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How is electron formed? Why does it travel?

  1. Sep 14, 2007 #1
    I understand that electron is made up of leptons which are made up of energy. But what I don't understand is that how can leptons be just made up of energy, I mean its not like a balloon. Another thing is that Wikipedia claims that Leptons and Quarks are the only 2 fundamental particles...but then what is neutrino made up of? What about antineutrino? I understand that this universe is made up of energy but then why is it moving?(why are the electrons spinning and rotating?) Don't tell me b/c the entropy is increasing b/c then I'll ask what caused the big bang. If like Hawkins, you say it is a cycle, then are you telling me time never began?
  2. jcsd
  3. Sep 14, 2007 #2
    You are making a mess.
    1) An electron is not "made up of leptons"; it's a lepton itself.
    2) Neutrino IS a lepton (and so antineutrino too).
    3) Leptons and quarks are not the only fundamental particles, unless you substitute the word "particles" with the word "fermions".
    4) Electrons doesn't spin.
    However there are many people here who knows these things better than me.
  4. Sep 14, 2007 #3
    If they don't spin then why do they talk about half integer and integer spin? Besides, how are electrons created? Why do they rotate around the protons? Are the fermions and Bosons the only fundamental particles then(being leptons, quarks, gluons, photons, and w and z bosons.)?
    Last edited: Sep 14, 2007
  5. Sep 14, 2007 #4
    Are you looking for answers in terms of the symmetry properties, like U(1), SU(2), SU(3), etc? Maybe someone more equiped could give us a brief summary of how particles are supposed to be the result of symmetry properties.
  6. Sep 14, 2007 #5


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    I believe the entymology of the term is that you have to spin an electron 720 degrees before it returns to its original position: you get half of a full rotation in a 360 degree rotation.

    They don't. They don't revolve around protons either. An electron in an atom simply sits there, occupying its entire orbital.
  7. Sep 14, 2007 #6


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    I have never heard of this. I will defer to what I assume is your better knowledge on the subject, but my understandnig has been that, while electrons do not "orbit" the proton, they do not simply "occupy" the orbital either.

    It was my understanding that they do actually move, and that the orbital merely describes a probability of where they will likely be found when sought out.
  8. Sep 14, 2007 #7
    If thats the case then why don't they stick to the protons since they are attracted to it? Besides, thats what my chemistry teacher taught me. Also, how is it created? and how does it die?
  9. Sep 15, 2007 #8


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    What? The electrons? They're neither created nor destroyed. They're fundamental particles.
  10. Sep 15, 2007 #9
    What about others? Protons, neutron, gluons, nuetrinos, etc. Btw, when you said destroyed, you meant naturally right? B/c they can easily be destroyed if they meet their anti.
  11. Sep 15, 2007 #10
    proton's coulomb potential confined the electron cloud. But the electron cloud density in the nuclues center is zero.
  12. Sep 15, 2007 #11
    I think the picture of electron cloud spinning around the nuclues should be physical
  13. Sep 15, 2007 #12


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    No, in the ground state hydrogen atom, the electron's probability density (per unit volume) is actually maximum at the origin (the nucleus)!


    You may be thinking of the "radial probability distribution" (probability density per unit radius), which does go to zero at the origin. But this is a geometrical artifact. The radial probability distribution gives you the probability that the electron is located somewhere in a thin spherical shell of radius r and (small) thickness dr. The volume of that spherical shell decreases to zero as r decreases to zero, so the radial probability distribution does also.

    The electron doesn't "stick" to the proton because if it did, they would combine to form a neutron, emitting a neutrino in the process. But a neutron has a larger mass than a proton plus an electron, so this can't occur spontaneously; something would have to supply enough energy to create the increased mass.

    In some heavier atoms, an electron can "stick" to the nucleus, converting a proton to a neutron and emitting a neutrino, provided that the resulting nucleus has a smaller mass than the original one plus the electron. This process is called electron capture. It's one mode of radioactive decay.
    Last edited: Sep 15, 2007
  14. Sep 15, 2007 #13
    You ask these questions like the answer, "That's reasonable, but we simply don't know" is unacceptable. What caused the big bang? Whatever you want to pretend caused it. No on can say for sure right now.

    Did time have a start at some point? Maybe, maybe not. Is this really a problem? Not so much -- it's weird, but not really unreasonable.
  15. Sep 15, 2007 #14
    I am wondering about the more accepted theory. Ofcourse nothing is proven, but right now, scientific method is the most accepted way.

    Btw, you guys are getting way too advance here, I am lost. Now, in a more elementary manner, why don't the electrons stick w/ protons?
    Last edited: Sep 15, 2007
  16. Sep 15, 2007 #15


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    I'm not an expert on this subject (yet), but let me try to clear things up a bit.

    No, an electron is a lepton. Lepton is a name for a whole family of particles (muons, tau particles, neutrino's, etc)

    Just as anything in our universe.

    There is nothing to understand here, it's just something fundamental. Probably, when you say energy, you have in mind the stuff that moves objects around and heats your house. In fact, energy is a fundamental quantity, which - as far as I know - cannot be defined. We just divide energy that we see up in different forms (kinetic energy, chemical energy, mass, temperature, etc) though all of these are really the same thing.

    I don't see the connection between those statements. Why would the universe being made up of energy exclude it from moving? Do you mean: why is part of the energy that makes up the universe in a form that we call kinetic energy?

    Electrons are kept near atomic nuclei because of nuclear forces (mainly, Coulomb interaction). It's common to picture an electron as revolving around the nucleus in an orbit, just as a planet revolves around the sun. But in reality, we cannot pin-point the exact location on a given moment in time. We can just (by quantum mechanics) calculate the probability that we will find it in that-and-that area. Likewise, the name spin is confusing -- it refers to a property of (among others) electrons which has certain similarities to the classical spin of for example a ball or a top (in fact, it is similar to the orbital rotation, but it's an intrinsic property, like classical spin - hence the name I think). But the name is also a bit misleading, as the object does not really spin around an axis (in fact, we can look at an electron as a wave, rather than a solid "ball").

    So, in both cases, nothing really "spins", it's just an attempt to link some strange, quantum-mechanical properties to familiar concepts, which gives us some grasp on the ideas, but one cannot extend the analogy too far.

    You mean, if a proton is positive and an electron is negative, why don't they attract and collide? I think there is no answer without involving quantum mechanics again (sorry about all the QM, but on this scale, that's just the theory you need to accurately describe nature), but perhaps this link will give you some reading.
    Last edited: Sep 15, 2007
  17. Sep 15, 2007 #16
    "Do you mean: why is part of the energy that makes up the universe in a form that we call kinetic energy?"

    Yes! and thanks for the other answers you and other folks.

    One more thing, I understand that all protons and Neutrons are collected together by Strong Nuclear Force and you told me that Electron are attracted to Protons due to weak nucleus force(so charge is basically weak nucleus force). Then how is one atom attracted to other?(gravity? What is the source of it?) How is one molecule attracted to another?(what I mean is that whenever 2 compounds meet, why do they start chemical reactions instead of repulsing each other?(I took AP Chem but trying to keep up my grade was a greater priority for me then understanding it)
    Last edited: Sep 15, 2007
  18. Sep 15, 2007 #17
    Excepting in those few rare cases of pair productions and annihilations.
    Last edited: Sep 15, 2007
  19. Sep 15, 2007 #18
  20. Sep 15, 2007 #19
    Electrons are attracted to protons because of Coulomb force.
    This is more complicated to answer. First, interatomic forces are different from the intermolecular ones, and in this last case there are more kinds.

    a. Interatomic forces. Let's make a simple example: two hydrogen atoms (covalent bond, in this case). Even in this case the answer is not simple; simplyfing a lot, we can say one reason is the fact the electron of atom A is attracted to the proton of atom B too, and the same between electron of B and proton of A. All this however holds true in a specific range of distances, because in other ranges it's electronic repulsion (*) (simplifying again) to prevail on the first effect.

    b. Intermolecular forces. As I said there are many kinds. However we can say that the main cases involve, at the end, electrostatic or electrodynamics forces, so, no gravity (in the sense that gravity do act, but with enormously lower intensity, so that it's never considered in these cases).

    Some kinds of intermolecular bonds:

    1. Van Der Waals bond. It's present in many cases, even together with other kinds of bond. It's present, e.g., in molecules with no net dipole moment or in big molecules. It's the reason of molecular hydrogen condensed states, for example.
    2. Ionic bond. Is the case of common salt, NaCl. The crystal is made of Na+ and Cl- ions, which attracts one to another; a Na+ ion attracts more than one Cl- ions and the other way round, so you have an entire macroscopic structure, instead of single, detached molecules.
    3. Covalent bond. It's the same as the bond between two hydrogen atoms in molecular hydrogen, but in this case the bond is extended to all atoms. One example is sylica, another is diamond.
    4. Dipole-dipole interactions. Example: forces between HCl molecules. (HCl molecule has a separation of charges so a net dipole moment; two dipoles can attract one another).
    5. Ionic - dipole interactions. Example: Ions hydratation.
    6. Hydrogen bond. It's a kind of half-way between 4. and 5. Typical of water molecules e.g.
    7. Metallic bond. Semplyfing: it's kind of the case of H-H bond, but involving a huge number of electrons and nuclei all together

    In 2., 3. and 7. cases, molecules cannot be distinguished, so they actually cannot be called intermolecular bonds. I put them in that group just because they involve many atoms at the same time.

    (*) or nuclei repulsion.
    Last edited: Sep 16, 2007
  21. Sep 15, 2007 #20
    But shouldn't the atoms be repelled from each other due to electron repulsion?
    So at what level gravity force comes into effect?
    How is Coulomb's force created?(I understand they exist between charges but why?)
  22. Sep 15, 2007 #21


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    Atoms are usually, essentially electrically neutral. The + and - effectively cancel out (though not completely, or we'd have no molecules).

    Gravity is in effect at all scales, but it is many, many, many orders of magnitude smaller than the other forces. It can for all practical purposes be treated as zero, which is why it does not factor in at atomic levels.
  23. Sep 15, 2007 #22
    If you read well what I wrote, you would have understood that there is indeed electronic repulsion, but *also* attraction between electrons and nuclei. Which effect prevails depends on atomic distance.
    There isn't a net separation, since gravity acts always and its action increases with the mass of the body we are considering. To make gravity so strong to break atoms, however, earth's mass is still not enough; sun's mass it is. So this can give you a slight idea.
    As far as i know, in some theories that force is equivalent to curvature in an higher dimension, like gravity is equivalent to space-time curvature, according to GR (General Relativity); but I actually know nothing about it.
  24. Sep 15, 2007 #23
    But what is gravity? I mean I am sure it doesn't at photons level, so I am guessing it starts at atomic level...I know it is the fact that all atoms are attracted to each other...is it because of the neuclei?

    Someone inhere said earlier that electrons are never created nor destroyed....but how is that possible? If Universe, time, basically everything has a beginning, then how come they exist since forever? And if they have existed after that time, then how?
  25. Sep 15, 2007 #24
    Gravity can be seen as just an effect from the curvature in space-time. Or if you prefer you can look up gravitons, supposed massless particles that travel between all bodies conveying attraction.

    Light is affected by gravity and will bend towards massive objects.

    But gravity has no place in a discussion on atoms. It is so much weaker than the other forces at play that you would not notice if it disappeared.
  26. Sep 15, 2007 #25
    How can a massless object convey attraction? Since it is massless, how can it attract anything?
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