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Mendeleev's table - complete?

  1. Dec 25, 2009 #1

    This might be a pretty stupid question to you guys, but it started to bug me.

    Are the elements that Mendeleev's table contains all the possible atoms that our universe contains or could there be more which we just dont know about?
    And if it is complete, why arent there any more possibilities? Is it because of the size of the nucleus?

    Thanks in advance,
  2. jcsd
  3. Dec 25, 2009 #2


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    Merry Christmas!

    Hi fawk3s! :smile:

    A new atom would have a new combination of numbers of protons and neutrons in the nucleus.

    Its place in the Mendeleev table is fixed only by the number of protons.

    Two atoms with the same number of protons but different numbers of (neutral) neutrons would have the same electron shell structure, and so would be chemically the same, which is why they would be called the same element, and be in the same position in the table.

    So the only place there can be gaps in the table is on the right-hand end, and indeed new elements are occasionally added there.

    See http://en.wikipedia.org/wiki/Island_of_stability" [Broken] and links from it.
    Last edited by a moderator: May 4, 2017
  4. Dec 25, 2009 #3


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    We pretty much know all the elements that are stable. The rest are radioactive.

    As far was we know, the laws of Nature apply in the visible universe as they do here.

    www.webelements.com displays the periodic table and has some information on the superheavy elements.
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