Electron Definition and 999 Threads

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. B

    Can electron be considered a Source of gravitational field?

    Hello PF members, Source of the gravitational field in the Einstein field equations is energy–momentum tensor and the curvature of space-time is directly related to the energy and momentum of whatever matter and radiation are present. Suppose a electron at rest . 1- Can this electron be...
  2. C

    Equation for the energy of an electron

    Hello, I would like to thank all of the contributors on this site. You have helped me in more ways than I can count. I am struggling with the following concept and was wondering if anyone could clarify this. As the electron gets further away from the nucleus, its energy increases. This makes...
  3. B

    How Do Electrons Form a Bond in Covalent Bonding Despite Their Mutual Repulsion?

    There's a rule bout unlike charges attract and like charges repel one another. How is it that in chemical bonding like in covalent bonding electrons form a bond or there is attraction from one unto the other. Isn't that ironic?
  4. ptownbro

    Electron Energy Level Fall at a Given Wave Length

    1. Homework Statement An electron in the H atom falls from n=(?) to n=3. The wave length of the emitted photon is 1100 nm. From what level did the photon fall? Homework Equations Used the following to get the Energy. w = c / v E = h * v E = h * (c/w) w = lambda (couldn’t figure out how to...
  5. ptownbro

    Energy release and levels during electron transition

    Homework Statement Been looking but can't seem to find any comprehensive help on this. In the Hydrogen atom, what energy is associated with these electron energy transitions: a) N = infinity to N=2? b) N = infinity to N=3? c) N = 4 to N=2? d) N = 5 to N=6? I don't have any relevant formulas...
  6. Phynos

    De Broglie Wavelength for 1Mev electron

    Homework Statement Calculate the de Broglie Wavelength of a 1 MeV electron. Express your answer in femptometers. Homework Equations ## λ = h/p ## ## p = (2mT + T^2/c^2)^{1/2} ## The Attempt at a Solution basically just plugged everything in. ## λ = \frac{h}{(2mT + T^2/c^2)^{1/2}} ## ## λ...
  7. ZapperZ

    See an Electron Lately? - Comments

    ZapperZ submitted a new PF Insights post See an Electron Lately? Continue reading the Original PF Insights Post.
  8. J

    What is electron? Is it a perfect point? What does it mean?

    Electron is usually imagined as a simple point charge, but in fact it is a very complex entity: https://dl.dropboxusercontent.com/u/12405967/electron.png - being electric charge itself means singular(-like?) configuration of electric field - E behaves like 1/r^2, - it is also magnetic dipole...
  9. C

    Hydrogen Emission Spectrum, Electrons, and Quantized Energy

    I understand that the result of the hydrogen emission spectrum experiment was that only certain wavelengths of light were emitted and that led to the conclusion that electrons emit light when they relax and that they absorb light when they get excited. How does that prove that the energy for...
  10. T

    How Do You Integrate the Electron Heat Capacity Integral by Hand?

    1. The answer to this problem is easy when plugged into mathematica it's (pi^2)/3. I am trying to integrate it by hand however and can't figure out how to start it. I also can't find any other attempts of it online (our professor says we can just look it up if we can find it). [(x^2*E^x)/(E^x...
  11. M

    Finding the electron drift speed

    Homework Statement A piece of n-type germanium is 2.0mm wide and 0.25 mm thick. At a certain temperature, the number of conduction electrons per cubic metre is 6 x 1020 m-3. What is the average drift speed of the electrons when a current of 1.5 mA flows? (e=1.6 x 10-19 Homework Equations...
  12. A

    Velocity of Electrons: Orbital Motion & Velocity Explained

    What is the relation between the orbital motion and velocity of electron? Do the electrons close to the nucleus have high velocities or those who are in higher orbits?
  13. A

    Can an atom exist without any electron?

    Can an atom exist without any electron? If yes, then how?
  14. N

    Electron Capture by alpha particle -- Frequency of photon?

    Homework Statement Electron with KE = 50eV is captured by Alpha particle, ie. HE++. Calculate the frequency of the emitted photon. Homework Equations KE = m/2 v^2; E=hf, En = Z^2*-13.6eV/n^2 The Attempt at a Solution Energy before = Energy after 50eV = 4*-13.6eV/1 + hf f = 1200nm
  15. K

    What is the Quantization Scheme in Frohlich's Electron-Phonon Interaction Paper?

    I am reading Frohlic's paper on electron-phonon interaction. Frohlic.http://rspa.royalsocietypublishing.org/content/royprsa/215/1122/291.full.pdf Here author has introduced the quantization for complex B field in this paper and claimed to have arrived at the diagonalized form of the...
  16. N

    (Check solution) Frequency of light after electron capture?

    Homework Statement An alpha particle: He++ captures an electron of a given kinetic energy. To conserve energy, it emits light, hf. How would one calculate the frequency? Homework Equations E=hf En = (Z^2 *-13.6eV)/(n^2) The Attempt at a Solution Calculate En. Then KE = Photon + En. Solve for...
  17. A

    Is an electron a delocalized excitation before measurement?

    When we observe an electron it is always a localized excitation in the electron field. But when it's not being observed, does the excitation begin to spread through space and become a delocalized excitation?
  18. Leef

    Free floating electron quantum spin axis locked to space?

    This is my attempt at understanding any real world physical effects from quantum spin. I will start with the short version first. A ... When we have a free floating electron in space is the physical orientation of the quantum spin axis locked into a fixed 3D orientation and from there can only...
  19. M

    Electron-Proton Atoms in a Unique Universe: Could They Exist?

    1. Imagine a universe where electrons and protons have positive and negative electric charges, respectively. Could an atom consisting of one electron and one proton exist in this universe?2. None.3. My first thought was that such an universe already exists (ours) since an atom with a negatively...
  20. M

    Electron-Proton Pair: Exploring the Possibility in an Alternative Universe

    Imagine a universe where electrons and protons have positive and negative electric charges, respectively. Could an atom consisting of one electron and one proton exist in this universe?
  21. A

    The current of a single electron

    I guess my question has multiple parts. Any help in understanding the questions is appreciated. Assume a single electron in free space. The electron starts moving because of some force applied to it. The source of the force could be pretty much anything, let's say a uniform E-field in X...
  22. C

    Nichrome and Copper Circuit w/ Electron Mobility

    Homework Statement In the circuit shown, two thick copper wires connect a 1.5 V battery to a Nichrome wire. Each copper wire has radius R = 0.009m and is L = 0.17m long. Copper has 8.4 \times 10^{28} mobile electrons/m^3 and an electron mobility of 4.4 \times 10^{-3}(m/s)/(V/m). The Nichrome...
  23. J

    Exploring Electron Scattering in Crystalline Nickel Foil

    Homework Statement A beam of electrons with kinetic energy 50 eV is fired at a 100 nm thick crystalline nickel foil. (a) Calculate the speed of the electrons in the beam.(b) Based on your answer to part (a), state, with justification, whether classical (Newtonian) mechanics correctly...
  24. K

    Understanding Electron Chirality and Scalar Conservation

    (1) electron = left chiral . anti electron = right chiral. positron = left chiral. anti positron = right chiral. So scalar couples L and R chiral fermion fields. (2)electron = left chiral . anti electron = right chiral. positron = right chiral. anti positron = left chiral. So scalar...
  25. Tone L

    Calculating Electron Density: Ionospheric Research

    Homework Statement I am conducting some research and have come across a problem, it could very well be misunderstanding. I am trying to calculate electron density N.Homework Equations There was given a simple formula F = 9√N ... where F = critical frequency and N = electron density... But...
  26. I

    Electron Entanglement in Vacuum: Exploring Quantum Mechanics

    Hi, Can two free electrons in a vacuum become entangled as a result of a collision between the two? I have seen examples of electrons being entangled when bonded to atoms and in other circumstances, but not in this case. Can anybody shed some light on this topic? And, more...
  27. D

    Conservation of energy violation of galvanic cell electron

    When a galvanic reaction reclaims its (single) electron, magnetic energy (about 0.356 eV) within a superconductor will remain, w/o a means of replacing the galvanic electron. During the reaction, electrical current from the single electron would correspond to the number of times per second...
  28. yeshuamo

    Kinetic energy of electron: Quantization of angular momentum

    Homework Statement Show that the quantization of angular momentum implies that the kinetic energy of the electron is quantized as K=nhforb/2, where forb is the frequency of rotation. Assume circular orbit. Homework Equations Radial acceleration: arad = v2/r = (4π2r/T = 2*π*v/Tr = nħ KE =...
  29. A

    A electron cyclotron has a frequency of 2450 Hz and a magnet

    Homework Statement A electron cyclotron has a frequency of 2450 Hz and a magnetic field strength of 50T.? a) what's the speed of the electron? b) what was the voltage on the electron gun which projected the electron into the cyclotron? Homework Equations Givens: r=.4m B=50T f=2450Hz...
  30. T

    Why Does the Ni+ Ion Have an Electron Configuration of [Ar]3d9?

    Homework Statement Which is the electron configuration of the Ni+ ion? Homework Equations Ni : [Ar]4s23d8 The Attempt at a Solution Ni+: [Ar]4s13d8 Apparently this solution is wrong and should be Ni+: [Ar]3d9 but I do not know why. As far as I know 4s has less energy than 3d so, why does one...
  31. P

    Highest probability of finding an electron

    Hello. I have found an exercise that reads: "The wave function of a one-electron atom is: [1s orbital, atom: Li2+ What will be the most likely distance to locate the electron?" Solution of exercise is: My question is: Why the square of the probability density is dP/dV, and therefore the...
  32. O

    Calculating Electric Field from Electron Drift and Diffusion in Si Sample"

    Homework Statement A sample of Si, in which 0<=x<=(25*10^-4), electron concentration is n(x)=5*10^16 cm^-3) * exp(-x^3/2*10^-8), temperature is 300k and electron mobility is 1300 cm^2/V*s. The electron current through the Si has both drift and diffusion components and total electron current...
  33. ltl94

    Larmor Radius for an electron in the K Corona of the Sun

    1. Compute the Larmor radius for a typical electron in the K corona.2. , , m=9.11×10-31 kg, q=1.602×10-19 CThe Attempt at a Solution My problem is I don't know where to find the other two values that correspond specifically to the the K corona. Then it becomes a simple plug-and-chug problem...
  34. Telemachus

    Transmission Electron Microscopy

    I'm looking for a quick and well synthetized reference to the TEM technique. I'm writing a monography, we used TEM on a sample (just sended it to the lab, I dind't do the work). I don't have any reference, and I wanted to give a kind of introduction in the monography to TEM. I don't want a whole...
  35. N

    How the features of electron represented in it ?

    How the features of electron (or other elementary particle) like mass , electric charge ,magnetic moment and more represented in it ? Is each of the features should not be represented as a sub-particle in the electron ?
  36. N

    Which radiation emitted by circadian electron ?

    Which radiation emitted by an electron that moves in a circular motion ? And how radiation can be emitted by an elementary particle?
  37. L

    Effective Mass of Electron in Polyethylene

    Hello friends Can anyone tell me the effective mass of electron in polyethylene and how it depends on the crystalline nature of polymer.
  38. sa1988

    Electron velocity through earth's magnetic field

    Homework Statement Electron is traveling in line with the equator, perpendicular to Earth's magnetic field of 6E-5 Tesla. What velocity is required for the electron to stay in a straight line path, such that it's weight is exactly matched by the magnetic force against it. Homework Equations...
  39. F

    Electron microscope particle relativistic mass

    Homework Statement They were going to purchase an electron microscope, and wanted the electrons velocity to be as high as 25% of the speed of light after acceleration. There was a microscope at hand that had an accelerating voltage of 40 kV. a) How large is the electrons relativistic mass when...
  40. Gerry Rzeppa

    Electron Re-arrangement and Flow in Power Lines

    I've been doing some bedtime reading in Chabay & Sherwood's Matter & Interactions textbook (https://www.amazon.com/gp/product/0470503475/?tag=pfamazon01-20) and have come across some interesting tidbits. Here they are: I've always pictured electrons pushing each other through a wire, kind of...
  41. stackprogramer

    An electron in atom that rotate proton, has it radiation?

    Hi dears,i have a question about atom,in classic physics ,(Bohr theory) when a electron swing away a proton it have not radiates magnetic waves because if electron radiates magnetic wave it will drop on proton ,and atom will be Unstable! my question is ,in quantum mechanics that uses orbitals...
  42. O

    Electron potential/momentum problem

    Homework Statement To produce x-ray radiation, electrons are accelerated in vacuum and aimed so as to collide with a target. Assume that all of the electron kinetic energy is converted into the energy of the x-ray photon on collision and that the wavelength of the resulting radiation is 1.24...
  43. F

    Creating a positron and a electron with a photon

    Homework Statement Hi everybody. I have to demostrate that a photon, no matter it's energy, will never be able to create a positron and an electron on it's own. Homework Equations E=Sqrt(m^2+p^2) as long as c=1 Conservation of energy Ei=Ef; initial energy is equal to final energy...
  44. Z

    QM explanation of electron conduction in crystal

    Suppose that a static electric field E is applied on a conductive crystal. Then, how quantum mechanics describes the electron movements in the crystal? I have been trying to find an explanation, but have not found any. As I understand it, we could treat the E field as a time-dependent...
  45. TheExibo

    Why do noble gas electron configurations have large radii?

    In my lecture, we were told that a nitrogen with a negative 3 charge has the largest radius compared to most of the other atoms in the same period. How is that possible? It has more protons attracting the valence electrons closer to the center, but the prof said that because three electrons are...
  46. F

    Measuring spin of a free electron

    Hi everybody. I have been reading about the Stern Gerlach experiment lately and a doubt has came to my mind. Is there any way to know the spin of an electron without forcing it to interact with a magnetic field? Thanks for reading.
  47. N

    Electrons are not elementary particles?

    http://www.nature.com/news/not-quite-so-elementary-my-dear-electron-1.10471 Scientists have split an electron into 3 quasiparticles in the lab, why isn't this updated on the standard model?
  48. E

    Bohr model and relativistic electron mass

    From the semi-classical Bohr model of the hydrogen atom the velocity of the electron in a certain orbit can be determined. With these velocities the electron's relativistic masses can be determined. With E=mc2 the energy levels are in agreement with those from the Bohr model. I know Bohr's model...
  49. O

    Does Applying an Electrical Field to One Side of a Conductor Double the EMF?

    Assume a conductor in a rectangle shape for simplicity. Now, if I only choose one side of this rectangle, and apply external electrical field ∑ only to it, what EMF would I create on the conductor? I would simply say ∑, however then I had the following idea, and I started to doubt if I create...
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