Electrons Definition and 998 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. G

    Do electrons need specific energies to excite electrons

    Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?
  2. Z

    Electrons viewed in real time for the first time ever

    From the article: This is one of the first direct applications of attosecond pulses, but according to Berkeley researcher Stephen Leone, this is just the tip of the iceberg for what the technology can do. http://io9.com/5605687/electrons-viewed-in-real-time-for-the-first-time-ever Comment...
  3. D

    Are electrons constantly orbiting around the nucleus in an atom?

    Homework Statement Hi,I am currently studying A-level physics in the UK.:smile: I have been taught that electrons in an atom are orbiting around the nucleus. I would like to ask a question: Consider 2 situations: (1): A man is pushing a box forwards along a horizontal road. Work done...
  4. S

    Magnetism; the path of electrons

    The path of electrons emerging grom an accelerator must be bent by 90° by a 'bending magnet' so as not to strike a barrier in their path a distance d from their exit hole in the accelerator. Show that the field B in de bending magnet, which we assume is uniform and can extend over an area d*d...
  5. T

    Can Adding an Electron Change the Properties of a Hydrogen Atom?

    If you stuck 1 electron into the inner shell of a hydrogen atom, would the properties change? Thanks all, Joe.
  6. T

    Why Can Electrons in the Conduction Band Move Around so Easily

    As my title states, I want to understand why electrons in the conduction band can move around so easily in the material. Is it due to the presence of many closely spaced (blurred out) energy levels which make it easy for the electrons to move around? Or are the electrons undergoing some kind...
  7. V

    Proof of maximum no. of electrons in a shell

    how do you prove that the maximum no. of electrons in the nth shell of an atom is twice of n squared (2n^2)
  8. K

    Photons and electrons and electricity.

    A) I want to understand electricity in terms of quantum theory. as I understand photons are the carriers of EM energy so how do photons trasfer energy from electric company or battery through a wire. and the connection to electron movement (do electrons from one atom bum into another...
  9. jaumzaum

    Why electrons can have only 2 spin orientations?

    I'm studying electron spin/magnetic field and I was taught electrons can have only 2 spin orientations, as seen in the Stern and Gerlach experiment. But this orientations are given in relation to what? Do all electrons in the universe have the only 2 same orientations, or only the electron in...
  10. D

    Excitation of electrons in atoms

    I'm curious, when an electron is bombarded by another electron or photon does the electron even jump at all if the incoming particle does not have the minimum energy to make it jump to the second orbital. That is do the electrons have some sort of knowledge before the collision occurs and know...
  11. K

    Double slit experiment with electrons

    I often read that electrons that pass through two small openings in a wall will land on a back screen and make a pattern as if the electron were a wave. But if we look at the electrons the distribution on the screen is as if the electrons are particles. What does it mean to "look at the...
  12. M

    Counting Electrons & Protons in an Atom

    Hi all if we can't see an atom, how do we know how many electrons and protons by number it have ? please be as detailed as possible
  13. E

    How do electrons move in a circuit

    Apparently, this would be an easy question but I really have no clue. Consider a battery connected by a simple wire from positive terminal to the negative terminal. How do electrons flow? From -ve to +ve terminal? Right? NOW, how does it move so? In most texts, they say due to the potential...
  14. D

    How Do You Calculate Electron Tunneling Probability Through a Barrier?

    Homework Statement Electrons with energies of 0.201 eV are incident on a barrier 2.386 eV high and 0.383 nm wide. Find the probability for these electrons to penetrate the barrier. Homework Equations Note: h = h-bar k=Sqrt[2*m (V - E)]/h T = (1 + (V^2 (Sinh[k*L]^2))/(4*R (V -...
  15. Saitama

    How Do Electrons Focus When Emitted from a Cylinder?

    Homework Statement (see attachment 1) Homework Equations The Attempt at a Solution Here's what I've thought. See attachment 2. I think that the emitted electrons will follow trajectories which would intersect at a common point. The differently coloured trajectories shows...
  16. J

    Corralling Electrons: Wave-Particle Duality & Probability Waves

    I apologize if I am missing a major point, but I thought it was worth a try. If electrons are governed by wave-particle duality, do the waves permeate all of space? Does this mean that electrons we force into a particle, come from the same wave or do they have individual waves? And if so, how...
  17. M

    Is there a way to attract electrons to something?

    At the moment, I'm interested in power inhibition. One of my goals is to find something that knocks out power that DOESN'T damage equipment, like an EMP. I had an idea to find a way to attract electrons to an object, such as a magnet. Does anyone know of anything?
  18. H

    Trying to understand the oscillation of electrons in the magnetic fiel

    Working on understanding the physics of how an electron oscillates along the Earth's magnetic field. I understand that an electron will spiral around the magnetic field line, that's easy to tell from the Lorentz force. What I don't understand is what causes the oscillation. My best guess is...
  19. CivilSigma

    How many electrons would transfer 1 J of energy to a screen?

    My answer to a) is 1.14 * 10^-19 J, which is correct. My answer to b) is 1.14 * 10^19, which is not correct. The correct answer is 8.8 * 10^18. How did they get that? because if 1 electron has 1.14 * 10^-19 J then won't we need 1.14 * 10^19 electrons for 1 J ?
  20. M

    Chemistry Molecular orbital theory: assigning electrons

    Hello, Is it true that according to molecular orbital theory valence electrons in molecules are not assigned to individual atoms? Does this mean that even lone pairs are not assigned to inidividual atoms in a molecule , but rather assigned to a specified area across the molecule? Thanks!
  21. D

    Fermi Level of Electrons and Holes in Equilibrium and Non-Equilibrium

    Hi all, Why do the fermi level for electrons and holes coincide in equilibrium condition and why they separate as quasi fermi levels in non equilibrium situation?
  22. D

    Antineutrons, protons, electrons

    Is it theoretically possible to have: a) a helium atom with 2 protons, 2 electrons, and 2 antineutrons b) a helium atom with 2 negatrons, 2 positrons, and 2 neutrons c) a helium atom with 2 protons, 2 positrons and 2 neutrons etc...
  23. D

    Electrons in uniform magnetic field.

    Hello. So I was wondering that when you shoot an electron through an uniform magnetic field, obviously Lorenz force starts to skew the path to that corkscrew shape that we all know. But then there is an acceleration towards the center of the circle, and if the the velocity of the electron...
  24. Q

    How do you obtain electrons and know their average velocity?

    How do you obtain electrons and know their average velocity?? Hello guys! I am currently trying to experiment with charge accelerators. I soon tripped inside a really big hole. I soon realized that I didn't know how to measure the amount of charge(in coulombs) a charged conductor has. So...
  25. C

    Relaxation/Polarization with Semiconductor Electrons

    Please help me understand the following (general) statement, referring to electrons in a full valence band of an n-type semiconductor: "An electron filling up the last empty state in the valence band will in doing so prevent the other valence electrons from reducing their energy through...
  26. N

    Can Air Resistance Slow Down Subatomic Particles?

    Ok so if an electron is launched at a high speed such as 7 million m/s and it travels through air it would encounter resistance that would slow it down even though it is a subatomic particle. I am guessing that you would not be able to apply standard air resistance equations to figure out the...
  27. M

    How many strings make up protons, neutrons, and electrons?

    So I understand that: Protons= 2 up quarks and a down quark... and Neutrons= an up quark and 2 down quarks... and Electrons are not made of quarks (so small!) So my questions are: 1.) According the Heisenberg Uncertainty Principle, we don't know how many strings (according to string...
  28. T

    Electrons velocity and Potential energy

    hello all... i have a question: In an electric circuit the velocity of electrons are very small than how they will pass through all the elements of a circuit and gain or/and loss potential energy? for example let's take a basic circuit : An EMF and a resistor. How the electron in a resistor will...
  29. I

    Will free electrons experience its own electric/magnetic field?

    Hi, everyone :) Recently I've read a paper and found in that paper that the authors derived the wavefunction of moving free electrons from its own electric and magnetic field. It was quite a shock to me. So, for free electrons without external electric and magnetic field, why additional...
  30. T

    Do I Genghis Khans' electrons?

    I am wondering if there is an exchange of electrons in the flow of electricity. If I shove a fork in an outlet (i'm not going to do this) will electrons enter my body? Am I "absorbing new electrons" ? If so, where did they come from. I know how power generation works, but did those electrons...
  31. heycoa

    Solid State Physics | electrons | thermal conduction

    Homework Statement Explain why electrons carry a net energy but not a net current in the case of thermal conduction. Homework Equations n/a The Attempt at a Solution n/a Please help me understand this!
  32. J

    Number of electrons when something is charged

    When something is charged, is the number of excess electrons a large or small number when compared to the total number of atoms?
  33. S

    Equilibrium Distribution of Electrons and Holes

    Hello. I was studying the Semiconductor and I am confused with this diagram. I have attached the diagram. Please tell me briefly what does this diagram say. So that I could ask further. I have confusion with this diagram. I don't want to be specific so that you describe the whole diagram...
  34. Z

    How do electrons move? [Please read]

    Bear in mind, I may be very misinformed, I'm going from something I found on this forum a while back. Are you sitting comfortably? Well I'll begin. If the electron is indeed a point particle (zero volume) then how can it move without teleportation (of sorts) because say an electron has...
  35. A

    Hand contact with capacitor negative (excess of electrons) terminal only.

    Thank you for any help you are able to provide. I myself think that the electrons will flow to the human body and further drain the battery.
  36. M

    How Many Electrons Are Removed from a Charged Copper Ball?

    Homework Statement A 50.0 g ball of copper has a net charge of 2.00µC. What fraction of the copper’s electrons has been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)Homework Equations 1.00 C× (1proton)/(1.60×10^−19C)=6.25×10^18 protons C = coloumb, the SI...
  37. GreenAce92

    Can you strip away electrons completely from atoms?

    This is an arbitrary question Is it possible that regardless of whatever atom is present, a process is used to remove all electrons in the atoms that comprise a specific substance? For example if I had say what I will arbitrarily call "An electron boiler" and I just dump in any house...
  38. Q

    Can Electrons Conduct Heat? Exploring the Heat Capacity of Electrons

    Can an electron conduct heat? I know electrons are partially the reason why metals conduct heat, but can an electron itself conduct heat? In other words, does an electron have a heat capacity?
  39. C

    Free electrons in solid sphere of copper

    Homework Statement Use approximations to find the number of free electrons in a 4mm diameter solid sphere of copper. What fraction of its electrons have to be removed to leave a sphere with a charge of +50μC? Note that density of 29_Cu is 8.96 g/cm^3 and molar mass 63.54g/mol Hint: Atomic...
  40. J

    Is polar attraction stronger than the repulsion of electrons?

    So if any subtance has theoretically 0 degrees kelvin, it will be a solid, correct? So does that mean that temperature is the main factor that determines state of matter? What i mean to ask is, why would non polar molecules want to be close together like in a solid, when really, the electrons in...
  41. B

    How do you find the number of electrons given a mass fo the object?

    Homework Statement (a) Calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 13.0 g. Silver has 47 electrons per atom, and its molar mass is 107.87 g/mole. Homework Equations N/A The Attempt at a Solution I thought to try using the...
  42. G

    Electrons in a magnetic/electric field

    How could you tell whether moving electrons in a certain region of space are being deflected by an electric field or by a magnetic field (or both)? The answer from the textbook is: If the moving electrons are changing speed as they are being deflected, then an electric field is present...
  43. J

    What physical experiment would tell you how many electrons an atom has

    How did scientists/chemists experimentally determine how many electrons an atom has? Hydrogen, carbon, oxygen, etc... I'm wandering what physical experiment would tell you how many electrons an atom has?
  44. N

    Estimate the number of electrons flowing in a semiconductor pn junction

    Homework Statement The drift current in a p-n junction is 20μA . Estimate the number of electrons crossing a cross section per second in the depletion region. Homework Equations Drift current is the current that occurs due to formation of holes and electrons in the depleted region from...
  45. I

    How many electrons can the outermost shell hold? 32 or 8?

    In this physics textbook, in the part where it is introducing atoms and in particular, electron shells. it says: "the first and inner most shell has a capacity for 2 electrons, the outermost shell has a capacity for 32 electrons" I thought the outermost shell always had a maximum capacity...
  46. K

    Hadronic Electrons (Wolfram article, 1975)

    I've come across Stephen Wolfram's (creator of Mathematica) original paper in the 70s when he authored it when he was still a teenager, I think (which is pretty genius). Anyway it's about electrons that seemed to have "a neutral vector gluon cloud" and interact with gluons and the strong...
  47. Spinnor

    QED; electrons and photons, different fields, modes of a common field?

    In the Standard Model of particle physics are we to think of the electron(positron) field and the photon field as separate fields? Is it possible to think of the electron(positron) field and the photon field as just different "modes of vibration" of some more basic field? Can this line of...
  48. D

    What is the title of the webpage?Do Electrons Really Orbit the Nucleus?

    Hi. I have a little question. In some of my books you can read that the author keeps saying that an electron is orbiting around the nucleus in it's orbital, and if I'm not mistaken, some equations, or explanations, actually comes from assuming that electrons are orbiting the nucleus in a...
  49. S

    Electrons in electromagnetic induction

    Hello, when a coil rotates in a magnetic field an AC is produced at the ends of the coil but do that electrons come from the coil wire ? If yes, shouldn't the coil run out of electrons after some time ? thank you
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