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Homework Help: Ionization Energy differences

  1. Oct 4, 2006 #1
    Question: The first and second ionization energies of K are 419 kJ/mol and 3052 kJ/mol, and those of Ca are 590 kJ/mol and 1145 kJ/mol, respectively. Compare their values and comment on the differeneces.

    I'm thinking of two different ways of how to do this even though I think both are wrong. I was wondering if I had to take the energy of K and Ca and subtract them? OR do I just look at them and speak about how "different" they are from each other?

    I don't know if I'm thinking about this question in a logical way or not? So feed back would be much appreciated. Thanks.
  2. jcsd
  3. Oct 4, 2006 #2
    Why is the second ionization energy of K so large? Think octet rule.
  4. Oct 4, 2006 #3
    A qualitative analysis should suffice, provided that you show enough knowledge about valence electrons and ionization energies.
  5. Oct 5, 2006 #4
    looks like a lab question. The Calcium reacts faster than the Potassium because more energy is removed in a period of time...
    Last edited: Oct 5, 2006
  6. Oct 23, 2006 #5
    Well, first of all, the first ionization enrgy of Ca is greater than that of K because Calcium's nucleus is more effective due to an increased effective nuclear charge. Next, the second ionization energy of Calcium is less than that of K because it is removing an electron from a more excited orbital than the orbital the second electron from K is being removed from. The second ionization energy of K is also about 6x greater than its first ionization energy because it is pulling an electron from a less excited orbital with less shielding and is closer to the nucleus, wheras the second electron being removed from calcium is from the same orbital as before.
    I hope that I answered your question!
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