Ionization Energy differences

  • #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.
 

Answers and Replies

  • #2
274
0
Why is the second ionization energy of K so large? Think octet rule.
 
  • #3
261
2
A qualitative analysis should suffice, provided that you show enough knowledge about valence electrons and ionization energies.
 
  • #4
132
1
President Mercury said:
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.

looks like a lab question. The Calcium reacts faster than the Potassium because more energy is removed in a period of time...
 
Last edited:
  • #5
12
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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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