, Chittering, increasing to 2,199 at the 2011 Census. Church Bottisham has overhanging cottages and the tower of the Church of the Holy Trinity which has some of the finest fourteenth-century work in the county. The tower and the chancel with its stone seats are thirteenth century but the nave and aisles and porches are all from the fourteenth. The south aisle has a stone seat for the priest, a piscina, and in its floor an ancient coffin lid. Above the arcades is a clerestory of fluted lancet windows. There is a font and three old screens of the fourteenth century, two of oak and the other of stone, with three delicate open arches before the chancel. There is an iron-bound chest of 1790, and some fragments of carve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Institution Of Great Britain
The Royal Institution of Great Britain (often the Royal Institution, Ri or RI) is an organisation for scientific education and research, based in the City of Westminster. It was founded in 1799 by the leading British scientists of the age, including Henry Cavendish and its first president, George Finch. Its foundational principles were diffusing the knowledge of, and facilitating the general introduction of useful mechanical inventions and improvements, as well as enhancing the application of science to the common purposes of life (including through teaching, courses of philosophical lectures, and experiments). Much of the Institution's initial funding and the initial proposal for its founding were given by the Society for Bettering the Conditions and Improving the Comforts of the Poor, under the guidance of philanthropist Sir Thomas Bernard and American-born British scientist Sir Benjamin Thompson, Count Rumford. Since its founding it has been based at 21 Albemarle Stree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
August Wilhelm Von Hofmann
August Wilhelm von Hofmann (8 April 18185 May 1892) was a German chemist who made considerable contributions to organic chemistry. His research on aniline helped lay the basis of the aniline-dye industry, and his research on coal tar laid the groundwork for his student Charles Mansfield's practical methods for extracting benzene and toluene and converting them into nitro compounds and amines. Hofmann's discoveries include formaldehyde, hydrazobenzene, the isonitriles, and allyl alcohol. He prepared three ethylamines and tetraethylammonium compounds and established their structural relationship to ammonia. After studying under Justus von Liebig at the University of Giessen, Hofmann became the first director of the Royal College of Chemistry, now part of Imperial College London, in 1845. In 1865 he returned to Germany to accept a position at the University of Berlin as a teacher and researcher. After his return he co-founded the German Chemical Society (''Deutsche Chemis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Model Of Methane Hofmann
A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CPK Coloring
In chemistry, the CPK coloring (for Robert Corey, Corey–Linus Pauling, Pauling–Walter Koltun, Koltun) is a popular color convention for distinguishing atoms of different chemical elements in molecular models. History August Wilhelm von Hofmann was apparently the first to introduce molecular models into organic chemistry, following August Kekule's introduction of the theory of chemical structure in 1858, and Alexander Crum Brown's introduction of printed structural formulas in 1861. At a Friday Evening Discourse at London's Royal Institution on April 7, 1865, he displayed molecular models of simple organic substances such as methane, ethane, and methyl chloride, which he had had constructed from differently colored table croquet balls connected together with thin brass tubes. Hofmann's original colour scheme (carbon = black, hydrogen = white, nitrogen = blue, oxygen = red, chlorine = green, and sulphur = yellow) has evolved into the later color schemes. In 1952, Robert C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coil Spring
A tension coil spring A coil spring is a mechanical device that typically is used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. It is made of an elastic material formed into the shape of a helix that returns to its natural length when unloaded. Under tension or compression, the material (wire) of a coil spring undergoes torsion. The spring characteristics therefore depend on the shear modulus. A coil spring may also be used as a torsion spring: in this case the spring as a whole is subjected to torsion about its helical axis. The material of the spring is thereby subjected to a bending moment, either reducing or increasing the helical radius. In this mode, it is the Young's modulus of the material that determines the spring characteristics. Spring rate A selection of conical coil springs Spring rate is the measurement of how much load (in pounds) a coil spring can hold until it compresses . The spring r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
