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Why we called the Helium particle as alpha particle?

  1. Dec 6, 2015 #1
    why we the alpha particle is taken as helium and beta as electron ?
    and what about gamma particle ? what is that?
    My 2nd question is that during alpha decay and beta decay there is decrease of 2 units in atomic number and one unit increase respectively ?
    what happen in gamma decay ?
     
  2. jcsd
  3. Dec 6, 2015 #2
    Gamma radiation is electromagnetic radiation.
    It's the most energetic kind of EM, much more energetic than X rays, visible light, radio, and other forms of electromagnetism.
    The naming alpha/beta/gamma for the 3 basic kinds of radioactivity are simply the first 3 letter of the Greek alphabet, like a, b, c.
    There is no particular reason why 'a' is helium nucleii, 'b' is electrons and 'c' is EM, but I'm guessing it may be to do with the ordering of the time of their discovery.
     
    Last edited: Dec 6, 2015
  4. Dec 6, 2015 #3

    Nugatory

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    Staff: Mentor

    It's an accident of history. We named the first kind of radiation discovered "alpha", the second "beta", and the third "gamma" after the first three letters in the Greek alphabet. Only later did we figure out the that the particles in alpha radiation were helium nuclei, the particles in beta radiation were electrons, and the particles in gamma radiation were....
    Highly energetic photons.

    What do you think and why? Consider the electric charge of the various particles involved.
     
  5. Dec 6, 2015 #4
    so is there photons also present in these atoms ? which emit during radioactivity in the form of gamma rays ?
     
  6. Dec 6, 2015 #5
    sorry. i didn't get your question. I think what will happen with gamma decay ? as beta and alpha decay can change the atomic numbers and as a result a new element is formed.
     
  7. Dec 6, 2015 #6

    Nugatory

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    Staff: Mentor

    Yes, emission of an alpha or beta particle changes the atomic number. You asked whether emitting a gamma particle would also change the atomic number and I told you try figuring it out for yourself first, and gave you a big hint that you should be thinking about the electrical charges of the various particles involved... and I'll even give you another big hint: What is the atomic number of a nucleus and how is it related to electrical charges?

    (The Physics Forums rules discourage giving people answers until they've made an effort to figure things out for themselves first.)
     
  8. Dec 6, 2015 #7
    Atomic number is the number of protons. A positive charge. Gamma rays have no charge. So no effect on atomic number ??? Am i right ? is there any other effect of this emission of photons ?
     
  9. Dec 6, 2015 #8
    When I was studying this for my GCSE physics course we only looked at the alpha and beta decay equations, however, my physics teacher did give me some room to wiggle here, so I studied Beta decay quite thoroughly, and here we go.

    Beta decay

    To find the answer to what you seek, you must answer me these questions three:
    1. What is atomic mass vs atomic number? Define the two terms and find the difference.
    2. What is the actual difference between protons and neutrons? Why is this? (You may find yourself looking into quarks here.)
    3. Beta decay has an increase in atomic number, and an emission of an electron, but no increase in simple atomic mass. How can you tie what you learned in the previous question to these facts?
    Useful tips!
    • Electrons are not mass-less.
    • Protons and neutrons do not have the same mass.
    • When I said there was no change in atomic mass, I lied, there is a slight decrease.
    • Electrons are surprisingly insignificant to understanding what beta decay is, unless you are actually talking about the emission.

    Hopefully, I've helped you discover the answer on your own here.
     
  10. Dec 6, 2015 #9

    Nugatory

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    Staff: Mentor

    Yes you are.

    Only a reduction in the one thing that the gamma particle does carry away, namely energy. Gamma radiation happens when a nucleus is "excited", meaning that it has an excess of energy. Usually this happens because some previous decay released more energy than was carried away by the alpha or beta particles from that earlier decay - eventually the excess energy escapes as gamma particles.
     
  11. Dec 6, 2015 #10
    Thank you... Understood
     
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