What is Electron: 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. P

    Determine electron density with impurites

    Homework Statement Let’s introduce an imaginary atom which can replace the silicon atom and generate one mobile electron. What is electron density when all silicon atoms are replaced by this imaginary atom Homework EquationsThe Attempt at a Solution I have tried looking for a formula to...
  2. P

    Electron Density when Introducing Impurites

    How do you go about calculating electron densities, especially when impurities are involved?
  3. B

    Do photon apply a force to the electron ?

    Hello PF members, In Newtonian perspective, applying a force to a object like ball causes it starts to moving and getting more speed and more energy. Do photon apply a force to the electron when it interacts with the atom and electron absorbs it? It seems electron gets more energy and goes to...
  4. G

    Free electron laser weapon -- operating wavelength for the US navy's 1MW FEL?

    I know fel operate a wide range of wavelengths, but does anyone know the main operating wavelength for the US navy's 1MW fel?
  5. P

    Relativistic angular moment of electron in electric field

    Homework Statement Consider an electron with spin ##\vec{S}## and magnetic moment ##\vec{\mu}=-\frac{e}{m}\vec{S}##. It is moving with the velocity ##\vec{v}(t)## relative to the inertial frame of reference ##I## through the electric field ##\vec{E}##. Calculate the angular momentum the...
  6. A

    Angle of deflection of electron

    Homework Statement 2 parallel plates of length 4.0 cm are arranged horizontally in a vacuum. The upper plate is positively charged and the lower plate is negatively charged. An electron is projected horizontally with an initial velocity of 6.0 x 106 ms-1 and experiences a constant electric...
  7. I

    I Proton / electron mass ratio equation

    Hi all, I'm new to the forum so I hope this is the right place to pose this question. I've managed to find answers to nearly all of the questions I've had regarding certain aspects of physics on the forums, but haven't seen this addressed anywhere. According to Wikipedia (...
  8. P

    Quantum Tunneling of a conduction electron in Copper

    Homework Statement A conduction electron moves through a block of Cu until it reaches the surface. At the surface the electron feels a strong force exerted by the nonuniform charge distribution in that region. This force tends to attract the electron back into the metal which is what causes the...
  9. M

    How can electron in hydrogen ever get in the 2s state?

    I am trying to understand selection rules in atomic transitions. So, one of the selection rules says that only transitions where orbital quantum number is changed by 1 are possible. If that is the case how can hydrogen in ground state get to 2s state? Can we detect spectroscopic line that...
  10. Garlic

    Electron capture in fully ionised nuclei

    Hello everyone, What happens if an isotope that normally decays through EC has no electrons at all? For example how does 7Be4+ decay?
  11. Kerrigoth

    I Are the positive charges from a hole and a proton ?

    The book I'm reading is discussing the physics of semiconductors. I'm having a hard time understanding a passage in section introducing n-type semiconductors. (Phosphorus is used as the impurity) The book says: "At normal operating temperatures, this extra electron breaks its bond with the...
  12. Flinze

    Instantaneous Velocity of a electron with a provided formula

    Homework Statement The motion of an electron is given by x(t)=pt^3 +qt^2 +r, with p = -1.9 m/s^3 , q = +1.3 m/s^2 , and r = +9.0 m. What is the velocity at: a) t=0s b) t=1s c) t=2s d t=3s Homework Equations v=x/t The Attempt at a Solution I have tried plugging in the time to equal to t, in...
  13. S

    Uncovering the Strength of SEM's Electromagnetic Lenses

    Does anybody happen to know the strength of the electroMAGNETic lenses of a scanning electron microscope? I was thinking of using solenoid coils, which would be enough if I am willing to increase the focal distance, but the lenses on SEM's seem far larger.
  14. A

    Calculate the electron kinetic energy ejected from cathode?

    I would like to calculate the electron kinetic energy ejected from a cathode as a function of the electric field and pressure without known of the temperature and velocity.
  15. G

    How Does a High-Intensity Laser Interact with an Electron Cloud?

    A high intensity continuous wave laser passes through an electron cloud. Please discuss what would happen and in relative amounts. Thanks
  16. tom.mulloy

    Single electron ....two slits?

    Hi, I am a newby so please excuse my ignorance. With reference to the single electron double slit experiment, one thing has been bugging me. The videos that illustrate the particle or wave behaviour do not tell us how the single fired electrons are directed to either the left or right slit...
  17. Stephanus

    Electron shell, Oxidation number

    Dear PF Forum, I think I have asked too many question for one day. I'm trying to understand antioxidant and free radicals. But, first I'd like to understand oxidation number. The oxidation number for hydrogen is +1 or -1. I can understand that. Either Hydrogen must lost one electron or gains one...
  18. N

    Electron ejected in Photoelectric effect

    Since the binding energy of an electron in outer shell is smaller than the binding energy of the electron in inner shell, why the photon kick out the electron orbiting in inner shell? It is always easier to kick out the electron with less binding energy, is it not?
  19. N

    Secondary effect of Electron capture and Internal conversion

    During Internal conversion, the nucleus transfer some energy to an electron in K-shell cause the electron eject out of the atom. After which there left a hole in K-shell then either by releases auger electron or characteristic X-ray the atom de-excited itself. During Electron capture, a proton...
  20. Error404!

    Problem With Motion of Electron

    Are axis of rotation and revolution of an electron revolving a nucleus parallel? if axis of rotation and revolution of Earth can be not parallel to each other then why not for electron? We add or subtract (s) = 1/2 (value of spin quantum number) to orbital quantum number (l) to get total angular...
  21. G

    Electronegativity and electron affinity?

    Why is the electronegativity of fluorine higher than chlorine but not electron affinity? How is it possible that it has a stronger attraction towards a bonding pair of electrons than when a new electron is added to the atom?
  22. Jan Wo

    Getting electron density from probability density function

    Hello Lastly I was thinking a lot about electron density definition. It is not intuitive for me and I'm looking for any mathematical tool that could explain it to me more. My friend told me about idea to derivate it from propability density function using Dirac delta distribution. I'd like to...
  23. Stephanus

    Exploring the Confusing Units in Physics: Electron Volt & Volt

    Dear PF Forum, I'm interested in the future. How mankind will benefit from fusion power. But there are some terms that I don't understand. Electron Volt. https://en.wikipedia.org/wiki/Electronvolt Volt https://en.wikipedia.org/wiki/Volt Perhaps this yes/no question will confirm my confusion...
  24. F

    Do the Krebs cycle and electron transport chain require ATP?

    I cannot find a website that answers this question, and all diagrams I see do not show that ATP is used. Does this mean that these processes are intrinsically spontaneous? I can see how the electron transport chain is spontaneous, as the oxidation of oxygen to water is favorable (E 1/2=0.7V).
  25. J

    Basis for electron spin in a quantum field

    I get the notion that an elementary particle derives from a localized perturbation of that particles quantum field. What I don't get is how that perturbation can lead to two alternative quantum states for that particle - for example, an electron with two spin states (spin up and spin down). Are...
  26. Jan Wo

    Interpreting Electron Density Definition

    Hi I'd like to ask you about interpretation of electron density definition. According to the "Handbook of Molecular Physics and Quantum Chemistry" it goes like: ##\rho (\textbf{r})=N \sum_{\sigma_1}^{\sigma_N} \idotsint_{\mathbb{R^3}} |\psi_V (\textbf{r}_1, \sigma_1;\dots...
  27. Quotidian

    Are Electrons Really Indistinguishable in the One Electron Universe?

    I have heard that Feynman and Wheeler briefly discussed the idea of the 'one electron universe'. According to Wikipedia it came up as follows: It wasn't really a serious idea, more a 'thought experiment'. But what interests me is the fact that electrons are literally indistinguishable. Not...
  28. NatFex

    Identify this piece of equipment?

    We were digging through some of the apparatus today and amongst a few dual beam tubes we found this, pictured below It's very similar looking to a dual beam tube shape-wise but as you can see the internal structure is quite different. What is this? After looking at it for a while we suspect...
  29. D

    Electron and wavelength problem

    Homework Statement Electron on n=6 level emits wavelength of 410.2nm. What energy level does it move too? Homework Equations 1/L = R ( 1/N^2 - 1/n^2) where N is initial and n final R=1.096779*10^7 m The Attempt at a Solution 1/410.2 = 10967790 (1/36 - 1/n^2) 1/4498975152 = (1/36 - 1/n^2)...
  30. A

    What holds the electron intact?

    I was reading the book "Electricity and Magnetism" 3rd edition (Purcell, Morin) and under section 1.3 the book says (I quote): "What holds the electron together is as mysterious as what fixes the precise value of its charge. Something more than electrical forces must be involved, for the...
  31. B

    Internal Energy of an Electron

    Homework Statement What is the internal energy of an electron moving at 0.750c0 in the Earth reference frame? Homework EquationsThe Attempt at a Solution E = mc^2 E = (9.11 * 10^-31)(.750)(3*10^8) However, this appears incorrect. What have I done wrong or what am i missing?
  32. P

    Finding Escape Speed for an Electron that's Initially at Res

    Homework Statement What is the escape speed for an electron initially at rest on the surface of a sphere with a radius of 1.0 cm and a uniformly distributed charge of ##1.6\times 10^{-15}##? That is, what initial speed must the electron have in order to reach an infinite distance from the...
  33. Q

    Minimum work to transport electron?

    Homework Statement A charge Q = -820 nC is uniformly distributed on a ring of 2.4 m radius. A point charge q = +530 nC is fixed at the center of the ring. Points A and B are located on the axis of the ring, as shown in the figure. What is the minimum work that an external force must do to...
  34. Einstein's Cat

    Distance between positron and electron

    Is there a way in determining the distance between an electron and a positron as they anhilliate? If this figure has been determined already, what is it? Thank you very much for your help!
  35. Ryan Reed

    Do Electrons need Energy to Excite the EM field?

    Electrons have both mass and electromagnetic charge, so why is it that an electron's rest energy is equal to its mass energy with E=mc^2? Shouldn't it have some energy left over to excite the electromagnetic field? The mass energy excites the Higgs field, so why is there no energy for the EM field?
  36. Ryan Reed

    Do Electrons Excite the EMF or do the Virtual Photons?

    Do electrons excite the EM field or do they just create virtual photons that do? If you could only see EMF excitations, would you see the electrons or virtual photons coming from the electrons?
  37. J

    CPT transformation analogue of free electron laser?

    While 2nd law of thermodynamics emphasizes past->future time direction, CPT theorem says that at least microscopic physics has some symmetry between past and future. For example the Feynman-Stueckelberg interpretation suggests to see anti-particles as traveling back in time. So thermodynamics is...
  38. M

    Photoelectron to electron hole pair doubts

    Hi, I have a couple of questions on photoelectrons. When a photoelectron of about 3-eV (varies) interacts within 0.2-um depletion region of silicon, what happens? I know, it will generate an electron-hole pair with an efficiency of 1 for 3.6-eV photoelectron. But what happens if the...
  39. J

    Anderson localization and electron flow/diffusion?

    Imagine a semiconductor lattice - a regular lattice (e.g. of Si or Ga) with a small fractions of a different atoms (like Mn). The natural question is: how electrons flow through it? It can be measured experimentally: put a potential and use scanning tunneling microscope to map electron flow from...
  40. S

    Electron Spin Problem: Exploring the Stern-Gerlach Experiment

    Hello, I've been reading the Stern-Gerlach experiment, and where the concept of electron spin is introduced, am facing a problem, i.e., if you consider electron a charged rotating sphere, then the electromagnetic energy and size of the electron becomes huge! So how do you deal with this? Thanks...
  41. N

    I Double Slit Experiment: Questions Raised & Explanations Needed

    I was watching a video about the double slit experiment because I found it interesting, However, watching this vid raised more questions than it did answer. I would like to know why did the outcomes of the experiment only change when we observed it... wasn't the electron interacting with...
  42. 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...
  43. 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...
  44. 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?
  45. 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...
  46. 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...
  47. 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...
  48. ZapperZ

    See an Electron Lately? - Comments

    ZapperZ submitted a new PF Insights post See an Electron Lately? Continue reading the Original PF Insights Post.
  49. 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...
  50. 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...
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