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Homework Help: Periodic trends

  1. May 23, 2015 #1
    1. The problem statement, all variables and given/known data

    Which of the following atoms has the largest first ionization energy?

    • Potassium,
    • Zinc,
    • Gallium,
    • or Krypton?

    2. Relevant equations
    No equation

    3. The attempt at a solution

    Krypton has the largest first ionization energy, but I was wondering how this question would be different if it were asking for the largest electronegativity or electron affinity?

    In that case, since Krypton is an ideal gas, I would think that Gallium would have the largest electronegativity and electron affinity. And if a question were asking for the largest atomic radius, the answer would be Potassium. So my question is just making sure that the only periodic trend that also pertains to ideal gases would be the ionization energy trend (increasing from left to right across the period table), and atomic radius (if a question were to ask about the largest atomic radius, it increases down a group and decreases from left to right across the periodic table). Do I have that right? Because since the ideal gases have the full octet, I would think they would not have high electronegativities. Thanks!
  2. jcsd
  3. May 24, 2015 #2


    User Avatar

    Staff: Mentor

    Not "ideal gas" - noble gas.

    In general - instead of asking, google for "atomic radius of xxx", or "electronegativity of xxx", collect the data and see if you are right, or not. Periodic trends are not invented, they are based on the experimental data. Paraphrasing words of Richard Feynman - it is nature that is always right.
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