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Element table question

  1. Nov 17, 2016 #1
    Well firstly let me say that I am no expert but it seems like the number of protons that determine the different elements is like a puzzle made by the universe? I mean they are all in sequence... am I missing something?
  2. jcsd
  3. Nov 17, 2016 #2


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    In a way, yes. Elements differ by the number of protons and neutrons. More as building bocks than as puzzle pieces since Mendeleev discovered the pattern.

    Why do you think you are misssing something ?
  4. Nov 17, 2016 #3


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    The number of protons determines the number of electrons. As there are rules how to arrange those electrons, some elements will have their last few electrons arranged in a similar fashion, with a certain periodicity. As these last few electrons, known as valence electrons, determine the chemistry of an element, there is some recurrence in the chemical properties, which is therefore related to the number of protons. This is the essence of the periodic table of the elements.
  5. Nov 17, 2016 #4
    Why are you puzzled that elements can be ordered as a recognisable sequence?, that there is a pattern?
    Would it not be more puzzling if the various elements had seemingly random properties bearing no relationship at all to other elements?
  6. Nov 21, 2016 #5
    Yes mostly that there is a pattern.

    And your statement is also interesting.

    Like I said I don't have much knowledge in chemistry or science and might be missing something but it seems peculiar that for it to be considered an hydrogen atom there HAS to be 1 proton and not 2 or that would make it a helium atom right?
  7. Nov 21, 2016 #6
    Yes, the number of protons, ( which is equal to the number of electrons) determine which element it is.
    Neutrons which can be present in different quantities determine which isotope of that element.
    Isotopes don't change the chemical properties of an atom, but some isotopes are involved with nuclear reactions.
    If you had a block of lead, it would likely contain many different lead isotopes, but chemically they all react the same way.

    The chemical reactions which can occur for a particular element are a result not of the number of protons in the nucleus,
    but of interaction between electrons, (which is the same number as protons).
    The electrons outside of the nucleus are organised into different shells (energy levels) and it is from this that the pattern seen in the periodic table emerges.
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