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Ionization Potential

  1. Nov 28, 2003 #1
    Which of the following atoms has the lowest ionization potential?
    a. 2 4 He
    b. 7 14 N
    c. 8 16 O
    d. 18 40 Ar
    e. 55 133 Cs

    The answer is e. Can someone explain the general concepts and reasoning behind this? Thanks,
  2. jcsd
  3. Nov 28, 2003 #2
    In my humble opinion this is dirty chemistry.... The theory behind this goes back to electron shells in elementary chemistry for example the s1, s2, p1, s3, p2, d1 and so on. It is a matter of knowing which shells fill how man 'slots' there are in each level and intuiting the qualitative ionization potential. The s shells have 2 slots, the p shells have 6, the d shells have 10,and the f shells have 14... You can figure out where the electrons are with simple subtraction knowing the patterns of filling. Remember that the s orbitals of the n+1 level typically fill before the d orbitals of level n. It's easy to note the pattern of Ionization potential when shown a chart of them, check one out it'll be a tremendous help.

    A) He; Helium is going to have a relatively high ionization potential because it has only two electrons which completely fill the lowest (and closest to positive nucleus) energy shell. {2 electrons in S1} 24.5 eV

    B) N; Nitrogen fills up the lowest energy shell the s2 orbital and half of the p1 orbital (half an orbital is stabilier than half +1 of an orbital in the lower atomic numbers).{2 in S1, 2 in S2, and 3 in p1} 14.5eV

    C) O; Oxygen is Nitrogen plus one and as mentioned above half a full orbital is stabiler than half plus one at this atomic level.{2 in S1, 2 in S2, 4 in p1} 13.6eV

    D) Ar; Argon has filled S1, S2, P1, S3, and P1. Since it has filled them it has a high ionization potential of 15.8 eV.

    E) Cs; Cesium is by far the best choice of these elements for the lowest ionization energy. It has S1->5 filled, p1->3 filled, and d1 and 2 filled. There is a lonesome electron in the 6th S orbital that is far out from the nucleus which is very easily removed due to it's distance and the fact that it is alone in an orbital. {2 in S1->5, 6 in p1->3, 10 in d1,2 and only 1 in S6.} IP of 3.9eV

    I hope this helped, I'm not the best at exlpaining stupid chemistry!

    Bored CSMPhysicist
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