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Encyclopedia > Molecule
3D (left and center) and 2D (right) representations of the terpenoid molecule atisane.
3D (left and center) and 2D (right) representations of the terpenoid molecule atisane.

In chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by strong chemical bonds.[1][2] In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules. Molecules are distinguished from polyatomic ions in this strict sense. An example for the Molecule article based on Image:Atisane. ... An example for the Molecule article based on Image:Atisane. ... The space we live in is three-dimensional space. ... A 2D geometric model is a geometric model of an object as two-dimensional figure, usually on the Euclidean or Cartesian plane. ... Chemical structure of the terpenoid isopentenyl pyrophosphate. ... For other uses, see Chemistry (disambiguation). ... This box:      Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... For other uses, see Atom (disambiguation). ... 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. ... Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting primarily of carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, the halogens as... Biochemistry (from Greek: , bios, life and Egyptian kÄ“me, earth[1]) is the study of the chemical processes in living organisms. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas coloured yellow A polyatomic ion is a molecule that bears ionic groups, that is, a molecule with a charge. ...


This definition has evolved as knowledge of the structure of molecules has increased. Earlier definitions were less precise defining molecules as the smallest particles of pure chemical substances that still retain their composition and chemical properties.[3] This definition often breaks down since many substances in ordinary experience, such as rocks, salts, and metals, are composed of atoms or ions, but are not made of molecules. This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. ... Water and steam are two different forms of the same chemical substance A chemical substance is a material with a definite chemical composition. ... Look up chemical compound in Wiktionary, the free dictionary. ... This article is about the geological substance. ... This article is about common table salt. ... This article is about metallic materials. ... This article is about the electrically charged particle. ...


In the kinetic theory of gases the term molecule is often used for any gaseous particle regardless of their composition.[4] According to this definition noble gases would also be considered molecules despite the fact that they are composed of a single non-bonded atom. Kinetic theory or kinetic theory of gases attempts to explain macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. ... For other uses, see Gas (disambiguation). ... This article is about the chemical series. ...

Contents

History

The term "molecule", from the French molécule meaning "extremely minute particle," was coined by French philosopher Rene Descartes in the 1620s. Although the existence of molecules was accepted by many chemists since the early 19th century as a result of Dalton's laws of Definite and Multiple Proportions (1803-1808) and Avogadro's law (1811), there was some resistance among positivists and physicists such as Mach, Boltzmann, Maxwell, and Gibbs, who saw molecules merely as convenient mathematical constructs. The work of Perrin on Brownian motion (1911) is considered to be the final proof of the existence of molecules. 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. ... René Descartes René Descartes (IPA: , March 31, 1596 – February 11, 1650), also known as Cartesius, worked as a philosopher and mathematician. ... John Dalton John Dalton (September 6, 1766 – July 27, 1844) was an English chemist and physicist, born at Eaglesfield, near Cockermouth in Cumberland. ... This article does not cite any references or sources. ... Logical positivism grew from the discussions of Moritz Schlicks Vienna Circle and Hans Reichenbachs Berlin Circle in the 1920s and 1930s. ... Ernst Mach Ernst Mach (February 18, 1838 – February 19, 1916) was an Austrian-Czech physicist and philosopher and is the namesake for the Mach number and the optical illusion known as Mach bands. ... 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. ... James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and theoretical physicist. ... Josiah Willard Gibbs (February 11, 1839 – April 28, 1903) was an American mathematical physicist who contributed much of the theoretical foundation that led to the development of chemical thermodynamics and was one of the founders of vector analysis. ... Jean Baptiste Perrin, generally known as Jean Perrin (Lille, September 30, 1870 – April 17, New York, 1942), was a French physicist. ...


In a molecule, at least two atoms are joined by shared pairs of electrons in a covalent bond. It may consist of atoms of the same chemical element, as with oxygen (O2), or of different elements, as with water (H2O). Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules. For other uses, see Electron (disambiguation). ... Covalent redirects here. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... This article is about the chemical element and its most stable form, or dioxygen. ... H2O and HOH redirect here. ... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ... Sodium and chlorine bonding ionically to form sodium chloride. ...


No typical molecule can be defined for ionic (salts) and covalent crystals (network solids) which are composed of repeating unit cells that extend either in a plane (such as in graphite) or three-dimensionally (such as in diamond or sodium chloride). A magnified crystal of salt In chemistry, salt is a term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... This article is about the mathematical construct. ... For other uses, see Graphite (disambiguation). ... This article is about the mineral. ... R-phrases 36 S-phrases none Flash point Non-flammable Related Compounds Other anions NaF, NaBr, NaI Other cations LiCl, KCl, RbCl, CsCl, MgCl2, CaCl2 Related salts Sodium acetate Supplementary data page Structure and properties n, εr, etc. ...


The science of molecules is called molecular chemistry or molecular physics, depending on the focus. Molecular chemistry deals with the laws governing the interaction between molecules that results in the formation and breakage of chemical bonds, while molecular physics deals with the laws governing their structure and properties. In practice, however, this distinction is vague. In molecular sciences, a molecule consists of a stable system (bound state) comprising two or more atoms. Polyatomic ions may sometimes be usefully thought of as electrically charged molecules. The term unstable molecule is used for very reactive species, i.e., short-lived assemblies (resonances) of electrons and nuclei, such as radicals, molecular ions, Rydberg molecules, transition states, van der Waals complexes, or systems of colliding atoms as in Bose-Einstein condensates. Molecular physics is the study of the physical properties of molecules and of the chemical bonds between atoms that bind them into molecules. ... 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. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ... For other uses, see Atom (disambiguation). ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas coloured yellow A polyatomic ion is a molecule that bears ionic groups, that is, a molecule with a charge. ... Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... This article is about resonance in physics. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... This article is about the electrically charged particle. ... DIFFERENTIATE PARTICLES FROM NANOPARTICLE ... The transition state of a chemical reaction is a particular configuration along the reaction coordinate. ... Van der Waals bonding, also known as London force, instantaneous dipole effect, and induced dipole interaction, is an intermolecular force or interatomic force that causes an attraction between temporarily induced dipoles in nonpolar molecules and atoms. ... A Bose–Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero (0 kelvins or -273. ...


Molecular size

Most molecules are far too small to be seen with the naked eye, but there are exceptions. DNA, a macromolecule, can reach macroscopic sizes, as can molecules of many polymers. The smallest molecule is the diatomic hydrogen (H2), with an overall length of roughly twice the 74 picometres (0.74 Å) bond length. Molecules commonly used as building blocks for organic synthesis have a dimension of a few Å to several dozen Å. Single molecules cannot usually be observed by light (as noted above), but small molecules and even the outlines of individual atoms may be traced in some circumstances by use of an atomic force microscope. Some of the largest molecules are macromolecules or supermolecules. The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Illustration of a polypeptide macromolecule The term macromolecule by definition implies large molecule. In the context of biochemistry, the term may be applied to the four conventional biopolymers (nucleotides, proteins, carbohydrates, and lipids), as well as non-polymeric molecules with large molecular mass such as macrocycles. ... Macroscopic is commonly used to describe physical objects that are measurable and observable by the naked eye. ... A computer rendering of the Nitrogen Molecule, which is a diatomic molecule. ... This article is about the chemistry of hydrogen. ... One picometre is defined as 1x10-12 metres, in standard units. ... An Ã¥ngström or aangstroem (the official transliteration), or angstrom (symbol Ã…) is a non-SI unit of length that is internationally recognized, equal to 0. ... Topographic scan of a glass surface The atomic force microscope (AFM) is a very high-resolution type of scanning probe microscope, with demonstrated resolution of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. ... Illustration of a polypeptide macromolecule The term macromolecule by definition implies large molecule. In the context of biochemistry, the term may be applied to the four conventional biopolymers (nucleotides, proteins, carbohydrates, and lipids), as well as non-polymeric molecules with large molecular mass such as macrocycles. ... A supermolecule sometimes called a supramolecule is a discrete complex of two or more molecules often macromolecules that are not covalently bonded. ...


Radius

Effective molecular radius is the size a molecule displays in solution. [5]. The table of permselectivity for different substances contains examples.


Molecular formula

The empirical formula of a molecule is the simplest integer ratio of the chemical elements that constitute the compound. For example, in their pure forms, water is always composed of a 2:1 ratio of hydrogen to oxygen, and ethyl alcohol or ethanol is always composed of carbon, hydrogen, and oxygen in a 2:6:1 ratio. However, this does not determine the kind of molecule uniquely - dimethyl ether has the same ratio as ethanol, for instance. Molecules with the same atoms in different arrangements are called isomers. The empirical formula is often the same as the molecular formula but not always. For example the molecule acetylene has molecular formula C2H2, but the simplest integer ratio of elements is CH. The molecular formula reflects the exact number of atoms that compose a molecule. In chemistry, the empirical formula of a chemical compound is a simple expression of the relative number of each type of atom in it. ... The integers are commonly denoted by the above symbol. ... This article is about the mathematical concept. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about the chemistry of hydrogen. ... This article is about the chemical element and its most stable form, or dioxygen. ... This article does not cite any references or sources. ... Grain alcohol redirects here. ... For other uses, see Carbon (disambiguation). ... This article is about the chemistry of hydrogen. ... This article is about the chemical element and its most stable form, or dioxygen. ... Dimethyl ether, also known as methoxymethane, oxybismethane, methyl ether, wood ether, and DME, is a colorless gaseous ether with an ethereal odor. ... For other uses, see Atom (disambiguation). ... In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram). ... Acetylene (systematic name: ethyne) is a hydrocarbon belonging to the group of alkynes. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ...


The molecular mass can be calculated from the chemical formula and is expressed in conventional atomic mass units equal to 1/12th of the mass of a neutral carbon-12 (12C isotope) atom. For network solids, the term formula unit is used in stoichiometric calculations. The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic and molecular masses. ... For other uses, see Carbon (disambiguation). ... For other uses, see Isotope (disambiguation). ... A formula unit in chemistry is the empirical formula of an ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. ... In chemistry, stoichiometry is the study of the combination of elements in chemical reactions. ...


Molecular geometry

Main article: Molecular geometry

Molecules have fixed equilibrium geometries—bond lengths and angles— about which they continuously oscillate through vibrational and rotational motions. A pure substance is composed of molecules with the same average geometrical structure. The chemical formula and the structure of a molecule are the two important factors that determine its properties, particularly its reactivity. Isomers share a chemical formula but normally have very different properties because of their different structures. Stereoisomers, a particular type of isomers, may have very similar physico-chemical properties and at the same time very different biochemical activities. Geometry of the water molecule Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule, inferred from the spectroscopic studies of the compound. ... A standard definition of mechanical equilibrium is: A system is in mechanical equilibrium when the sum of the forces, and torque, on each particle of the system is zero. ... In mathematics, an average or central tendency of a set (list) of data refers to a measure of the middle of the data set. ... Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... Stereoisomerism is the arrangement of atoms in molecules whose connectivity remains the same but their arrangement in space is different in each isomer. ... Biochemistry (from Greek: , bios, life and Egyptian kÄ“me, earth[1]) is the study of the chemical processes in living organisms. ...


Molecular spectroscopy

Main article: Spectroscopy

Molecular spectroscopy deals with the response (spectrum) of molecules interacting with probing signals of known energy (or frequency, according to Planck's formula). Scattering theory provides the theoretical background for spectroscopy. Animation of the dispersion of light as it travels through a triangular prism. ... Familiar concepts associated with a frequency are colors, musical notes, radio/TV channels, and even the regular rotation of the earth. ... For other uses, see Frequency (disambiguation). ... A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ... Scattering theory is a branch of physics and especially of quantum mechanics whose aim is the study of scattering events. ...


The probing signal used in spectroscopy can be an electromagnetic wave or a beam of particles (electrons, positrons, etc.) The molecular response can consist of signal absorption (absorption spectroscopy), the emission of another signal (emission spectroscopy), fragmentation, or chemical changes. Electromagnetic radiation is a propagating wave in space with electric and magnetic components. ... For the novel, see The Elementary Particles. ... For other uses, see Electron (disambiguation). ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... Absorption spectroscopy refers to a wide range of techniques where one measures how much light of a particular wavelength (color) is absorbed by a sample. ... a Headline text hi today for the first time i fucked my 14 years neighbour she was very excited when she saw my dick thouh it was a bit thick and long but she gladly become agree to let me fuck her at my first stroke i broke her seal...


Spectroscopy is recognized as a powerful tool in investigating the microscopic properties of molecules, in particular their energy levels. In order to extract maximum microscopic information from experimental results, spectroscopy is often coupled with chemical computations. A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ... A quantum mechanical system can only be in certain states, so that only certain energy levels are possible. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ...


Theoretical aspects

The study of molecules by molecular physics and theoretical chemistry is largely based on quantum mechanics and is essential for the understanding of the chemical bond. The simplest of molecules is the hydrogen molecule-ion, H2+, and the simplest of all the chemical bonds is the one-electron bond. H2+ is composed of two positively-charged protons and one negatively-charged electron bound by photon exchange, which means that the Schrödinger equation for the system can be solved more easily due to the lack of electron–electron repulsion. With the development of fast digital computers, approximate solutions for more complicated molecules became possible and are one of the main aspects of computational chemistry. Molecular physics is the study of the physical properties of molecules and of the chemical bonds between atoms that bind them into molecules. ... Theoretical chemistry involves the use of physics to explain or predict chemical phenomena. ... Fig. ... 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. ... 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. ... For other uses, see Proton (disambiguation). ... For other uses, see Electron (disambiguation). ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... For a non-technical introduction to the topic, please see Introduction to quantum mechanics. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ...


When trying to define rigorously whether an arrangement of atoms is "sufficiently stable" to be considered a molecule, IUPAC suggests that it "must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state".[1] This definition does not depend on the nature of the interaction between the atoms, but only on the strength of the interaction. In fact, it includes weakly-bound species that would not traditionally be considered molecules, such as the helium dimer, He2, which has one vibrational bound state but is so loosely bound that it is only likely to be observed at very low temperatures. A potential energy surface is generally used within the adiabatic or Born–Oppenheimer approximation in quantum mechanics and statistical mechanics to model chemical reactions and interactions in simple chemical and physical systems. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... Sucrose, or common table sugar, is composed of glucose and fructose. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ...


Etymology

According to Merriam-Webster and the Online Etymology Dictionary, the word "molecule" derives from the Latin "moles" or small unit of mass. Merriam-Webster, originally known as the G. & C. Merriam Company of Springfield, Massachusetts, is a United States company that publishes reference books, especially dictionaries that are descendants of Noah Websters An American Dictionary of the English Language (1828). ... An editor has expressed a concern that the subject of the article does not satisfy the notability guideline for Web content. ... For other uses, see Latin (disambiguation). ... The mole (symbol: mol) is the SI base unit that measures an amount of substance. ...

  • Molecule (1794) - "extremely minute particle," from Fr. molécule (1678), from Mod.L. molecula, dim. of L. moles "mass, barrier". A vague meaning at first; the vogue for the word (used until late 18th century only in Latin form) can be traced to the philosophy of Descartes.

Most molecules are made up of multiple atoms; for example, a molecule of water is a combination of two hydrogen atoms and one oxygen atom. The term 'molecule' in gases has been used as a synonym for the fundamental particles of the gas, whatever their structure. This definition results in a few types of gases (for example inert elements that do not form compounds, such as neon), which has 'molecules' consisting of only a single atom.[6] René Descartes René Descartes (IPA: , March 31, 1596 – February 11, 1650), also known as Cartesius, worked as a philosopher and mathematician. ... This article is about the chemistry of hydrogen. ... This article is about the chemical element and its most stable form, or dioxygen. ... For other uses, see Neon (disambiguation). ...


See also

The backbone dihedral angles are included in the molecular model of a protein. ... Covalent redirects here. ... A space-filling model of the diatomic molecule dinitrogen, N2. ... 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. ... Geometry of the water molecule Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule, inferred from the spectroscopic studies of the compound. ... The molecular Hamiltonian is an operator in quantum chemistry and atomic, molecular, and optical physics which describes the motions of electrons and nuclei in a polyatomic molecule. ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... In chemistry, a nonpolar compound is one that does not have concentrations of positive or negative electric charge. ... A commonly-used example of a polar compound is water (H2O). ... The original list from this page has been split into the following three lists, as the number of compounds became too long. ... This is a list of molecules that have been detected in the interstellar medium, grouped by the number of component atoms. ...

References

  1. ^ a b International Union of Pure and Applied Chemistry (1994). "molecule". Compendium of Chemical Terminology Internet edition.
  2. ^ Pauling, Linus (1970). General Chemistry. New York: Dover Publications, Inc.. ISBN 0-486-65622-5. 
    Ebbin, Darrell, D. (1990). General Chemistry, 3th Ed.. Boston: Houghton Mifflin Co.. ISBN 0-395-43302-9. 
    Brown, T.L. (2003). Chemistry – the Central Science, 9th Ed.. New Jersey: Prentice Hall. ISBN 0-13-066997-0. 
    Chang, Raymond (1998). Chemistry, 6th Ed.. New York: McGraw Hill. ISBN 0-07-115221-0. 
    Zumdahl, Steven S. (1997). Chemistry, 4th ed.. Boston: Houghton Mifflin. ISBN 0-669-41794-7. 
  3. ^ Molecule Definition (Frostburg State University)
  4. ^ E.g. see [1]
  5. ^ [www.wipo.int/pctdb/en/wo.jsp?IA=WO1999030745&DISPLAY=DESC -(WO/1999/030745) DOTA-BIOTIN DERIVATIVES
  6. ^ Chandra, Sulekh. Comprehensive Inorganic Chemistry. New Age Publishers. ISBN 8122415121. 

IUPAC logo The International Union of Pure and Applied Chemistry (IUPAC) (Pronounced as eye-you-pack) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry. ... Compendium of Chemical Terminology (ISBN 0-86542-684-8) is a book published by IUPAC containing internationally accepted definitions for terms in chemistry. ...

External links

  • MoleClues - Molecular science for kids
  • Molecular Frontiers - Home Page of Molecular Frontiers Foundation
  • Molecule of the Month - School of Chemistry, University of Bristol
  • Antibody Molecule - The National Health Museum
  • Data Book of Molecules - Home Page for Learning Environmental Chemistry
Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... For the novel, see The Elementary Particles. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... For other uses, see Quark (disambiguation). ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... The charm quark is a second-generation quark with a charge of +(2/3)e. ... The strange quark is a second-generation quark with a charge of -(1/3)e and a strangeness of −1. ... The top quark is the third-generation up-type quark with a charge of +(2/3)e. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... In physics, a lepton is a particle with spin-1/2 (a fermion) that does not experience the strong interaction (that is, the strong nuclear force). ... For other uses, see Electron (disambiguation). ... 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 muon (from the letter mu (μ)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. ... An antimuon is the antiparticle of the muon. ... The tau lepton (often called the tau or occasionally the tauon) is a negatively charged elementary particle with a lifetime of 3×10−13 seconds and a high mass of 1777 MeV (compared to 939 MeV for protons and 0. ... An antitauon is the antiparticle of the tauon. ... The neutrino is an elementary particle. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... The neutrino is an elementary particle. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... The neutrino is an elementary particle. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... In particle physics, bosons, named after Satyendra Nath Bose, are particles having integer spin. ... Gauge bosons are bosonic particles which act as carriers of the fundamental forces of Nature. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... In physics, Faddeev-Popov ghost ci is a field that violates the spin-statistics relation. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ... A hadron, in particle physics, is a subatomic particle which experiences the nuclear force. ... Combinations of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. ... Baryon decuplet: Spin=3/2 Baryon octet: Spin=1/2 This is a list of baryons. ... In particle physics, a hyperon is any subatomic particle which is a baryon (and hence a hadron and a fermion) with non-zero strangeness, but with zero charm and zero bottomness. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... For other uses, see Proton (disambiguation). ... This article or section does not adequately cite its references or sources. ... The Delta baryon is a relatively light 1,232 MeV/c² baryon which contains only up (u) and down (d) quarks in a combination whose total spin is 3/2 and its ground state parity is +. All varieties of Δ quickly decay via the strong force into an ordinary nucleon plus... Properties In particle physics, the omega minus (Ω−) is a type of baryon (more specifically, a hyperon). ... The cascade B baryon particle, also known as Ξ-b, was recently discovered by D0 and CDF experiments at Fermilab. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... A list of mesons. ... In high energy physics, a quarkonium (pl. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: π0, π+ and π−. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ... In particle physics, Kaons (also called K-mesons and denoted K) are a group of four mesons distinguished by the fact that they carry a quantum number called strangeness. ... In particle physics, a rho meson is a short-lived hadronic particle that is an isospin triplet whose three states are denoted as . After the pions and kaons, the rho mesons are the lightest strongly interacting particle with a mass of roughly 770 MeV for all three states. ... The title given to this article is incorrect due to technical limitations. ... The upsilon particle () is a flavorless meson formed from a bottom quark and its antiparticle. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... For other uses, see Atom (disambiguation). ... An exotic atom is the anologue of a normal atom in which one or more of the electrons are replaced by other negative particles, such as a muon or a pion, or the positively charged nucleus is replaced by other positively charged elementary particles, or both. ... Positronium (Ps) is a system consisting of an electron and its anti-particle, a positron, bound together into an exotic atom. The orbit of the two particles and the set of energy levels is similar to that of the hydrogen atom (electron and proton). ... This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. ... In supersymmetry, it is proposed that every fermion should have a partner boson, known as its Superpartner. ... The axino is a hypothetical elementary particle predicted by some theories of particle physics. ... Dilatino is the superpartner of the dilaton. ... In particle physics, chargino refers to a charged superpartner, i. ... A gluino is a subatomic particle, the fermion superpartner of the gluon predicted by supersymmetry. ... The gravitino is the hypothetical supersymmetric partner of the graviton, as predicted by theories combining general relativity and supersymmetry, i. ... In particle physics, a higgsino is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. ... In particle physics, the neutralino is a hypothetical particle and part of the doubling of the menagerie of particles predicted by supersymmetric theories. ... In particle physics, a sfermion is any of the class of spin-0 superpartners of ordinary fermions appearing in supersymmetric extensions to the Standard Model. ... In particle physics, a slepton is a hypothetical bosonic partner of a lepton whose existence is implied by supersymmetry. ... In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... The axion is an exotic subatomic particle postulated by Peccei-Quinn theory to resolve the strong-CP problem in quantum chromodynamics (QCD). ... In theoretical physics, dilaton originally referred to a theoretical scalar field; as a photon refers in one sense to the electromagnetic field. ... In particle and condensed matter physics, Goldstone bosons (also known as Nambu-Goldstone bosons) are bosons that appear in models with spontaneously broken symmetry. ... This article is about the hypothetical particle. ... The Higgs boson, also known as the God particle, is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... A tachyon (from the Greek (takhús), meaning swift, fast) is any hypothetical particle that travels at superluminal velocity. ... In particle physics, the X and Y bosons are hypothetical elementary particles analogous to the W and Z bosons, but corresponding to a new type of force, such as the forces predicted by grand unified theory. ... It has been suggested that this article or section be merged with Z boson. ... In particle physics, a Z boson (or Z-prime boson) refers to a hypothetical new neutral gauge boson (named in analogy with the Standard Model Z boson). ... A sterile particle does not have any charge known to us. ... A regular meson made from a quark (q) and antiquark (q-bar) with spins s2 and s1 respectively and having an overall angular momentum L Exotic hadrons are subatomic particles made of quarks (and possibly gluons), but which do not fit into the usual schema of hadrons. ... Ordinary baryons are bound states of 3 quarks. ... A pentaquark is a subatomic particle consisting of a group of five quarks (compared to three quarks in normal baryons and two in mesons), or more specifically four quarks and one anti-quark. ... Identities and classification of possible tetraquark mesons. ... In particle physics, a glueball is a particle containing no valence quarks. ... A tetraquark is a subatomic particle composed of four quarks. ... A mesonic molecule is a set of two or more mesons bound together by the strong force. ... In physics, a quasiparticle refers to a particle-like entity arising in certain systems of interacting particles. ... Side view of an α-helix of alanine residues in atomic detail. ... This page is about the quasiparticle. ... There is a place named Magnon (pronunciation: ma-nyon) in Gabon, see Magnon, Gabon A magnon is a collective excitation of the electrons spin structure in a crystal lattice. ... Normal modes of vibration progression through a crystal. ... In physics, the plasmon is the quasiparticle resulting from the quantization of plasma oscillations just as photons and phonons are quantizations of light and sound waves, respectively. ... This article is in need of attention. ... In solid-state physics, a polaron is formed when a moving charge (typically an electron or a hole) in a crystal with some ionic character polarizes (by its electric field) the lattice around it. ... This article is about matter in physics and chemistry. ... Domains and Kingdoms Nanobes Acytota Cytota Bacteria Neomura Archaea Eukaryota Bikonta Apusozoa Rhizaria Excavata Archaeplastida Rhodophyta Glaucophyta Plantae Heterokontophyta Haptophyta Cryptophyta Alveolata Unikonta Amoebozoa Opisthokonta Choanozoa Fungi Animalia An ericoid mycorrhizal fungus Life on Earth redirects here. ... An example of a system: The nervous system. ... This article is about the biological unit. ... Biological tissue is a group of cells that perform a similar function. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Schematic of typical animal cell, showing subcellular components. ... For other uses, see Atom (disambiguation). ... Helium atom (schematic) Showing two protons (red), two neutrons (green) and two electrons (yellow). ... Elementary particles An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. ... For the novel, see The Elementary Particles. ...

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Water molecule structure (1773 words)
The molecule is clearly not spherical, however, with about a ±5% variation in van der Waals diameter dependent on the axis chosen; approximately tetrahedrally placed slight indentations being apparent opposite the (putative) electron pairs.
Simplified models for the water molecule have been developed to agree with particular physical properties (for example, agreement with the critical parameters) but they are not robust and resultant data are often very sensitive to the precise model parameters [206].
Water molecules each possess a strongly nucleophilic oxygen atom that enables many of life‘s reactions, as well as ionizing to produce reactive hydrogen and hydroxide ions.
Molecule - MSN Encarta (2859 words)
For a molecule with four atoms, the central atom lies in the middle of a triangle formed by the three surrounding atoms.
In a water molecule, the central oxygen atom bonds to two surrounding hydrogen atoms and is left with one nonbonding pair in its valence shell.
Instead of forming a straight line, the water molecule follows the pattern for a molecule with four atoms, with a central atom in the middle of a triangle formed by the surrounding atoms.
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