Electron

Theoretical estimates of the electron density for the first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density
Composition	Elementary particle
Family	Fermion
Group	Lepton
Generation	First
Interaction	Gravity, Electromagnetic, Weak
Antiparticle	Positron
Theorized	G. Johnstone Stoney (1874)
Discovered	J.J. Thomson (1897)
Symbol	e−, β−
Mass	9. A hydrogen atom is an atom of the chemical element Hydrogen. The electrically neutral In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their In Particle physics, a generation is a division of the Elementary particles Between generations particles differ only by their Mass. In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms Gravitation is a natural Phenomenon by which objects with Mass attract one another In Physics, the electromagnetic force is the force that the Electromagnetic field exerts on electrically charged particles The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. George Johnstone Stoney ( February 15, 1826 &ndash July 5, 1911) was an Anglo-Irish Physicist most famous for introducing Sir Joseph John “JJ” Thomson, OM, FRS (18 December 1856 &ndash 30 August 1940 was a British Physicist and Nobel laureate 109 382 15(45) × 10–31 kg[1] 5. 485 799 09(27) × 10–4 u 1⁄1822. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express 888 4843(11) u 0. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express 510 998 918(44) MeV/c2
Electric charge	–1. The elementary charge, usually denoted e, is the Electric charge carried by a single Proton, or equivalently the negative of the electric charge carried 602 176 487(40) × 10–19 C[2]
Magnetic moment	1. The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb. In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current 0011596521859(38) μB
Spin	½
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The electron is a fundamental subatomic particle that carries a negative electric charge. In Atomic physics, the Bohr magneton (symbol \mu_\mathrm{B} is named after the Physicist Niels Bohr. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made A subatomic particle is an elementary or composite Particle smaller than an Atom. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. It is a spin ½ lepton that participates in electromagnetic interactions, and its mass is approximately 1 / 1836 of that of the proton. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their In Physics, the electromagnetic force is the force that the Electromagnetic field exerts on electrically charged particles The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive Together with atomic nuclei, which consist of protons and neutrons, electrons make up atoms. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Their interaction with adjacent nuclei is the main cause of chemical bonding. A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic

Contents 1 History 2 Classification 3 Properties and behavior 4 Visualisation 5 Electrons in chemistry 6 In practice 6.1 In the universe 6.2 In industry 6.3 In the laboratory 6.4 In medicine 7 In theory 8 Notes 9 See also 10 External links

History

The name electron comes from the Greek word for amber, ήλεκτρον. Amber is Fossil tree Resin, which is appreciated for its color and beauty This material played an essential role in the discovery of electrical phenomena. The ancient Greeks knew, for example, that rubbing a piece of amber with fur left an electric charge on its surface, which could then create a spark when brought close to a grounded object. For more about the history of the term electricity, see History of electricity.

The electron as a unit of charge in electrochemistry was posited by G. Johnstone Stoney in 1874, who also coined the term electron in 1894. George Johnstone Stoney ( February 15, 1826 &ndash July 5, 1911) was an Anglo-Irish Physicist most famous for introducing

In this paper an estimate was made of the actual amount of this most remarkable fundamental unit of electricity, for which I have since ventured to suggest the name electron.

—Stoney, George Johnstone (October 1894). George Johnstone Stoney ( February 15, 1826 &ndash July 5, 1911) was an Anglo-Irish Physicist most famous for introducing "Of the "Electron," or Atom of Electricity". Philosophical Magazine 38 (5): 418–420. The Philosophical Magazine is arguably the world’s oldest commercially published Scientific journal.  

During the late 1890s a number of physicists posited that electricity could be conceived of as being made of discrete units, which were given a variety of names, but the reality of these units had not been confirmed in a compelling way.

The discovery that the electron was a subatomic particle was made in 1897 by J.J. Thomson at the Cavendish Laboratory at Cambridge University, while he was studying cathode ray tubes. A subatomic particle is an elementary or composite Particle smaller than an Atom. Sir Joseph John “JJ” Thomson, OM, FRS (18 December 1856 &ndash 30 August 1940 was a British Physicist and Nobel laureate The Cavendish Laboratory is the University of Cambridge 's Department of Physics, and is part of the university's School of Physical Sciences The University of Cambridge (often Cambridge University) located in Cambridge, England, is the second-oldest university in the The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or A cathode ray tube is a sealed glass cylinder in which two electrodes are separated by a vacuum. When a voltage is applied across the electrodes, cathode rays are generated, causing the tube to glow. Through experimentation, Thomson discovered that the negative charge could not be separated from the rays (by the application of magnetism), and that the rays could be deflected by an electric field. He concluded that these rays, rather than being waves, were composed of negatively charged particles he called "corpuscles". He measured their mass-to-charge ratio and found it to be over a thousand times smaller than that of a hydrogen ion, suggesting that they were either very highly charged or very small in mass. Later experiments by other scientists upheld the latter conclusion. Their mass-to-charge ratio was also independent of the choice of cathode material and the gas originally in the vacuum tube. This led Thomson to conclude that they were universal among all materials.

The electron's charge was carefully measured by R. A. Millikan in his oil-drop experiment of 1909. Robert Andrews Millikan (March 22 1868 – December 19 1953 was an American experimental physicist, and Nobel laureate in physics for his measurement The Purpose of Robert Millikan and Harvey Fletcher 's oil-drop experiment (1909 was to measure the Electric charge of the Electron

The periodic law states that the chemical properties of elements largely repeat themselves periodically and is the foundation of the periodic table of elements. The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is The law itself was initially explained by the atomic mass of the element. The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass However, as there were anomalies in the periodic table, efforts were made to find a better explanation for it. In 1913, Henry Moseley introduced the concept of the atomic number and explained the periodic law in terms of the number of protons each element has. Henry Gwyn Jeffreys Moseley ( November 23, 1887 – August 10, 1915) was an English physicist. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is In the same year, Niels Bohr showed that electrons are the actual foundation of the table. Niels Henrik David Bohr (nels ˈb̥oɐ̯ˀ in Danish 7 October 1885 – 18 November 1962 was a Danish Physicist who made fundamental contributions to understanding In 1916, Gilbert Newton Lewis explained the chemical bonding of elements by electronic interactions. Gilbert Newton Lewis ( October 23, 1875 - March 23, 1946) was a famous American physical chemist known for the discovery

Classification

The electron is in the class of subatomic particles called leptons, which are believed to be fundamental particles. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made

As with all particles, electrons can also act as waves. This is called the wave-particle duality, also known by the term complementarity coined by Niels Bohr, and can be demonstrated using the double-slit experiment. In Physics and Chemistry, wave–particle duality is the concept that all Matter and Energy exhibits both Wave -like and In Physics, complementarity is a basic principle of quantum theory closely identified with the Copenhagen interpretation, and refers to effects such Niels Henrik David Bohr (nels ˈb̥oɐ̯ˀ in Danish 7 October 1885 – 18 November 1962 was a Danish Physicist who made fundamental contributions to understanding

The antiparticle of an electron is the positron, which has positive rather than negative charge. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. The discoverer of the positron, Carl D. Anderson, proposed calling standard electrons negatrons, and using electron as a generic term to describe both the positively and negatively charged variants. Carl David Anderson ( 3 September 1905 &ndash 11 January 1991) was an American Physicist. This usage of the term "negatron" is still occasionally encountered today, and it may also be shortened to "negaton". ^[3]

Properties and behavior

Electrons have an electric charge of −1.602 × 10⁻¹⁹ C, a mass of 9.11 × 10⁻³¹ kg based on charge/mass measurements equivalent to a rest mass of about 0. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. This page is a progressive and labeled list of the SI Charge orders of magnitude with certain examples appended to some list objects To help compare different orders of magnitude, the following list describes various Mass levels between 10&minus36&thinsp kg and 1053&thinspkg 511 MeV/c². The mass of the electron is approximately ¹/₁₈₃₆ of the mass of the proton. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The common electron symbol is e⁻. ^[1] The electron is thought to be stable on theoretical grounds; the lowest known experimental upper bound for its mean lifetime is 4.6×10²⁶ years, with a 90% confidence interval (see Particle decay). Given an assembly of elements the number of which decreases ultimately to zero the lifetime (also called the mean lifetime) is a certain number that characterizes the rate Seconds Years See also Natural history Geologic Particle decay is the spontaneous process of one Elementary particle transforming into other elementary particles

According to quantum mechanics, electrons can be represented by wavefunctions, from which a calculated probabilistic electron density can be determined. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons A wave function or wavefunction is a mathematical tool used in Quantum mechanics to describe any physical system Electron density is the measure of the Probability of an Electron being present at a specific location The orbital of each electron in an atom can be described by a wavefunction. An atomic orbital is a Mathematical function that describes the wave-like behavior of an electron in an atom Based on the Heisenberg uncertainty principle, the exact momentum and position of the actual electron cannot be simultaneously determined. In Quantum physics, the Heisenberg uncertainty principle states that locating a particle in a small region of space makes the Momentum of the particle uncertain In Classical mechanics, momentum ( pl momenta SI unit kg · m/s, or equivalently N · s) is the product This is a limitation which, in this instance, simply states that the more accurately we know a particle's position, the less accurately we can know its momentum, and vice versa.

The electron has spin ½ and is a fermion (it follows Fermi-Dirac statistics). In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In Statistical mechanics, Fermi-Dirac statistics is a particular case of Particle statistics developed by Enrico Fermi and Paul Dirac that In addition to its intrinsic angular momentum, an electron has an intrinsic magnetic moment along its spin axis. In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current

Electrons in an atom are bound to that atom, while electrons moving freely in vacuum, space or certain media are free electrons that can be focused into an electron beam. Cathode rays (also called an electron beam or e-beam) are streams of Electrons observed in Vacuum tubes i When free electrons move, there is a net flow of charge, and this flow is called an electric current. In Graph theory, a flow network is a directed graph where each edge has a capacity and each edge receives a Flow. Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. The drift velocity of electrons in metal wires is on the order of millimetres per second. The drift velocity is the average Velocity that a particle such as an Electron, attains due to an Electric field. However, the speed at which a current at one point in a wire causes a current in other parts of the wire, the velocity of propagation, is typically 75% of light speed.

In some superconductors, pairs of electrons move as Cooper pairs in which their motion is coupled to nearby matter via lattice vibrations called phonons. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance In Condensed matter physics, a Cooper pair is the name given to electrons that are bound together at low temperatures in a certain manner first described in 1956 by In Physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the Atomic lattice of a Solid The distance of separation between Cooper pairs is roughly 100 nm.

A body has an electric charge when that body has more or fewer electrons than are required to balance the positive charge of the nuclei. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. When there is an excess of electrons, the object is said to be negatively charged. When there are fewer electrons than protons, the object is said to be positively charged. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive When the number of electrons and the number of protons are equal, their charges cancel each other and the object is said to be electrically neutral. A macroscopic body can develop an electric charge through rubbing, by the phenomenon of triboelectricity. Macroscopic is commonly used to describe physical objects that are measurable and observable by the Naked eye. A phenomenon (from Greek φαινόμενoν, pl φαινόμενα - phenomena) is any observable occurrence Triboelectric Series Materials are often listed in order of the polarity of charge separation when they are touched with another object

When electrons and positrons collide, they annihilate each other and produce pairs of high-energy photons or other particles. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Electron-positron annihilation occurs when an Electron and a Positron (the electron's anti-particle) collide In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena On the other hand, high-energy photons may transform into an electron and a positron by a process called pair production, but only in the presence of a nearby charged particle, such as a nucleus. See also Electron-positron annihilation Meitner–Hupfeld effect Pair instability supernova

The electron is currently described as a fundamental or elementary particle. In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made It has no known substructure. In Particle physics, preons are postulated "point-like" particles conceived to be subcomponents of Quarks and Leptons The word was coined Hence, for convenience, it is usually defined or assumed to be a point-like mathematical point charge, with no spatial extension. A point charge is an idealized model of a particle which has an Electric charge. Space is the extent within which Matter is physically extended and objects and Events have positions relative to one another However, when a test particle is forced to approach an electron, we measure changes in its properties (charge and mass). Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object This effect is common to all elementary particles. Current theory suggests that this effect is due to the influence of vacuum fluctuations in its local space, so that the properties measured from a significant distance are considered to be the sum of the bare properties and the vacuum effects (see renormalization). In Physics, a virtual particle is a particle that exists for a limited time and space introducing uncertainty in their energy and momentum due to the Heisenberg Uncertainty In Quantum field theory, the Statistical mechanics of fields and the theory of self-similar geometric structures renormalization refers to a collection

The "classical electron radius" is 2. The classical electron radius, also known as the Lorentz radius or the Thomson scattering length is based on a classical (i 8179 × 10⁻¹⁵ m. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International This is the radius that is inferred from the electron's electric charge, by using the classical theory of electrodynamics alone, ignoring quantum mechanics. Classical electromagnetism (or classical electrodynamics) is a theory of Electromagnetism that was developed over the course of the 19th century most prominently Classical electromagnetism (or classical electrodynamics) is a theory of Electromagnetism that was developed over the course of the 19th century most prominently Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons (In modern physics, the electron is believed to be a point particle, thus its actual radius is zero. A point particle (or point-like, often spelled pointlike) is an idealized object heavily used in Physics. ) Classical electrodynamics (Maxwell's electrodynamics) is the older concept that is widely used for practical applications of electricity, electrical engineering, semiconductor physics, and electromagnetics. Classical electromagnetism (or classical electrodynamics) is a theory of Electromagnetism that was developed over the course of the 19th century most prominently James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Quantum electrodynamics, on the other hand, is useful for applications involving modern particle physics and some aspects of optical, laser and quantum physics. Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics.

Based on current theory, the speed of an electron can approach, but never reach, c (the speed of light in a vacuum). This limitation is attributed to Einstein's theory of special relativity which defines the speed of light as a constant within all inertial frames. Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial In Physics, an inertial frame of reference is a Frame of reference which belongs to a set of frames in which Physical laws hold in the same and simplest However, when relativistic electrons are injected into a dielectric medium such as water, where the local speed of light is significantly less than c, the electrons (temporarily) travel faster than light in the medium. Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. As they interact with the medium, they generate a faint bluish light called Cherenkov radiation. Čerenkov radiation (also spelled Cerenkov or Cherenkov) is Electromagnetic radiation emitted when a charged particle (such as an

The effects of special relativity are based on a quantity known as γ or the Lorentz factor. Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial Gamma (uppercase &Gamma, lowercase γ Γάμμα is the third letter of the Greek alphabet. The Lorentz factor or Lorentz term appears in several equations in Special relativity, including Time dilation, Length contraction, and the γ is a function of v, the coordinate velocity of the particle. It is defined as:

The kinetic energy necessary to accelerate an electron is:

For example, the Stanford linear accelerator can accelerate an electron to roughly 51 GeV [1]. The Stanford Linear Accelerator Center ( SLAC) is a United States Department of Energy National Laboratory operated by Stanford University under This gives a gamma of 100,000, since the mass of an electron is 0. 51 MeV/c² (the relativistic momentum of this electron is 100,000 times the classical momentum of an electron at the same speed). Solving the equation above for the speed of the electron (and using an approximation for large γ) gives:

The de Broglie wavelength of a particle is λ=h/p where h is Planck's constant and p is momentum. In Physics, the de Broglie hypothesis (pronounced /brœj/ as French breuil close to "broy" is the statement that all Matter (any object has a Wave The Planck constant (denoted h\ is a Physical constant used to describe the sizes of quanta. At low (e. g photoelectron) energies this determines the size of atoms, and at high (e. g. electron microscope) energies this makes the Bragg angles for electron diffraction (co-discovered by J. J. Thomson's son G. P. Thomson) well under one degree. In Physics, Bragg's law is the result of experiments into the Diffraction of X-rays or neutrons off Crystal surfaces at certain angles Electron diffraction is a technique used to study matter by firing Electrons at a sample and observing the resulting Interference pattern Sir Joseph John “JJ” Thomson, OM, FRS (18 December 1856 &ndash 30 August 1940 was a British Physicist and Nobel laureate Sir George Paget Thomson, FRS ( May 3, 1892 &ndash September 10, 1975) was an English Physicist and Since momentum is mass times proper-velocity w=γv, we have

For the 51 GeV electron above, proper-velocity is approximately γc, making the wavelength of those electrons small enough to explore structures well below the size of an atomic nucleus. Proper-velocity, the distance traveled per unit time elapsed on the clocks of a traveling object equals coordinate velocity at low speeds

Visualisation

The first video images of an electron were captured by a team at Lund University in Sweden in February 2008. To capture this event, the scientists used extremely short flashes of light. To produce this light, newly developed technology for generating short pulses from intense laser light, called attosecond pulses, allowed the team at the university’s Faculty of Engineering to capture the electron's motion for the first time.

"It takes about 150 attoseconds for an electron to circle the nucleus of an atom. An attosecond is related to a second as a second is related to the age of the universe," explained Johan Mauritsson, an assistant professor in atomic physics at the Faculty of Engineering, Lund University.

[2] Video is available here: [3]

Electrons in chemistry

In 1913, Niels Bohr showed that electrons are the actual foundation of the periodic table of chemical elements, and, in 1916, Gilbert Newton Lewis explained the chemical bonding of elements by electronic interactions. Niels Henrik David Bohr (nels ˈb̥oɐ̯ˀ in Danish 7 October 1885 – 18 November 1962 was a Danish Physicist who made fundamental contributions to understanding Gilbert Newton Lewis ( October 23, 1875 - March 23, 1946) was a famous American physical chemist known for the discovery A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic From these discoveries it has become clear that electrons, in particular those orbiting on the outer shell of the atom, play a fundamental part in chemical structure and chemical interactions, and that these interactions form the central part of chemistry, without which it could not even exist. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Chemical structure refers to Molecular geometry, Electronic structure and Crystal structure. Interaction is a kind of action that occurs as two or more objects have an Effect upon one another Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties

In practice

In the universe

Scientists believe that the number of electrons existing in the known universe is at least 10⁷⁹. The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy This number amounts to an average density of about one electron per cubic metre of space. CM3 redirects here If you were looking for the 3rd game in the Cooking Mama series abbreviated as CM3 see here. Astronomers have estimated that 90% of the mass of atoms in the universe is hydrogen, which is made of one electron and one proton. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1

In industry

Electron beams are used in welding, lithography, scanning electron microscopes and transmission electron microscopes. Cathode rays (also called an electron beam or e-beam) are streams of Electrons observed in Vacuum tubes i Electron beam welding (EBW is a fusion Welding process in which a beam of high-velocity Electrons is applied to the materials being joined Electron beam lithography (often abbreviated as e-beam lithography) is the practice of scanning a beam of Electrons in a patterned fashion across a surface covered The scanning electron microscope ( SEM) is a type of Electron microscope that images the sample surface by scanning it with a high-energy beam of Electrons LEED and RHEED are surface-imaging techniques that use electrons. Low-energy electron diffraction (LEED is a technique used to characterize the structures of surfaces Reflection high-energy electron diffraction ( RHEED) is a technique used to characterize the surface of crystalline materials

Electrons are also at the heart of cathode ray tubes, which are used extensively as display devices in laboratory instruments, computer monitors and television sets. The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video In a photomultiplier tube, one photon strikes the photocathode, initiating an avalanche of electrons that produces a detectable current. Photomultiplier tubes ( photomultipliers or PMT s for short members of the class of Vacuum tubes and more specifically Phototubes are extremely

In the laboratory

The uniquely high charge-to-mass ratio of electrons means that they interact strongly with atoms, and are easy to accelerate and focus with electric and magnetic fields. Hence some of today's aberration-corrected transmission electron microscopes use 300keV electrons with velocities greater than the speed of light in water, wavelengths below 2 picometers, transverse coherence-widths over a nanometer, and longitudinal coherence-widths 100 times that. Transmission Electron Aberration-corrected Microscope or TEAM is a $100 million U An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image This allows such microscopes to image scattering from individual atomic-nuclei (HAADF) as well as interference-contrast from solid-specimen exit-surface deBroglie-phase (HRTEM) with lateral point-resolutions down to 60 picometers. Annular dark-field imaging is a method of mapping samples in a Scanning transmission electron microscope (STEM High Resolution Transmission Electron Microscopy ( HRTEM) is an imaging mode of the Transmission electron microscope (TEM that allows the imaging of the crystallographic Image resolution describes the detail an Image holds The term applies equally to Digital images film images and other types of images Magnifications approaching 100 million are needed to make the resulting image detail comfortably visible to the naked eye.

Quantum effects of electrons are also used in the scanning tunneling microscope to study features on solid surfaces with lateral-resolution at the atomic scale (around 200 picometers) and vertical-resolutions much better than that. Scanning tunneling microscope (STM is a powerful technique for viewing surfaces at the atomic level In such microscopes, the quantum tunneling is strongly dependent on tip-specimen separation, and, precise control of the separation (vertical sensitivity) is made possible with a piezoelectric scanner. In Quantum mechanics, quantum tunnelling is a nanoscopic phenomenon in which a particle violates the principles of Classical mechanics by penetrating a Piezoelectricity is the ability of some materials (notably Crystals and certain Ceramics including bone to generate an Electric potential in response to

In medicine

In radiation therapy, electron beams are used for treatment of superficial tumours. Radiation therapy (or radiotherapy) is the medical use of Ionizing radiation as part of Cancer treatment to control Malignant Superficial is a general term meaning "regarding the Surface " often Metaphorically Both in the literal as in the metaphorical sense the term has often a

In theory

In Dirac's model, an electron is defined to be a mathematical point, a point-like, charged "bare" particle surrounded by a sea of interacting pairs of virtual particles and antiparticles. In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. These provide a correction of just over 0. 1% to the predicted value of the electron's gyromagnetic ratio from exactly 2 (as predicted by Dirac's single-particle model). In Physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines of a particle or system is the Ratio of its The extraordinarily precise agreement of this prediction with the experimentally determined value is viewed as one of the great achievements of modern physics. ^[4]

In the Standard Model of particle physics, the electron is the first-generation charged lepton. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them In Particle physics, a generation is a division of the Elementary particles Between generations particles differ only by their Mass. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their It forms a weak isospin doublet with the electron neutrino; these two particles interact with each other through both the charged and neutral current weak interaction. The weak isospin in Particle physics is a quantum number relating to the Weak interaction, and parallels the idea of Isospin under the Strong Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature The electron is very similar to the two more massive particles of higher generations, the muon and the tau lepton, which are identical in charge, spin, and interaction, but differ in mass. 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 The tau lepton (often called the tau, tau particle, or occasionally the tauon; symbol) is a negatively charged Elementary particle with In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms

The antimatter counterpart of the electron is the positron. In Particle physics and Quantum chemistry, antimatter is the extension of the concept of the Antiparticle to Matter, where antimatter is composed The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. The positron has the same amount of electrical charge as the electron, except that the charge is positive. It has the same mass and spin as the electron. When an electron and a positron meet, they may annihilate each other, giving rise to two gamma-ray photons emitted at roughly 180° to each other. Annihilation is defined as "total destruction" or "complete obliteration" of an object having its root in the Latin nihil (nothing Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions If the electron and positron had negligible momentum, each gamma ray will have an energy of 0. 511 MeV. See also Electron-positron annihilation. Electron-positron annihilation occurs when an Electron and a Positron (the electron's anti-particle) collide

Electrons are a key element in electromagnetism, a theory that is accurate for macroscopic systems, and for classical modelling of microscopic systems. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of

Notes

See also

• One-electron universe
• Elementary charge
• Electron bubble

External links

• The NIST’s latest CODATA value for electron mass
• The Discovery of the Electron from the American Institute of Physics History Center
• Particle Data Group
• Stoney, G. The one-electron universe hypothesis commonly associated with Richard Feynman when he mentioned it in his Nobel lecture postulates that there exists only a single Electron The elementary charge, usually denoted e, is the Electric charge carried by a single Proton, or equivalently the negative of the electric charge carried An electron bubble is the empty space created around a free Electron in a cryogenic gas or liquid such as Neon or Helium. Johnstone, "Of the 'Electron,' or Atom of Electricity". Philosophical Magazine. Series 5, Volume 38, p. 418-420 October 1894.
• Eric Weisstein's World of Physics: Electron
• Researchers Catch Motion of a Single Electron on Video

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