What is Electrons: Definition and 999 Discussions

The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions. Since an electron has charge, it has a surrounding electric field, and if that electron is moving relative to an observer, said observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode ray tube experiment. Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.

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  1. Leo Liu

    B Why does our Universe have more electrons than positrons?

    In the known universe, the number of electrons seems to be greater than that of positrons since electrons are within every atom around us. However, when a gamma ray approaches a nucleus, a pair consisting of an electron and a positron, can be created from pure energy. If all matters are created...
  2. tanaygupta2000

    How Do Energy Levels Work for Electrons in a 1D Box?

    For the given problem, I know that the quantized energy for the particles in a 1D box is given by - E(n) = n^2 h^2/ (8mL^2) Here m = mass of electron L = Length of the box = a Now, since there are 8 electrons, but only 2 can occupy one energy level, so I used n^2 = (1)^2 + (2)^2 = 1 + 4 = 5...
  3. jaumzaum

    I Are the electrons in the conduction band completely free?

    I'm having trouble to understand why it's said that electrons in the conductor band are free while electrons in the valence band are not. I know by the Schrodinger equations that the trajectory of an electron inside a specific band and with a specific energy level is a probability. From what I...
  4. A

    B Can entangled electrons in helium be observed and measured in practice?

    If you measure the location of an electron in helium, does it impact the expectation value for the location of the other? Also, can this experiment be conducted in practice? Thanks.
  5. Adesh

    How can electrons flow all the way through the circuit?

    Electric currents and the things within are generally explained through the help of intuitive water current examples, where potential difference is explained through the pressure difference and electric current is explained as the flow of water. But I like to think in terms of some driving force...
  6. V

    Ultra Relativistic Free Electrons Gas

    I don't know how to approach this problem.
  7. JD_PM

    I Understanding the (polarized) cross section for Compton Scattering by electrons

    I have specific questions, but let's first give context. Initially we have an electron with momentum ##p=(E, \vec p)## and spin state ##u_r (\vec p)## and a photon with momentum ##k=(\omega, \vec k)## and polarization state ##\epsilon_s (\vec k)##. Finally we have ##p'=(E', \vec p')##, ##u_r'...
  8. S

    Do photons, phonons and electrons have mass?

    These articles have energy but do they have mass?
  9. troglodyte

    Do moving electrons also create an E-field?

    Hello guys, i get a little bit confused about the fact ,that static electrons produces E-Fields and after they moves one speaks only about the magnetic field .But what happens with the E-field in a moving ensemble of electrons?I mean,the E-field should also exists .It doesn't...
  10. A

    Energy gaps for quasi-free electrons in a 2D lattice

    Hi! Situation: quasi-free electron in a 2D lattice, considering atomic potential V(r) = exp{-|r|/b} (r is the distance from the atom) I'm trying to compute the first five energy gaps at point (10), firstly I don't understand the meaning of calculated 5 energy gaps at one point and usually we...
  11. r-swald

    Find the drift speed of of the electrons

    I've found I to be .167 using the potential and resistance. I also found the volume by multiplying the cross-sectional area by the length (?) and then dividing the # of conducting electrons into that to find packing density (n). To find drift speed, I would also need the area of the block as...
  12. I

    First ionization energy of group 1 and group 2 elements

    The first ionization energy decreases between group 5 and group 6 due to the repulsion between the electrons in the p orbital. Although I understand that the effective nuclear charge increases between group 1 and group 2 elements, why isn't this the case between group 1 and group 2 elements...
  13. G

    I White dwarf Ultra-relativistic electrons

    Hi! I have read a calculation about a white dwarf star assuming the electrons are both ultra-relativistic and degenerate. My questions is - how come the ultra-relativistic assumption doesn't contradict the "degeneracy" assumption. Degenerate means the electrons are filling out all the lowest...
  14. H

    I Right chiral vs left chiral electrons in the standard model

    Sometimes I hear particle physicists refer to left/right chiral electrons as different particles that are 'mixed' by the mass term. Maybe I misunderstood entirely, but if there is even a handwavy sense in which this is the case, clarifications would be appreciated. In high energy collisions...
  15. W

    Electrons @ battery negative terminal

    Does the negative terminal of a battery have a negative charge due to having a surplus of electrons? If so, then why do the surplus electrons from the negative terminal of the battery not discharge to the human body or Earth (which have a neutral charge) when touched?...thereby causing the...
  16. J

    Accelerating electrons and positrons

    I've been looking int Large Electron-Positron collider at CERN (an experiment which ended in the year 2000), groups of electron and positrons were accelerated along a circular tunnel so that they collided. Electromagnets were used to keep the particles moving in a circle. could someone tell me...
  17. patric44

    Derivation of the velocity of bloch electrons

    Hi guys I saw that equation of the velocity of electrons In a periodic potential $$ v = (1/h) grad E(k) $$ in my textbook we use in our solid state physics course without any proof or any thing and when I searched for it I found that its derived in Ashcroft book appendix E : Is there is any...
  18. A

    I Fermi-Liquid - amount of electrons available for the interaction

    I have attached the pages in Kittel's book (pages 417-420) regarding my question. My question is simply based off of the second to last photo, where e_f = 5*10^4 K and e_1 = 1K. e_2<e_f and |e_2|<e_1. So how can (e_1/e_f)^2 be less than 1? The energy of the free flowing electron is assumed to...
  19. J

    B Exploring the Delayed Eraser Phenomenon: Electron Edition

    Are there good references for delayed eraser experiments with electrons rather than photons?
  20. Saptarshi Sarkar

    Ground state energy of 5 electrons in infinite well

    As the temperature given was 0K, I calculated the ground state energy of the system. I considered 2 electrons to be in the n=1 state, 2 in the n=2 state and 1 in the n=3 state by Pauli's exclusion principle. By this configuration, I got the total energy of the system in the ground state to be...
  21. T

    In electrostatics, what is meant by positive charges?

    I am needing clarification for a concept. I understand that electrons carry a negative charge and that protons carry a positive charge. I also understand that a plastic rod picks up electrons when I rub it with a piece of wool. From the conservation of charge, the piece of wool must have a...
  22. Spinnor

    I Bohm guiding field, electrons in a semiconductor "box"

    Consider the light sensor in a modern camera. Light can give energy to electrons and populate the numerous "boxes" of our light sensor with extra electrons. Those boxes will temporally store the electrons till they are counted. I would like to understand this process with my "Bohmian" glasses...
  23. jisbon

    Fraction of valence electrons free for conduction

    For the first part, since this is a intrisinc semiconductor, n=p= intrisinc carrier concentration. Hence free electrons and hole = ##(1.5*10^{10})## per cubic centimeter. As for part 2, here are my steps. But I'm not sure if it's correct. I first find the number of atoms of one cubic...
  24. E

    Is thinking about "possession" of electrons a bad habit for dealing with formal charges?

    This isn't a specific question, but more a case of trying to mitigate any potential confusion which might arise in the future. When drawing out curly arrows for mechanisms, and the like, I'm used to thinking about which electrons "belong" to certain atoms (in a book-keeping sense) in order to...
  25. M

    What effect would accelerated electrons have in the air?

    I've been reading about semiconductor laser-driven particle accelerators over the years, and think they would make an interesting future-tech privacy screen...possibly. My design is along the lines illustrated by the diagram, but I'm wondering what actual effect accelerated electrons would have...
  26. I

    I About the repulsive force between two electrons

    hi, I have read that the process of repulsion between two similar charges, such as two electrons, is mediated by the exchange of a photon. This photon somehow merges with the nearby electron and somehow directs the electron to move in the opposite direction. Is this correct? I don't quite...
  27. HibyPrime

    B Gravitational wave emission from electrons

    Ok, so I've been on a kick trying to really understand why QM and GR are incompatible. I think I get that GR can't be realistically converted into a quantum field because it creates some infinite series that you can't use the normal tricks you would for other QM fields. Hard block, ok got it...
  28. F

    I QED & In-Ground Electrons: Why No Photon Emission?

    In ground state electron does not emit photon.Can we use QED to explain why in ground state electron does not emit any photons?
  29. J

    I Why don't Cooper electrons accelerate infinitely?

    Hello, I am trying to learn Quantum mechanics and have some questions I cannot answer. cooper pairs, composite boson particles (spin number = 0 or 1) from two coupled electrons. The movement of cooper pairs is forming a superconducting current. Superconducting current does not have a...
  30. PainterGuy

    B Electrons in a nonmoving conductor and non-varying magnetic field

    Hi, My understanding of quantum physics is very basic. I have read that each electron has its own magnetic field; in other words, each electron acts like a mini bar magnet. I was reading about Lenz's law and an unrelated point started confusing me. I was reading this text about Lenz's law...
  31. hnnhcmmngs

    Calculating Collision Frequency of Electrons in Copper Cube

    Homework Statement: Verify the claim of Section 7.2 that the electrons of a metal collide with the surface at a rate of about 10^30 per second per square centimeter. Do this by estimating the collision frequency of electrons in a 1.00-cm cube of copper metal with one face of the cube surface...
  32. D

    I QED question: Photons absorbed and emitted by electrons

    According to QED photons can be absorbed or emitted by electrons, and this process results in em forces via virtual photons. What determines the emitted photon frequency, and are they fully absorbed by electrons assuming photons are discrete and must be in quantized packets? How fast are...
  33. Michael Price

    A Measurements and electroweak gauge invariance/transformations

    Most gauge transformations in the standard model are easy to see are measurement invariant. Coordinate transformations, SU(3) quark colours, U(1) phase rotations for charged particles all result in no measurable changes. But how does this work for SU(2) rotations in electroweak theory, where...
  34. T

    Calculating the number of electrons given the force of repulsion

    Homework Statement: Two small spheres spaced 20.0 cm apart have equal charge. How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 3.33×10^−21N? Homework Equations: Charge of an electron e=-1.6X10^-19 C F=kq/(r^2) For this I set...
  35. I

    I Averge orbital distance of electrons

    Summary: Is there anyway to calculate average distance of electrons? I know that we use wave function for orbital to show the probability of finding but my question is there any way to calculate distance between orbitals or energy states?
  36. I

    B Do electrons accelerate when transitioning from one energy state to another?

    Do electrons have motion or they just accelerate when they get enough energy?
  37. mfb

    I New proton radius measurement with electrons favors "muon value"

    Publication News article It looks increasingly like something is wrong with the older electron-based results. The story of "with electrons you measure one thing, with muons another" doesn't work any more. Is that a good thing (there might be some conclusion what the radius is in the next years)...
  38. dRic2

    I Bloch functions and momentum of electrons in a lattice

    Hi, I'm a bit confused about Bloch functions. This is what, I think, I understood: can someone please tell me what's wrong? From Bloch's theorem we know that the wave-function of an electron inside a periodical lattice can be written as ##ψ_k(r)=u_k(r)e^{ik⋅r}##. We hope that far from a lattice...
  39. H

    I Spooky action at a distance by electrons?

    Electrons are indistinguishable, but we may pretend that they are distinguishable if their wave functions do not overlap in space. For example, an electron "a" in Chicago and an electron "b" in Seattle would produce a zero integral in [5.20], and so their indistinguishablilty would not produce...
  40. GuillemVS

    I Excited electrons' behaviour, how do they work?

    Mainly I want to know the following thing: electrons when excited they tend to want to go back to ground state, right? One way is by photons, but how does that work? Accelerating charges creates EM waves, but in this case there was no acceleration, right? Or is the term accelerating only a way...
  41. W

    I How electrons absorb or emit photons

    Hi, I am aware that the reason why objects have color is an old subject. However I come across two claims which sound like they are in contrast to each other. On one hand I read that the photons with specific frequency in incoming light are absorbed (i.e. have enough energy to move an electron...
  42. O

    I Can I detect electrons using X-ray film?

    I'm conducting a research about making a electron gun. I first tried to detect electron using nuclear emulsion plate. But I couldn't purchase one near my town. So, instead, I'm thinking about using a x-ray film to detect electron. But I'm not sure it'll work. SO, IS IT POSSIBLE TO DETECT...
  43. L

    I Is the Measurement Apparatus made up partly of electrons? Perhaps not.

    This is related to the thread "Is quantum theory a microscopy theory?" discussed mostly by Ph.Ds. I make this new thread so as not to disturb the experts discussions or even hijack or close it prematurely. In message #27 of...
  44. Anjum S Khan

    Can positive charge move between charged bodies like electrons do?

    Suppose , there is a body B1(-vely charged) and body B2(+vely charged). When both are on contact, electrons move from B1 to B2 as B2 is having electron deficit. But is reverse also possible that protons move from B2 to B1 as B1 is having proton deficit.
  45. Manasan3010

    I Exploring the Physics of Photoelectric Cells: Electrons, Energy & Color

    In this article, writer says that when atom is hit by photon it gets excited and expelled out of atom and this can be used to form images. My questions are: Why didn't the electrons get to a higher energy level, instead of getting knocked out? How do we find the color(frequency of wave) using...
  46. J

    Moving Electrons in a Uniform Magnetic Field

    a) We can solve for acceleration by looking at FNETy FNETy = FE (G is negligible) FNETy = m * a The mass (m) of an electron is 9.1093836 x 10-31 kg. The elementary charge (q) of an electron is -1.60217662 x 10-19 C a = ε * q / m a = (4.0 x 102 N/C * 1.6022 x 10-19 C) / 9.1094 x...
  47. I

    Basic questions about plasma and electrons in space

    If i get this right: In space when electrons leave its atoms, do they attach to something else? Or is the electrons bouncing freely in space when they get detached? Is this because of dark energy? And if so, where do they go? Do they move between atoms or are the free to go anywhere? And where...
  48. J

    B Shrødinger equation & electrons jumping between atoms

    (I have very little training in Quantum mechanics) Can the Shrødinger equation show the probability distribution of the electron when it jumps from one atom to another, like in a circuit f ex. Thanks!
  49. DaveC426913

    B Length contraction of a pair of electrons

    I've managed to stump myself in attempting to answer a member on another forum. He is attempting to demonstrate length contraction using two electrons a known distance apart and moving at a known velocity.My thought experiment is based on his proposal; that's why I've chosen the components I...
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