The five successive ionization enthalpies of an element are 800, 2427, 3658, 35024 and 32824 kJ mol. The number of valence electrons in the element is:

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Strategy:
 Successive ionization enthalpies reflect the subshell structure. A massive increase (jump) in energy indicates the removal of an electron from a stable, inner noble gas core. Electrons removed before this jump are the valence electrons.

Step 1: Analyze the IE values (kJ/mol)
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- 
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-  (Huge jump!)
-

Step 2: Conclusion
The jump occurs between the  and  ionization steps. This means the first 3 electrons are removed from the valence shell, and the  comes from a much more stable inne

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